ICWS 2007

Message from the General Chairs

Frank Leymann,Ming-Chien Shan — 8/09/2007 02:11

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.118

Message from the Program Chairs

Ken Birman,Liang-Jie Zhang,Jia Zhang — 8/09/2007 02:15

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.120

Message from the Application Services and Industry Track Chairs

Wu Chou,Paul Hofmann — 8/09/2007 02:19

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.117

IEEE Computer Society Technical Committee on Services Computing

7/26/2007 02:11

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.99

Organizing Committee

7/26/2007 02:12

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.137

Program Committee

7/26/2007 02:13

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.145

Technical Steering Committee

8/09/2007 02:26

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.172

External Reviewers

7/26/2007 02:24

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.90

Services Research at IBM

Robert Morris — 9/05/2007 23:10

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.164

Web Services: Meeting the Software Challenge of Future Hardware and Global Business Trends

Ike Nassi — 9/05/2007 23:12

In today's global economy, companies are challenged to become more efficient and agile in the face of increased transparency in their supply chains and rising compliance requirements. In addition, IT hardware continues to increase in price and performance resulting in more information storage, processing capabilities and network throughput. In fact, by the year 2010 we could see over 100 cores per server with multiple terabytes of memory.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.194

Message from the IEEE ICWS/SCC/SERVICES 2007 Plenary Panel Program Co-Chairs

Ling Liu,Frank Ferrante — 7/26/2007 02:47

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.119

Services Computing in Daily Work: Service Engineering vs. Software Engineering

Hemant Jain,Calton Pu,Sridhar Iyengar,Brian Blake,Carl K. Chang — 9/05/2007 23:15

Today, more and more software are augmented with service-oriented packaging. At the same time, more and more business and government services are provided and offered in the form of software. However, there are debates on whether and how much service engineering has in common with software engineering.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.163

Services Computing in Action: Services Architectures

Ephraim Feig,Liang-Jie (LJ) Zhang,Ali Arsanjani,Zhiwei Xu — 9/05/2007 23:17

This panel is devoted to the topic of Services Architectures, which play a significant role in the effective operations and delivery of services businesses today.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.162

SOA Solution Reference Architecture

Liang-Jie Zhang — 9/29/2007 23:35

In this tutorial, we present the results of abstracting a reference architecture for SOA based on multiple projects during the past 6 years. As an example SOA Solution Reference Architecture, the SOA Solution Stack (S3) defines the layers, architectural building blocks, design decisions, patterns, options and architectural decisions and the separation of concerns needed to model, architect, assemble, deploy and manage an end-to-end solution in the context of a service-oriented approach. The SOA Solution Stack (a.k.a. Service-oriented Solution Stack) provides a blue print for an enterprise or application architecture scope. The SOA Solution Stack is based on establishing the building blocks of SOA: services, components and flows that collectively support business processes and goals. The meta-data underlying each layer and relationship between layers can further facilitate SOA in bridging the gap between business and IT from solution modeling to solution realization.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.166

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State of the Art in Modeling and Deployment of Electronic Contracts

Kamalakar Karlapalem,Pisipati Radha Krishna — 9/05/2007 23:22

Modeling and deployment of e-contracts is a challenging task because of the involvement of both technological and business aspects. There are several frameworks and systems available in the literature. Some works mainly deal with the automatic handling of paper contracts and others provide monitoring and enactment of contracts. Because contracts evolve, it is useful to have a system that models and enacts the evolution of e-contracts.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.169

Build Your Mashup with Web Services

Ning Yan — 9/05/2007 23:40

Mashup is presenting new kind of application in web 2.0 world. Mashup is not simply about the AJAX technologies, rather, it is typically related to reuse the data and other services from other web side and web applications. There are many ways to build up the mashup.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.61

Web Services Security and Privacy

Patrick C. K. Hung,Casey K. Fung — 9/29/2007 23:46

Web services are becoming widely deployed to implement the automation of business processes such as supply chain management, inventory tracking, and healthcare management, just to name a few. A Web service is a new breed of web application that supports interoperable application-to-application interaction over a network based on a set of XML standards.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.192

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Semantic SOA in Action: A Practical Demonstration

Parachuri Deepti,Bijoy Majumdar,Ujval Mysore — 9/29/2007 23:53

This tutorial is intended for researchers and industry practitioners who are interested in modeling ontologies to support knowledge engineering and management, database modeling, business process modeling and enterprise information integration with a focus on practical demonstration. The tutorial gives a deeper insight for designing of ontologies and conceptual modeling.

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DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.158

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An Access Control System for Web Service Compositions

Mudhakar Srivatsa,Arun Iyengar,Thomas Mikalsen,Isabelle Rouvellou,Jian Yin — 9/28/2007 22:35

Service composition has emerged as a fundamental technique for developing Web applications. Multiple services, often from different organizations or trust domains, may be dynamically composed to satisfy a user's request. Access control in the presence of service compositions is a challenging security problem. In this paper, we present an access control model and techniques for specifying and enforcing access control rules on Web service compositions. A key advantage of our approach is that past histories of service invocations can be used to make access control decisions. Our approach allows role hierarchies and separation of duty constraints. Access controls rules may be parameterized by one or more arguments. We have implemented our access control model via a declarative policy specification language which uses pure-past linear temporal logic (PPLTL).We describe an implementation of our approach using a supply chain management (SCM) application. Our experiments show that our approach can enforce expressive and flexible access control policies while incurring reasonable performance overhead on the application.

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Information Flow Control with Decentralized Service Compositions

Ustun Yildiz,Claude Godart — 9/28/2007 21:07

Decentralized execution settings are primordial for most processes where process participants are required to establish P2P interactions. This is particularly true for processes that subject the composition of services advertising different information flow policies. To provide a systematic approach to manage the information flow between composed services, we present a methodology that derives cooperating distributed processes of a centralized specification with respect to their information flow policies. Our contribution shows how service compositions, that cannot be realized with centralized orchestrations or inconsistent choreographies, can be realized with equivalent decentralized executions in an inexpensive and in a reasonable manner.

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Efficient and Secure Search of Enterprise File Systems

Aameek Singh,Mudhakar Srivatsa,Ling Liu — 9/28/2007 22:42

With fast paced growth of digital data, keyword based search has become a critical enterprise application. Research has shown that nearly 85% of enterprise data lies in flat filesystems [10] that allow multiple users with different access privileges. Any search tool for such systems needs to be efficient and yet cognizant of access control semantics imposed by the underlying filesystem. Current enterprise search techniques use two disjoint search and accesscontrol components by creating a single system-wide index and filtering search results for access control. This approach is ineffective as index and query statistics subtly leak private information. The other approach of using separate indices for each user is undesirable as it not only increases disk consumption due to shared files, but also increases overheads of updating indices whenever a file changes.

We propose a distributed approach that couples search and access-control into a unified framework and provides secure multiuser search. Our scheme (logically) divides data into independent access-privileges based chunks, called access-control barrels (ACB). ACBs not only manage security but also improve overall efficiency as they can be indexed and searched in parallel by distributing them to multiple enterprise machines. We describe the architecture of ACBs based search and propose an optimization that ensures the scalability of our approach. We validate our design with a detailed evaluation using industry benchmarks and datasets. Our initial experiments show secure search with 38% improved indexing efficiency and low overheads for ACB processing.

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Uniform Dynamic Deployment of Web and Grid Services

Pu Liu,Michael J. Lewis — 9/28/2007 22:45

The Web Services Resource Framework (WSRF) has redefined grid computing standards, making Web services more suitable for grid applications by adding persistent state management. However, it is still difficult to build, deploy, and evolve such services, since different Web and grid services containers require that the services they host be written in specific languages, to target particular internal interfaces for state management. Therefore, services must be built and deployed differently for each hosting environment. This paper describes uniform dynamic service code deployment on three Web services containers (namely, Tomcat, ASP.NET and a gSOAP based C++ container), and two grid services containers (namely, GT4 and WSRF.NET). Containers receive the code in an XML-based standard intermediate form, and then generate container-specific native code in different languages, without exposing these details to applications and grid services programmers. The dynamically deployed code can access state managed by the hosting container, can utilize functionalities exposed by statically deployed services, and can communicate with other dynamically deployed modules, running either in the same container or in different containers. A performance study shows that the newly deployed mobile code can run nearly as efficiently as it would if it had been deployed statically, through container-specific mechanisms.

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An Evaluation of Multiversion Concurrency Control forWeb Service Directories

Walter Binder,Samuel Spycher,Ion Constantinescu,Boi Faltings — 9/28/2007 22:42

Web service directories are shared resources that have to accommodate a high number of concurrent read requests, whereas updates are relatively infrequent. To allow for the automatic composition of complex web services based on those contained in a directory, read requests may involve a series of queries which require a consistent view of the data. We have developed an efficient web service directory that is based on the Multiversion Generalised Search Tree (MVGiST), an integration of a multidimensional index structure with multiversion concurrency control. The MVGiST is able to index web services according to their input and output parameters, supports a high level of concurrent read requests, and guarantees consistency across multiple subsequent read queries. In this paper we evaluate the performance and scalability of the MVGiST and compare it with a traditional, locking-based concurrency control mechanism.

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Capacity Management and Demand Prediction for Next Generation Data Centers

Daniel Gmach,Jerry Rolia,Ludmila Cherkasova,Alfons Kemper — 9/28/2007 22:47

Advances in server, network, and storage virtualization are enabling the creation of resource pools of servers that permit multiple application workloads to share each server in the pool. This paper proposes and evaluates aspects of a capacity management process for automating the efficient use of such pools when hosting large numbers of services. We use a trace based approach to capacity management that relies on i) a definition for required capacity, ii) the characterization of workload demand patterns, iii) the generation of synthetic workloads that predict future demands based on the patterns, and iv) a workload placement recommendation service. A case study with 6 months of data representing the resource usage of 139 workloads in an enterprise data center demonstrates the effectiveness of the proposed capacity management process. Our results show that when consolidating to 8 processor systems, we predicted future per-server required capacity to within one processor 95% of the time. The approach enabled a 35% reduction in processor usage as compared to today’s current best practice for workload placement.

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Modeling and Diagnosing OrchestratedWeb Service Processes

Yuhong Yan,Philippe Dague — 9/28/2007 22:42

Web service orchestration languages describe executable business processes composed of Web services. A business process can fail for many reasons, such as faulty Web services or mismatching messages. It is important to find out which Web services are responsible for a failed business process because we could penalize these Web services and exclude them from the business process in the future. In this paper, we propose a model-based approach to diagnose orchestrated Web service process. We convert the Web service orchestration language, BPEL4WS, into synchronized automata, so that we have a formal description of the topology and variable dependency of the business process. After an exception is thrown, the diagnoser can calculate the business process execution trajectory based on the formal model and the observed evolution of the business process. The faulty Web services are deduced from the variable dependency on the execution trajectory. We demonstrate our diagnosis technique with an example.

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User Tasks and Access Control overWeb Services

Jacques Thomas,Federica Paci,Elisa Bertino,Patrick Eugster — 9/28/2007 22:48

Web services are a successful technology for enterprise information management, where they are used to expose legacy applications on the corporate intranet or in businessto- business scenarios. The technologies used to expose applications as web services have matured, stabilized, and are defined as W3C standards. Now, the technology used to build applications based on web services, a process known as orchestration, is also maturing around the Web Services Business Process Execution Language (WS-BPEL). WS-BPEL falls short on one feature though: as it is focused on orchestration of fully automatic web-services, WSBPEL does not provide means for specifying human interactions, even less their access-control requirements. Human interactions are nonetheless needed for flexible business processes. This lacking feature of WS-BPEL has been highlighted in a white paper issued jointly by IBM and SAP, which "describes scenarios where users are involved in business processes, and defines appropriate extensions to WS-BPEL to address these." These extensions, called BPEL4People, are well explained, but their implementation isn’t. In this paper, we propose a language for specifying these extensions, as well as an architecture to support them. The salient advantage of our architecture is that it allows for the reuse of existing BPEL engines. In addition, our language allows for specifying these extensions within the main BPEL script, hence preserving a global view of the process. We illustrate our extensions by revisiting the classic loan approval BPEL example.

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Workload-aware Business Process Simulation with Statistical Service Analysis and Timed Petri Net

Seiichi Koizumi,Kazuya Koyama — 9/28/2007 22:50

To adapt systems in response to new business requirements with SLA, business process performance simulation will play a key role. This paper proposes a performance model for business process that comprises control flow structure (such as loop) and parallel message execution under shared resources. A network queuing model is inappropriate to model dynamic workload in the business process execution since messages are processed in parallel consuming shared resources. In our previous work, we have proposed a statistical service model to estimate execution time based on workload overlap analysis.

In this paper, we extend this approach to model a business process with control flow. We integrate a Timed Petri Net model and our statistical models for services and process engines. We have implemented a prototype system for supply chain scenario. Experiments with this prototype show high accuracy of performance simulation.

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ModelingWeb Services using Semantic Graph Transformations to aid Automatic Composition

Zhen Liu,Anand Ranganathan,Anton Riabov — 9/28/2007 22:50

In this paper, we propose a novel way of modeling web services using semantic graph transformations. Each operation supported by a web service is associated with a semantic annotation that describes the input and output messages using RDF graph patterns. The terms used in these patterns are defined in OWL ontologies that describe the application domain. A key difference between our model and existing semantic web service models like OWL-S is that it describes the inputs and outputs in terms of instance-based graph patterns, rather than in terms of concepts. This allows associating a rich set of constraints on the input and output data in terms of relations between instances. We also propose a composition model for web service operations, that describes the conditions for composing services into workflows. The composition model includes the notion of semantic propagation, i.e. the semantic description of the output message of an operation depends on the semantics of the input message. We have developed a planner that uses this model to compose services, automatically. The planner uses DLP reasoning to aid plan search. We present performance results for the planner.

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Improved Matchmaking Algorithm for Semantic Web Services Based on Bipartite Graph Matching

Umesh Bellur,Roshan Kulkarni — 9/28/2007 22:51

The ability to dynamically discover and invoke a Web Service is a critical aspect of Service Oriented Architectures. An important component of the discovery process is the matchmaking algorithm itself. In order to overcome the limitations of a syntax-based search, matchmaking algorithms based on semantic techniques have been proposed. Most of them are based on an algorithm originally proposed by M. Paolucci, et al. [19].

In this paper, we analyze this original algorithm and identify some correctness issues with it. We illustrate how these issues are an outcome of the greedy approach adopted by the algorithm. We propose a more exhaustive matchmaking algorithm, based on the concept of matching bipartite graphs, to overcome the problems faced with the original algorithm. We analyze the complexity of both the algorithms and present performance results based on our implementation of both these algorithms. We show that the complexity of our algorithm is equivalent to that of the original algorithm in spite of the improvements we have made to address the correctness issues.

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Applying Abduction in Semantic Web Service Composition

Freddy Lecue,Alexandre Delteil,Alain Leger — 9/28/2007 22:52

The semantic Web promises to bring automation to the areas of Web service selection, discovery, composition, invocation. In this paper we introduce a means of facilitating automation of Web service composition by exploiting semantic matchmaking between Web service parameters (i.e., outputs and inputs) to enable their connections and interactions. The idea is that matchmaking functions are key components to find semantic compatibilities among independently Web service descriptions. To this end, our approach extends existing methods (Exact, Plug-in, Subsume, Intersection and Fail) with Concept Abduction to provide explanations of misconnections between Web services. From this we generate Web service compositions that realize the goal, discovering and satisfying semantic connections between Web services. Moreover a process of relaxing the hard constraints is introduced in case the composition process failed. Our system is implemented and interacting with Web services dedicated on a France Telecom scenario.

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A Framework for Multi-Platform SOA Security Analyses

Sam Weber,Paula Austel,Michael McIntosh — 9/28/2007 22:53

The myriad of SOA platforms and the complexity of the Web Services standards has meant that it is difficult for users to ensure that their deployments are appropriately secure. Despite the compilation of various SOA security "best practices", detecting violations of such practices has proven difficult.

To address this need, we developed a tool that can analyze the deployment configurations of multiple SOA platforms and report potential SOA best practice violations. In this paper, we compare, contrast and categorize SOA platforms, and describe the analysis challenges posed by each category. We describe our framework architecture for our multi-platform analyses, and further describe our prototype implementation of this architecture.

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Automated Functional Conformance Test Generation for Semantic Web Services

9/28/2007 22:54

We present an automated approach to generate functional conformance tests for semantic web services. The semantics of the web services are defined using the Inputs, Outputs, Preconditions, Effects (IOPEs) paradigm. For each web service, our approach produces testing goals which are refinements of the web service preconditions using a set of fault models. A novel planner component accepts these testing goals, along with an initial state of the world and the web service definitions to generate a sequence of web service invocations as a test case. Another salient feature of our approach is generation of verification sequences to ensure that the changes to the world produced by an effect are implemented correctly. Lastly, a given application incorporating a set of semantic web services may be accessible through several interfaces such as 1) Direct Invocation of the web services, or 2)a Graphical User Interface (GUI). Our technique allows generation of executable test cases which can be applied through both interfaces. We describe the techniques used in our test generation approach. We also present results which compare two approaches: an existing manual approach without the formal IOPEs information and the IOPEs-based approach reported in this paper. These results indicate that the approach described here leads to substantial savings in effort with comparable results for requirements coverage and fault detection effectiveness.

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Learning Ontologies to Improve the Quality of Automatic Web Service Matching

Hui Guo,Anca Ivan,Rama Akkiraju,Richard Goodwin — 9/28/2007 22:52

Automatically finding suitable Web services given a request is a difficult problem because the interface descriptions ofWeb services are often terse and cryptic. Dictionary and information retrieval based techniques have proven useful in disambiguating the semantics of service descriptions, but they are limited in their capability to consider the relationships between the words describing theWeb services. Current ontology-based approaches typically require a user to explicitly create domain ontologies. This paper presents a novel technique that significantly improves the quality of semantic Web service matching by (1) automatically generating ontologies based on Web service descriptions and (2) using these ontologies to guide the mapping between Web services. Our approach differs from earlier work on service matching by considering the relationship between words rather than treating them as a bag of unrelated words. The experimental results indicate that with our unsupervised approach we can eliminate up to 70% of incorrect matches that are made by dictionary-based approaches.

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Probabilistic QoS and soft contracts for transaction based Web services

Sidney Rosario,Albert Benveniste,Stefan Haar,Claude Jard — 9/28/2007 22:56

Web services orchestrations and choreographies require establishing Quality of Service (QoS) contracts with the user. This is achieved by performing QoS composition, based on contracts established between the orchestration and the called Web services. These contracts are typically stated in the form of hard guarantees (e.g., response time always less than 5 msec). In this paper we propose using soft contracts instead. Soft contracts are characterized by means of probability distributions for QoS parameters. We show how to compose such contracts, to yield a global contract (probabilistic) for the orchestration. Our approach is implemented by the TOrQuE tool. Experiments on TOrQuE show that overly pessimistic contracts can be avoided and significant room for safe overbooking exists.

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Efficient Implementation of XML Security for Mobile Devices

Jaakko Kangasharju — 9/03/2007 05:39

The population of mobile devices capable of participating in the Internet has increased dramatically in the last few years. To include this population into the Web service world requires support for the most important features, in particular security at the message level. This paper covers our approach to implement XML security specifications on mobile devices that allows efficient single-pass processing of XML encryption and signatures. Furthermore, we propose extensions to security specifications to better take into account the needs of mobile devices. We demonstrate the performance of our implementation, as well as our proposed extensions, through experiments, carried out in a real mobile environment.

A Stateful Web Service Firewall for BPEL

Nils Gruschka,Meiko Jensen,Norbert Luttenberger — 9/28/2007 22:58

Today, the Business Process Execution Language (BPEL) is the most emerging specification for Web Service Composition, which is an important part of the SOA paradigm. Defining a stateful communication protocol, BPEL enables potential for new security vulnerabilities. In this paper, we present a severe Denial-of-Service attack on a leading BPEL engine, illustrating new threats on availability in the context of BPEL. Derived from our observations, we developed a protection concept and implemented an application level firewall fending these types of attacks.

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Automatic Composition of SemanticWeb Services

Srividya Kona,Ajay Bansal,Gopal Gupta — 9/03/2007 06:01

Service-oriented computing is gaining wider acceptance. For Web services to become practical, an infrastructure needs to be supported that allows users and applications to discover, deploy, compose and synthesize services automatically. For this automation to be effective, formal semantic descriptions of Web services should be available. In this paper we formally define the Web service discovery and composition problem and present an approach for automatic service discovery and composition based on semantic description of Web services. We also report on an implementation of a semantics-based automated service discovery and composition engine that we have developed. This engine employs a multi-step narrowing algorithmand is efficiently implemented using the constraint logic programming technology. The salient features of our engine are its scalability, i.e., its ability to handle very large service repositories, and its extremely efficient processing times for discovery and composition queries. We evaluate our engine for automated discovery and composition on repositories of different sizes and present the results.

Improving the Performance of Web Services Using Deployment-Time Binding Selection

SangJeong Lee,Kyung Dong Ryu,Kang-Won Lee,Jong-Deok Choi — 9/03/2007 21:31

In this paper, we present a novel deployment-time binding selection framework for Web services to improve the performance. Using the information about target environments, we determine the best binding based on the availability and the accessibility of a service, and the performance characteristics of the bindings in a target environment. We have implemented the proposed mechanism as part of Eclipse-based development tools. We present an extensive performance evaluation of our methodology using benchmarks that we have created following public Web service interfaces, and emulating several e-business applications including a large scale legacy transaction processing system that runs on a mainframe.

A protocol for QoS contract negotiation and its implementation using Web Services

Helia Pouyllau,Stefan Haar — 9/28/2007 22:59

The way Internet is used changes: demand grows for critical services that cross several provider networks; guaranteeing a required end-to-end Quality of Service (QoS) across several networks becomes a challenge. Some critical services (e.g. video-conference, VPN etc.) can not be satisfied in a best effort fashion. The use of QoS contracts (Service Level Agreements, SLAs) is effective for management of such services. However, the problem of meeting end-to-end QoS requirement remains: no centralized entity can compute overall QoS for chains of contracts, and a fortiori, such contract chains can not be optimized centrally. Thus, the following problem has to be solved: given an endto- end QoS request and collections of available SLAs on each participating domain, establish an end-to-end contract committing a chain of providers and giving optimal service under most reliable guarantees available.

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Rich Services: The Integration Piece of the SOA Puzzle

9/28/2007 23:00

One of the key challenges to successful systems-of-systems integration using Web services technologies is how to address crosscutting architectural concerns such as policy management, governance, and authentication, while still maintaining the lightweight implementation and deployment Jlavor that distinguishes Web services fiom earlier attempts at providing interoperable enterprise systems.

To address this challenge, this article introduces the notion of a Rich Service, an extension of the standard service notion, based on an architectural pattern that allows hierarchical decomposition of system architecture according to separate concerns. Rich Services enable the capture of dzfferent system aspects and their interactions. By leveraging emerging Enterprise Service Bus technologies, Rich Services also enable a direct transition from a logical to a deployed service-oriented architecture (SOA). This results in immediate beneJits not only in SOA design, implementation, deployment, and quality assurance, but also in the traceability of architectural requirements to an SOA implementation.

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On Composing a Reliable Composite Web Service: A Study of Dynamic Web Service Selection

San-Yih Hwang,Ee-Peng Lim,Chien-Hsiang Lee,Cheng-Hung Chen — 9/28/2007 23:02

Dynamic web service selection refers to determining a subset of component web services to be invoked so as to orchestrate a composite web service. Previous work in web service selection usually assumes the invocations of web service operations to be independent of one another. This assumption however does not hold in practice as both the composite and component web services often impose some orderings on the invocation of their operations. Such orderings constrain the selection of component web services to orchestrate the composite web service. We therefore propose to use finite state machine (FSM) to model the invocation order of web service operations. We define a measure, called aggregated reliability, to measure the probability that a given state in the composite web service will lead to successful execution in the context where each component web service may fail with some probability. We show that the computation of aggregated reliabilities is equivalent to eigenvector computation. The power method is hence adopted to efficiently derive aggregated reliabilities. In orchestrating a composite web service, we propose two strategies to select component web services that are likely to successfully complete the execution of a given sequence of operations. Our experiments on a synthetically generated set of web service operation execution sequences show that our proposed strategies perform better than the baseline random selection strategy.

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On Context-Specific Substitutability of Web Services

Jyotishman Pathak,Samik Basu,Vasant Honavar — 9/28/2007 23:01

Web service substitution refers to the problem of identifying a service that can replace another service in the context of a composition with a specified functionality. Existing solutions to this problem rely on detecting the functional and behavioral equivalence of a particular service to be replaced and candidate services that could replace it. We introduce the notion of context-specific substitutability, where context refers to the overall functionality of the composition that is required to be maintained after replacement of its constituents. Using the context information, we investigate two variants of the substitution problem, namely environment-independent and environmentdependent, where environment refers to the constituents of a composition and show how the substitutability criteria can be relaxed within this model. We provide a logical formulation of the resulting criteria based on model checking techniques as well as prove the soundness and completeness of the proposed approach.

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A-SOAP: Adaptive SOAP Message Processing and Compression

Marcel-Catalin Rosu — 9/28/2007 23:03

Adaptive SOAP (A-SOAP) is a practical approach to SOAP message compression. A-SOAP separates mechanisms from policies and allows for incremental deployment. This paper focuses on its three underlying mechanisms: accelerating message composition, reducing parsing overheads, and compressing messages, which leverages the previous two mechanisms. In contrast to existing dictionary-based compression techniques, ASOAP does not require dictionaries to be exchanged between the two endpoints in advance; its dictionaries are built incrementally, as the communication progresses. ASOAP endpoints agree on the dictionary management policy using a mechanism similar to HTTP content negotiation, possibly using a dedicated HTTP header field. In experiments with short messages and a simple policy, an A-SOAP prototype reduces processing overheads by half and message sizes by an order of magnitude without increasing message latencies.

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Extending Web Services Semantics to Support Asynchronous Invocations and Continuation

Eugenio Zimeo,Giancarlo Tretola — 9/28/2007 23:04

Asynchronous invocation and continuation are common patterns in some middleware infrastructures for object-based distributed computing. Their benefits are particularly significant in distributed environments characterized by high communication latencies and coarse-grained operations. Therefore, Web Services could strongly benefit from the adoption of these patterns to (1) overlap communication with computation, (2) reduce the high number of interactions typically needed to handle stateless services by migrating the state of a service as parameters of service operations, (3) intercept at runtime data dependencies among consecutive services in a composition not visible from service descriptions. Unfortunately, current semantics of Web Services do not directly support the patterns, but some specifications (i.e. WS-Addressing) can simplify their implementation. In the paper we present the patterns, their benefits, and a module that implements a flexible schema useful to perform asynchronous invocations in several contexts. This way, modelling composed services can benefit from abstractions whilst more sophisticated low-level interactions among services are automatically handled at run-time.

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The Web Services-BusinessActivity-Initiator (WS-BA-I) Protocol: an Extension to the Web Services-BusinessActivity Specification

Hannes Erven,Georg Hicker,Christian Huemer,Marco Zaptletal — 9/28/2007 23:01

The Web Services Transaction protocol family includes the WS-AtomicTransaction and the WSBusinessActivity specifications in order to carry out distributed transactions in a Web Services (WS) environment. The WS-AtomicTransaction specification defines all necessary interfaces to carry out transactional work. In contrary, the WS-BusinessActivity specification for long-running transactions intentionally left the interface between initiator and coordinator undefined. This allows vendors to integrate WS-BusinessActivity coordinators into their business process engines. However, it requires proprietary protocols between initiator and coordinator. We propose an extension protocol to the WS-BusinessActivity specification that explicitly defines this interface between initiator and coordinator. This extension allows coordinators and initiators from different vendors to interoperate transparently. Accordingly, participants no longer need to trust an initiator-selected and likely initiator-run coordination service, but may use commonly trusted, third-party coordination services.

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Handling User Preferences and Added Value in Discovery of Semantic Web Services

Laszlo Kovacs,Andras Micsik,Peter Pallinger — 9/28/2007 23:06

This paper presents the discovery engine implemented for the INFRAWEBS project, which combines a traditional IR-based pre-filtering step and a logicbased matching implemented in Prolog. The logicbased step of discovery uses a novel technique based on Prolog-style unification of terms. This approach performs well in finding matches of intersection type, and it also provides possibilities to compare, rank and explain these matches. Furthermore, it can support matching and ranking based on users’ preferences compared to the added value offered by services.

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A Platform for Context Aware Runtime Web Service Discovery

George Spanoudakis,Khaled Mahbub,Andrea Zisman — 9/03/2007 21:56

In this paper we describe a platform that supports context aware runtime service discovery. The platform supports service discovery based on structural and behavioural service models as well as complex context related service discovery conditions which are specified in a newly introduced query language. During discovery, context information is obtained through a uniform scheme of calling "context operations" and is subsequently used in the evaluation of service discovery queries.

A Practical Approach to Web Service Discovery and Retrieval

Colin Atkinson,Philipp Bostan,Oliver Hummel,Dietmar Stoll — 9/28/2007 23:07

One of the fundamental pillars of the web service vision is a brokerage system that enables services to be published to a searchable repository and later retrieved by potential users. This is the basic motivation for the UDDI standard, one of the three standards underpinning current web service technology. However, this aspect of the technology has been the least successful, and the few web sites that today attempt to provide a web service brokerage facility do so using a simple cataloguing approach rather than UDDI. In this paper we analyze why the brokerage aspect of the web service vision has proven so difficult to realize in practice and outline the technical difficulties involved in setting up and maintaining useful repositories of web services. We then describe a pragmatic approach to web service brokerage based on automated indexing and discuss the required technological foundations. We also suggest some ideas for improving the existing standards to better support this approach and web service searching in general.

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Reputation-Enhanced QoS-based Web Services Discovery

Ziqiang Xu,Patrick Martin,Wendy Powley,Farhana Zulkernine — 9/28/2007 23:08

With an increasing number of Web services providing similar functionalities, Quality of Service (QoS) is becoming an important criterion for selection of the best available service. Currently the problem is twofold. The Universal Description, Discovery and Integration (UDDI) registries do not have the ability to publish the QoS information, and the authenticity of the advertised QoS information available elsewhere may be questionable.

We propose a model of reputation-enhanced QoSbased Web services discovery that combines an augmented UDDI registry to publish the QoS information and a reputation manager to assign reputation scores to the services based on customer feedback of their performance. A discovery agent facilitates QoS-based service discovery using the reputation scores in a service matching, ranking and selection algorithm. The novelty of our model lies in its simplicity and in its coordination of the above mentioned components. We present experiments to evaluate the effectiveness of our approach using a prototype implementation of the model.

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Inverted Indexing for Composition-Oriented Service Discovery

Li Kuang,Ying Li,Jian Wu,Shuiguang Deng,Zhaohui Wu — 9/03/2007 21:59

Service discovery becomes a key to hastening the evolution of web services as the number of services is expected to increase dramatically. In this paper, we propose to index all the ontology-annotated outputs in registered services. For each ontology-annotated output, there is a service list which records all the services in the registry that deliver the output. Based on the indexing, we propose a composition-oriented service discovery algorithm, which greatly accelerates the filtering of irrelevant atomic services by making use of the inverted indexing, and increases the likelihood of finding a possible candidate by exploring service composition. Experimental results show that the proposed algorithm provides a better performance on response time than the sequential matchmaking, and a better recall rate than the algorithms without the exploration of composition.

Web Service Discovery Using General-Purpose Search Engines

Henry Song,Doreen Cheng,Alan Messer,Swaroop Kalasapur — 9/28/2007 23:10

WSDL provides the potential for Web Services to enrich consumers’ lives. However, it has had only limited success in enterprise environments and even less in the mass market. Apart from the difficulties and high costs involved in current approaches, another reason is the low precision for Web Services discovery using the most widely known tool: search engines. Seeking for effective ways to change the situation, we conducted an experiment to examine better approaches of using general-purpose search engines to discover Web Services. We used nine different approaches for publishing Web Services and two groups of total 18 queries for retrieving them using Yahoo and Google search engines. The queries were fired to each search engine daily over a week and the top 100 search results returned from every search are collected and analyzed. The results show that for both search engines, embedding a WSDL specification in a Web page that provides semantic description of the service yield the best results.

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A Declarative Approach to Enhancing the Reliability of BPEL Processes

An Liu,Qing Li,Mingjun Xiao — 9/03/2007 22:08

Currently, BPEL is the de-facto standard for the web service composition. Because web services are autonomous and loosely coupled, BPEL processes are susceptible to a wide variety of faults. However, BPEL only provides limited constructs for handling faults, which makes fault handling a time-consuming and error-prone task. In this paper, we propose a declarative approach to enhancing the reliability of BPEL processes. Our solution specifies fault handling logic through a set of Event- Condition-Action (ECA) rules which build on an extensible set of fault-tolerant patterns. These ECA rules are integrated with normal business logic before deployment to generate a fault-tolerant BPEL process. We also develop a GUI tool to assist designers to specify ECA rules. Experiments show our approach is feasible.

ANGEL: Optimal Configuration for High Available Service Composition

Huipeng Guo,Jinpeng Huai,Huan Li,Ting Deng,Yang Li,Zongxia Du — 9/28/2007 23:11

With the fast development of Internet and rapid acceptance of Web Service technology, more and more service resources have emerged. Service composition which integrates the functionalities of different services is a promising technique for developing applications across multiple organizations. However, in a distributed, dynamic and autonomous environment, such as a service composition-based system, the availability and reliability are big concerns in terms of nonfunctional properties. In this paper, we propose a novel service composition method, ANGEL, with the target of the improvement of system availability. We adopt redundant mechanism in ANGEL and propose a model to improve the property of the service availability. We model the multiple services selection problem based on redundant mechanism as a nonlinear mixed integer programming problem and therefore, we propose two heuristic algorithms to select multiple feasible services that have the same functions, but with better availability. In order to maintain the availability of composite services, we further introduce monitor and detection mechanisms. Through the comprehensive experiments, we find that our proposed techniques can indeed achieve better availability as expected.

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Scale-Free Web Services

Hong Cai — 9/28/2007 23:09

The development of the Internet and Web 2.0 eased communication among people and triggered the flourish of Web based communities. Among them, there are blog, social networks, music networks, and recommendation network, etc. There are also communities of massively multiplayer online games. In particular, 3D based virtual worlds, like Second Life, are highly welcomed by people. Users contribute to these communities while at the same time obtain value from the communities instead of passive browsing. The relationships among the community members and community services could be represented by different types of networks. The topology of networks influence the way how people interact and information spread within the community. In this paper, we propose a mechanism to facilitate the communities to grow into scale-free networks. Scale-free communities have good properties that could potentially speed up its accumulation of value for both the members and the community itself. We extend WSDL into Scale-Free Web Services using Web Services Resource Framework.

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BPEL4Chor: Extending BPEL for Modeling Choreographies

Gero Decker,Oliver Kopp,Frank Leymann,Mathias Weske — 9/28/2007 23:12

The Business Process Execution Language (BPEL) is a language to orchestrate web services into a single business process. In a choreography view, several processes are interconnected and their interaction behavior is described from a global perspective. This paper shows how BPEL can be extended for defining choreographies. The proposed extensions (BPEL4Chor) distinguish between three aspects: (i) participant behavior descriptions, i.e. control flow dependencies in each participant, (ii) the participant topology, i.e. the existing participants and their interconnection using message links and (iii) participant groundings, i.e. concrete configurations for data formats and port types. As BPEL itself is used unchanged, the extensions facilitate a seamless integration between service choreographies and orchestrations. The suitability of the extensions is validated by assessing their support for the Service Interaction Patterns.

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Dynamic Web Service Composition within a Service-Oriented Architecture

Ivan J. Jureta,Stephane Faulkner,Youssef Achbany,Marco Saerens — 9/03/2007 22:17

Increasing automation requires open, distributed, service-oriented systems capable of multicriteria-driven, dynamic adaptation for appropriate response to changing operating conditions. We combine a simple architecture with a novel algorithm to enable openness, distribution, and multi-criteria-driven service composition at runtime. The service-oriented architecture involves mediator web services coordinating other web services into compositions necessary to fulfil user requests. By basing mediator services’ behavior on a novel multicriteria-driven (including quality of service, deadline, reputation, cost, and user preferences) reinforcement learning algorithm, which integrates the exploitation of acquired knowledge with optimal, undirected, continual exploration, we ensure that the system is responsive to changes in the availability of web services. The reported experiments indicate the algorithm behaves as expected and outperforms two standard approaches.

Haley: A Hierarchical Framework for Logical Composition ofWeb Services

Haibo Zhao,Prashant Doshi — 9/28/2007 23:13

Prevalent approaches for automatically composing Web services (WSs) into Web processes predominantly utilize planning techniques to achieve the composition. However, many of the planning methods do not scale efficiently to large processes. In addition, they lack the capability to operate directly on the WS descriptions, and specifically on the preconditions and effects which may be represented using first order logic based languages. Instead, many of these methods ground and propositionalize the higher level logic resulting in exponentially many more states. In this paper, we present a new framework for composing Web services into processes, called Haley, that exploits the natural hierarchy often found in Web processes. Haley uses symbolic techniques that operate directly on first order logic based representations of the state space to obtain the compositions. In addition to providing an approach that handles the uncertainty inherent in Web services, Haley guarantees cost-based optimality and offers an approach potentially scalable to large real world processes.

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Model-driven Composition of Context-aware Web Services Using ContextUML and Aspects

George N. Prezerakos,Nikolaos D. Tselikas,Giovanni Cortese — 9/28/2007 23:15

Service Oriented Architectures (SOAs) are constantly gaining ground for the provision of business to business as well as user-centric services, mainly in the form ofWeb Services technology. SOAs enable service providers to design and deploy new,composite service offerings out of existing component services. In order to match end-user expectations with respect to personalization and ease of use, these services should be designed in a manner that allows them to exhibit a certain level of context-awareness which is a basic element towards a richer end-user experience. However, in the majority of such services, context-handling is still tightly coupled with the core functionality of the service, resulting in a design which is difficult to implement and maintain. The paper proposes the decoupling of core service logic from context-related functionality by adopting a Model-driven approach based on a modified version of the ContextUML metamodel. Core service logic and context handling are treated as separate concerns at the modeling level as well as in the resulting source code where Aspect Oriented Programming (AOP) encapsulates contextdependent behavior in discrete code modules. The design of a restaurant finder service is used to portray the modified ContextUML metamodel and the service modeling process which is covered in full. Respective code snippets belonging to the executable version of the service (part of work in progress) are also provided, illustrating the transition from model to code and the resulting separation of concerns.

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An Approach to Debugging Grid or Web Services

Qiang YUE,Zhiwei XU,Haiyan YU,Wei LI,Li ZHA — 9/28/2007 23:16

In this paper, we first introduce some issues that are encountered in building a service debugger and briefly describe our approach to addressing them. Next, we outline some debugging modes and components of a simple composite debugger. Then, we mainly describe its message-based front-end and back-end, which are a co-existing, self-identifying, and non-intrusive. Finally, we preset some experimental results of our latest prototype.

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A Model to support SPKI Federations management through XKMS

9/28/2007 23:17

The purpose of the XML Key Management Specification (XKMS) is to facilitate the use of a Public Key Infrastructure (PKI) by transferring the complexity associated with PKI to a trusted Web Service. Although this specification contains information on how compatibility with PKIs such as PGP and SPKI/SDSI can be reached, it is straight focused on X.509 PKI. This work uses XKMS to define a federated management model for SPKI/SDSI. In a web of SPKI Federations, the proposed model follows a peer-to-peer approach for discovering and establishing certificate chains. This model introduces a search algorithm and its effectiveness was verified through simulations.

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A Hierarchical Model for TransactionalWeb Service Composition in P2P Networks

Joyce El Haddad,Maude Manouvrier,Marta Rukoz — 9/28/2007 23:28

The recent approaches for Web services composition tend to integrate heterogeneous business processes executed in Peer-to-Peer networks. In such networks, componentWeb services are invoked on independent peers and are orchestrated according to the transactional requirements defined by the designers or the users of the composite Web service. Since component Web services can be dynamically invoked and are generally implemented as black boxes, concurrency between them may appear. This paper presents the transactional execution model of compositeWeb services exploiting the transactional properties of their component Web services. The proposed concurrency control is ensured by a decentralized serialization graph based on an optimistic protocol and on the hierarchical structure of the composition. The globally correct execution of the composite Web service is achieved by communication among dependent subtransactions and the peers they have accessed.

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Requirements-driven Verification of WSBPEL Processes

Mohsen Rouached,Claude Godart — 9/03/2007 22:26

Current Web services composition proposals, such as BPML, WSBPEL, WSCI, and OWL-S, provide solutions for describing the control and data flows in Web service composition. However, such proposals remain at the descriptive level, without providing any kind of mechanisms or tool support for analysis and verification. Therefore, there is a growing interest for the verification techniques which enable designers to test and repair design errors even before actual running of the service, or allow designers to detect erroneous properties and formally verify whether the service process design does have certain desired properties.

In this paper, we propose to verify Web services composition using an event driven approach. We assume Web services that are coordinated by a composition process expressed in WSBPEL and we use Event Calculus to specify the properties and requirements to be monitored.

Automated Choreographer Synthesis for Web Services Composition Using I/O Automata

Saayan Mitra,Ratnesh Kumar,Samik Basu — 9/28/2007 23:29

We study the problem of synthesis of a choreogrpher in Web service composition for a given set of services and a goal. Services and goal are represented using i/o automata which can succinctly and precisely describe the interfaces of the services. Our technique considers existence and synthesis of two types of the choreographers: a simple choreographer capable of only relaying outputs from one service to input of another and a transducing choreographer which is capable of storing and reusing inputs/outputs from the services. The central theme of our technique relies on generating i/o automata representation of all possible choreographed behavior of existing services (captured in form of universal service automaton, a concept introduced in this paper) and verifying that the goal can be simulated by the universal set of choreographed behaviors.

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Web Services Methods for Communication over IP

Wu Chou,Li Li,Feng Liu — 9/28/2007 23:18

In this paper, we study web services methods and approaches to enable real-time communication services over IP. This approach extends web services methodologies from service integration to a serviceoriented approach for communication. In particular, we describe the generic web service based application session management, WS-Session, the two-way full duplex web service interaction framework, and most importantly, the development of Web Service Initiation Protocol (WIP) which is a full featured web service and SOA based communication framework for multimedia and voice communication over IP. We show that WIP provides a service oriented architecture which can be extended seamlessly from a P2P endpoint to an endpoint with advanced call control and switching capabilities typically requiring the assistance of a dedicated PBX. A prototype of WIP system is fully developed. Architectural design and system implementation of web service based communication endpoints are studied and applied to realize service-oriented communication over IP. Advances of WIP indicate the beginning of a full web service and SOA based communication paradigm that can reshape the converged communication over IP.

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An Exploratory Study of Web Services on the Internet

Yan Li,Yao Liu,Liangjie Zhang,Ge Li,Bing Xie,Jiasu Sun — 9/28/2007 23:30

Web services technology has received much attention in the last few years, and a lot of research efforts have been devoted to utilizing services on the Internet to fulfill consumers’ requirements. However, little research has been done on the current status of web services on the Internet, which has a great impact on current research. Enlightened by this situation, we made an exploratory study of the current status of web services on the Internet. Our study mainly focused on the investigation of four aspects, including the number, complexity, quality of description and the function diversity of available web services on the Internet. A web services investigation system is built up to harvest web services from the Internet and calculate the statistical results. The investigation results are reported in this paper, and, based on our study, the development trend of web services technology is also discussed in this paper.

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Comparing Web Services with other Software Components

Yijun Yu,Jianguo Lu,Juan Fernandez-Ramil,Phil Yuan — 9/28/2007 23:32

Software metrics are vital for the management of software development, especially when a new technology is being adopted and established practices have yet to emerge. As a kind of software components, web service technology has flourished and attracted a flurry of research activities. Despite the vast amount of research on mechanisms of web services, there have been little investigations of the overall nature of existing web services from a software component point of view. This paper is the first attempt to compare web services with other software components in terms of established metrics in software engineering, including object oriented metrics and interface metrics. In this study we conclude that there are statistical differences between the interface, variable name and other OO metrics when one compares a large sample of web services with typical OO systems. The distributions obtained give insight into the typical characteristics of web services and can be used to identify candidates for wrapping into web services.

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A Self-Healing Framework for Web Services

Henri Naccache,Gerald C. Gannod — 9/28/2007 23:34

Ajax-based web applications are designed to mimic more traditional desktop applications and require quick response times from the underlying Web services. However, since availability and performance of Web services cannot be guaranteed, response time and overall performance of Ajax-based applications can vary. In this paper we describe a framework for developing autonomic self-healing Web service-based applications that rely on the notion of differentiated services (i.e., services that provide common behavior with variable quality of service) in order to maintain required performance characteristics. We present the expected impact of the framework through the use of a theoretical QN model, demonstrate the framework with an example, and provide an evaluation of the technique.

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A Version-aware Approach for Web Service Directory

Ru Fang,Linh Lam,Liana Fong,David Frank,Christopher Vignola,Ying Chen,Nan Du — 9/28/2007 23:35

In real-world scenarios, the evolution of Web services to meet functional and non-functional changes ultimately leads to multiple versions of the same original service. Thus, design and implementation of version management techniques, such as version description, directory, etc, play a critical role in realizing the full promise of SOA. To address the version management issues in Web services, we propose a version-aware service model based on some architectural extensions to WSDL and UDDI. WSDL would be enhanced to describe the attributes of the service versions. UDDI would be augmented to use versions in a service directory with an event-based notification/subscription mechanism. We also design a proxy, residing in the service consumer side which can dynamically update the client application instance at runtime. We have implemented a prototype to demonstrate these models and used a weather forecast web service as an example to illustrate the usefulness of the proposed architecture.

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Autonomic Web Service Platform with Dynamic Multi-Layer Control

9/28/2007 23:36

The rapid expansion of Web services and broadband network has enabled more and more useful services for the users with different systems at distributed locations to share applications over the network. However, the operation of such services has become more and more difficult in proportion to the complexity of the total system with applications and networks that need to be managed. Therefore, it requires a lot of effort for the operators to manage the total system if some trouble occurred with an application or a network.

This paper presents an autonomic Web service platform with the dynamic multi-layer control that can manage both the network layer and the application layer simultaneously to offer the most preferred service for the users under any circumstances. It consists of three major components: 1) Environment Information Database, which stores the status of networks and applications, 2) Dynamic Control Manager, which maintains service policies on both networks and applications, and controls the service delivery based on the service policy that conforms to the current situation, 3) Dynamic Control Agent, which works as a Web service proxy and controls SOAP messages of the applications based on the service policy.

The communications and controls of this platform are all Web services based, and therefore, are quite open and applicable to any field of services. The result of an experiment on the disaster information sharing service proved the effectiveness of this Web service platform.

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Utility-based QoS Brokering in Service Oriented Architectures

Daniel A. Menasce,Vinod Dubey — 9/28/2007 23:37

Quality of Service (QoS) is an important consideration in the dynamic service selection in the context of Service Oriented Architectures. This paper extends previous work on QoS brokering for SOAs by designing, implementing, and experimentally evaluating a service selection QoS broker that maximizes a utility function for service consumers. Utility functions allow stakeholders to ascribe a value to the usefulness of a system as a function of several attributes such as response time, throughput, and availability. This work assumes that consumers of services provide to a QoS broker their utility functions and their cost constraints on the requested services. Service providers register with the broker by providing service demands for each of the resources used by the services provided and cost functions for each of the services. Consumers request services from the QoS broker, which selects a service provider that maximizes the consumer’s utility function subject to its cost constraint. The QoS broker uses analytic queuing models to predict the QoS values of the various services that could be selected under varying workload conditions. The broker and services were implemented using a J2EE/Weblogic platform and experiments were conducted to evaluate the broker’s efficacy. Results showed that the broker adequately adapts its selection of service providers according to cost constraints.

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Performance Evaluation and Modeling of Web Services Security

Shiping Chen,John Zic,Kezhe Tang,David Levy — 9/03/2007 22:56

While Web Services Security (WSS) enhances the security of web services, it may also introduce additional performance overheads to standard web services due to additional CPU processing and larger messages transferred. In this paper, we aim at clarifying this concern by conducting a quantitative performance evaluation of WSS overhead. Based on the evaluation, we extend our existing web services performance model by taking the extra WSS overheads into account. The extended performance model is validated on different environments with different messages sizes and WSS security policies.

Personalized QoS Prediction forWeb Services via Collaborative Filtering

Lingshuang Shao,Jing Zhang,Yong Wei,Junfeng Zhao,Bing Xie,Hong Mei — 9/28/2007 23:38

Many researchers propose that, not only functional but also non-functional properties, also known as quality of service (QoS), should be taken into consideration when consumers select services. Consumers need to make prediction on quality of unused web services before selecting. Usually, this prediction is based on other consumers’ experiences. Being aware of different QoS experiences of consumers, this paper proposes a collaborative filtering based approach to making similarity mining and prediction from consumers’ experiences. Experimental results demonstrate that this approach can make significant improvement on the effectiveness of QoS prediction for web services.

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A Policy-Based Authorization Framework for Web Services: Integrating XGTRBAC and WS-Policy

Rafae Bhatti,Daniel Sanz,Elisa Bertino,Arif Ghafoor — 9/28/2007 23:37

Authorization and access control in Web services is complicated by the unique requirements of the dynamic Web services paradigm. Current authentication mechanisms for Web services do not differentiate between users in terms of fine-grained access privileges. This results in an all-or-nothing access which is not flexible enough for modern day business processes using Web services to execute. In this paper, we present a policy-based authorization framework to address this requirement. We have designed a profile of the well-known WS-Policy specification tailored to meet the access control requirements in Web services by integrating WS-Policy with an access control policy specification language, X-GTRBAC. The design of the profile is aimed at bridging the gap between available policy standards for Web services and existing policy specification languages for access control. The profile supports the WS-Policy Attachment specification, which allows separate policies to be associated with multiple components of a Web service description, and one of our key contributions is the design of an algorithm to compute the effective policy for the Web service given the multiple policy attachments. To allow Web service applications to use our solution, we have adopted a component-based design approach based on well-known UML notations. We have also prototyped our architecture, and implemented it as a loosely coupled Web service providing healthcare information services to physicians subject to applicable authorization policies.

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Guarding Sensitive Information Streams through the Jungle of Composite Web Services

Jinpeng Wei,Lenin Singaravelu,Calton Pu — 9/28/2007 23:40

Complex and dynamic web service compositions may introduce unpredictable and unintentional sharing of security-sensitive data (e.g., credit card numbers) as well as unexpected vulnerabilities that cause information leak. This paper describes a fine-grain access policy specification of security-sensitive data items for each component web service. We propose the SFGuard architecture to enforce these access policies at component web services. A prototype implementation of SF-Guard (on Apache Axis2) and its evaluation show that effective protection of security-sensitive information can be achieved at low overhead (a few percent addition to response time) while preserving the functionality of flexible web service composition.

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An Operational Model and Language Support for Securing Web Services

Gwan-Hwan Hwang,Yu-Hsuan Chang,Tao-Ku Chang — 9/28/2007 23:41

In this paper, we propose an operational model to support the security of Web services. In addition to satisfying the basic security requirements, including authentication, confidentiality, data integrity, and nonrepudiation, the proposed model supports security mechanisms such as element-wise encryption and temporal-based element-wise digital signatures. Furthermore, the proposed model supports a flexible key specification scheme called explicit key definition, which can be used to define three different types of keys: static keys, dynamically selected keys, and keys applied to digital signatures. The service requester can determine the identity of the keys used without negotiating with the service provider. The implementation and experimental results demonstrate the feasibility of the proposed system.

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SOAP-based Secure Conversation and Collaboration

Mohammad Ashiqur Rahaman,Andreas Schaad — 9/28/2007 23:42

Web services in different trust boundaries interact with each other via SOAP messages to realize functionality in a collaborative environment. Exchanging SOAP messages for remote service invocation has gained wide acceptance among web service developers. Several web service security standards are widely deployed aiming at securing exchanges of a single SOAP message and a conversation of SOAP messages among partners in a collaborative environment. Concerns have been raised about the possibility of XML rewriting attacks within this context and their early detection.

In this paper, we demonstrate such possible attacks with respect to WS* policy based scenarios to set a security context and to use a security context for conversations of SOAP messages. We show how our proposed SOAP Account [21] solution could be applied for early detection of XML rewriting attacks, specifically regarding secure SOAP-based conversations. A simulation-based performance analysis and comparison of our SOAP Account approach vs. a WS* policy based approach complements our observations.

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Reasoning about Events to Specify Authorization Policies forWeb Services Composition

Mohsen Rouached,Claude Godart — 9/28/2007 23:43

Availability of a wide variety of Web services over the Internet offers opportunities of providing new value added services built by composing them out of existing ones. By integrating individual existing Web services the technology enables the provision of advanced and sophisticated services, such as allowing users to use different types of resources and services simultaneously in a simple procedure. However the management and maintenance of a large number of Web services is not easy and, in particular, needs appropriate authorization policies to be defined so as to realize reliable and secure Web Services. The required authorization policies can be quite complex, resulting in unintended conflicts, which could result in information leaks or prevent access to information needed. This paper proposes a logic based approach using for specifying authorization policies and detecting conflicts resulting from the combination of various kinds of authorization and constraint policies used in Web services environments. The method not only enables static detection of policy conflicts but also yields information that is helpful for correcting the policies. An automated induction-based theorem prover SPIKE is used as verification back-end.

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Towards Secure Execution Orders for CompositeWeb Services

Joachim Biskup,Barbara Carminati,Elena Ferrari,Frank Muller,Sandra Wortmann — 9/28/2007 23:43

Recently, there has been a growing interest in web service composition and the related security issues. In this paper, we propose a framework for the decentralized execution of composite web services capable to ensure the correctness as well as the security of the execution. Our framework relies on a data structure, called container, which is passed among the web services participating in the composition. The container is encrypted and authenticated in such a way to ensure the correctness of the execution flow as well as a set of relevant security requirements.

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Verifying the Consistency of Security Policies by Abstracting into Security Types

Kouichi Ono,Yuichi Nakamura,Fumiko Satoh,Takaaki Tateishi — 9/28/2007 23:45

The Service-Oriented Architecture (SOA) makes application development easier, because applications can be built from existing services with a bottom-up methodology. However, it is difficult to determine if a desired new service can be built from existing services. Not only the functional consistency of the existing services, but also the consistency of their non-functional (such as security) aspects must be verified. Message protection is an aspect of security. Every service needs an appropriate security policy defining the protection of messages exchanged between the parties to the service. Because of the intricacy of the Web Services Security Policy Language, it is difficult to verify the consistency of the security policies.

We are developing a method to verify the consistency of security policies by abstracting them. Each security policy is abstracted, and then attached as a security type to the corresponding service in the application model. The security type denotes a security level for message protection. The security developer defines the possible abstraction methods. In this paper, we define the constraint of abstraction methods based on the semantics of the policy language. And also we state verifying the consistemcy of security types by using information flow analysis.

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ServiceJ A Java Extension for ProgrammingWeb Services Interactions

Sven De Labey,Marko van Dooren,Eric Steegmans — 9/28/2007 23:46

Object-oriented programming languages are losing pace with the rapidly evolving Web Services paradigm. They are unable to deal with the distributed, volatile nature of web services, and they lack expressive language constructs for complex web service interactions. In this paper, we present ServiceJ, a Java extension with integrated support for web service programming. By extending the type system with type qualifiers, ServiceJ realizes important objectives from both paradigms. On one hand, ServiceJ resembles Java by promoting reuse and abstraction, and by supporting typesafe web service invocations. On the other hand, ServiceJ supports late web service binding, Quality of Service negotiation, and transparent web service failover.

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Generic Security Policy Transformation Framework for WS-Security

Fumiko Satoh,Yumi Yamaguchi — 9/28/2007 23:48

Model-Driven Security is a framework to configure WS-Security easily. It generates a security policy written in WS-SecurityPolicy to be transformed into platformspecific configuration files. Since the WS-SecurityPolicy specification is quite complicated, it is difficult to directly map between a security policy and a configuration. We propose a generic security policy transformation framework using an intermediate model. The intermediate model structure is designed based on the WS-Security message structure, because both a security policy and the configuration files correspond to one WS-Security message, even though the WS-SecurityPolicy is flexible in specifying security requirements. Our contributions are simpler transformation rules compared to direct mapping, the support for various platforms, and more flexible updates if the WS-SecurityPolicy specification changes. We demonstrate the transformation using the intermediate model for WebSphere Application Server 6.0.

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Specifying Semantic Web Service Compositions using UML and OCL

John T. E. Timm,Gerald C. Gannod — 9/28/2007 23:49

The semantic web promises to bring automation to the areas of web service discovery, composition and invocation. In order to realize these benefits, rich semantic descriptions of web services must be created by the software developer. A steep learning curve and lack of tool support for developing such descriptions thus far have created significant adoption barriers for semantic web service technologies. In this paper, we present a model-driven architecture based approach for specifying semantic web service compositions through the use of a UML profile that extends class and activity diagrams. This profile is used in transformations that facilitate automatic construction of OWL-S specifications from UML diagrams. Conditions required by the composition, such as those on control constructs, are specified using OCL and transformed into SWRL during the construction process.

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Describing Semantic Web Services: From UML to OWL-S

Il-Woong Kim,Kyong-Ho Lee — 9/28/2007 23:51

As a de facto standard, OWL-S enables the semantic description of Web services, resulting in the automated discovery, selection, and composition of Web services. However, the complexity of the OWL-S grammar makes it difficult to construct an OWL-S ontology manually. This paper presents an efficient method for generating OWL-S ontologies from UML diagrams, which are widely used for software design and development. The proposed method uses a class diagram to represent a domain ontology and sequence or activity diagrams to represent the behavior of a business process. It also uses UML profiles to support various features of OWL-S. Finally, an XMI file extracted from UML diagrams is transformed into an OWL-S ontology via an XSLT script. Experimental results with a large volume of UML diagrams show that the proposed method deals with the control flow of complex processes and is superior to previous methods.

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A Semantic Web Services-based Infrastructure for Context-Adaptive Process Support

Stefan Dietze,Alessio Gugliotta,John Domingue — 9/28/2007 23:51

Current technologies aimed at supporting processes whether it is a business or learning process - primarily follow a metadata- and data-centric paradigm. Whereas process metadata is usually based on a specific standard specification - such as the Business Process Modeling Notation (BPMN) or the IMS Learning Design Standard the allocation of resources is done manually at design-time, and the used data is often specific to one process context only. These facts limit the reusability of process models across different standards and contexts. To overcome these issues, we introduce an innovative Semantic Web Service-based framework aimed at changing the current paradigm to a context-adaptive service-oriented approach. Following the idea of layered semantic abstractions, our approach supports the development of abstract semantic process model - re-usable across different contexts and standards - that enables a dynamic adaptation to specific actor needs and objectives. To illustrate the application of our framework and establish its feasibility, we describe a prototypical application in the E-Learning domain.

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A Semantic Framework for Identifying Events in a Service Oriented Architecture

Karthik Gomadam,Ajith Ranabahu,Lakshmish Ramaswamy,Amit P. Sheth,Kunal Verma — 9/28/2007 23:52

We propose a semantic framework for automatically identifying events as a step towards developing an adaptive middleware for Service Oriented Architecture (SOA). Current related research focuses on adapting to events that violate certain non-functional objectives of the service requestor. Given the large of number of events that can happen during the execution of a service, identifying events that can impact the non-functional objectives of a service request is a key challenge. To address this problem we propose an approach that allows service requestors to create semantically rich service requirement descriptions, called semantic templates. We propose a formal model for expressing semantic templates and for measuring the relevance of an event to both the action being performed and the nonfunctional objectives. This model is extended to adjust the relevance of the events based on feedback from the underlying adaptation framework. We present an algorithm that utilizes multiple ontologies for identifying relevant events and present our evaluations that measure the efficiency of both the event identification and the subsequent adaptation scheme.

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On communication and coordination issues of Semantic Web Services

Omair Shafiq,Michal Zaremba,Dieter Fensel — 9/28/2007 23:54

Semantic Web Services have been envisioned in the form of different conceptual models like OWL-S, WSMO and WSDL-S. Web Services Execution Environment (WSMX) is our reference implementation for Semantic Web Service conceptual model, WSMO. In this paper, we have investigated the communication problems that Semantic Web Services systems are facing. We have proposed how to overcome these problems by using Triple Space Computing as an extended space-based computing paradigm for Semantic Web data. We have proposed the usage of Triple Space Computing to improve the internal communication and coordination during the process of execution of Semantic Web Services. We also have presented and analyzed the experimental results to demonstrate the effectiveness of our solution.

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A Dynamic Concept Interpretation Approach for OWL Extension

Shun Jiang,Chunhua Tian,Feng Li,Hao Zhang,Wei Ding — 9/28/2007 23:55

To add descriptive ability to knowledge representation (KR) system based on OWL, many extensions to OWL are proposed to augment its expressive power. Many of these extensions take the approach by changing the syntax and semantic of the description logic corresponding to OWL. A new approach is proposed in this paper by using a dynamic concept interpretation method without changing the structure of original description logic. This approach provides a flexible extension mechanism outside the description logic framework, which will not bring any additional logical computational complexity or uncertainty to the original description logic. And various implementations can be realized through this approach for different extension purposes.

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A SOA Approach to Counter DDoS Attacks

Xinfeng Ye,Santokh Singh — 9/28/2007 23:56

Distributed denial-of-service (DDoS) attacks are increasingly mounted by cyber-criminal gangs to extort money from online businesses. This kind of attacks is normally targeted at a particular service provider to exhaust the network and system resources of the provider. Since the scale of the attack is limited, the ISP operators normally cannot observe this type of attacks. As a result, the victim of the attack is left to deal with the attack on its own accord. This paper proposes a SOA approach to build a system against DDoS attacks targeting online businesses. The system is built on web services. It can be constructed and reconfigured easily by an attack victim. Experiments were also carried out to measure the overheads and the effectiveness of the proposed approach.

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A Web Service Recommender System Using Enhanced Syntactical Matching

M. Brian Blake,Michael F. Nowlan — 9/28/2007 23:57

Service-oriented computing (SOC) enables organizations and individual users to discover openly-accessible capabilities realized as services over the Internet. However, service registries can potentially be very large preventing organizations from discovering services in real-time. In fact, consumers may not be aware of the services that can be of most benefit to them. In our work, we introduce a web service recommender system that proactively discovers and manages web services. This paper focuses on the underlying search and ranking algorithms that enable the recommendations. As an innovation, we have analyzed real, fully-operational web services currently available on the Internet and, as a result, have discovered insights into how real web service messages are defined. Using these general naming tendencies coupled with enhanced syntactical methods, we are able to aggregate services by their messages and accurately suggest candidate services to users as a part of daily routines.

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Hosting Web Services on Resource Constrained Devices

Muhammad Asif,Shikharesh Majumdar,Raluca Dragnea — 9/28/2007 23:58

Web services are getting popular in the domain of business to business electronic commerce and in automating information exchange between business processes. The use of handheld devices such as PDAs and smart phones is spreading rapidly in the business community. Accessing web services from small devices is very common these days, but there is hardly any solution available to host web services on such devices. There are a number of challenges to host a web service on handheld device. These include limited resources and the lack of the execution environment to host web services. Because of the resource constraints, it is not possible to use the existing web service provider toolkits to host the web service. In this paper, a light weight web service provider toolkit is proposed that can be used for a variety of handheld devices. The insights gained into this web service provider system are discussed in detail.

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Axis2-based Replication Middleware forWeb Services

Johannes Osrael,Lorenz Froihofer,Martin Weghofer,Karl M. Goeschka — 9/28/2007 23:58

Dependability is one of the most important challenges for service-oriented architectures if their success shall continue in critical settings such as air traffic control or finance and banking. Replication of services and the underlying resources is one of the primary fault tolerance techniques for achieving dependability. While replication is well known in traditional fields (e.g. databases), it is rather in its infancy in service-oriented environments. Thus, in order to reduce the dependability gap we are currently facing in service-oriented environments, we contribute with a replication middleware for Web services which is built upon the Java-based Axis2 SOAP engine and provides a variant of primary-backup replication. Performance evaluations of our middleware implementation show the relatively low overhead of replication if the number of replicas is small.

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Delivering Promises for Web Services Applications

Julian Jang,Alan Fekete,Paul Greenfield — 9/29/2007 01:52

Among the problems facing designers of complex multi-participant Web services-based applications is dealing with the consequences of the lack of suitable isolation mechanisms. This deficiency means that concurrent applications can interfere with each other, resulting in race conditions and lost updates. This paper considers a proposed solution to this problem based on ‘promises’ and shows that this model can be implemented in practice. We consider implementation issues that need to be handled in promise-based systems and discuss a proof-of-concept prototype that supports promise-based isolation without requiring changes to existing applications and resources.

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An Aspect Oriented Approach for Applying Features to Web Services

Valery Abu-Eid — 9/03/2007 23:58

Web services are required to handle non-functional concerns. Such concerns can be divided to common features (security, reliability, manageability, etc.) and business specific requirements. Many of the common features are handled by toolkits such as Microsoft Web Services Enhancements, IBM Emerging Technologies Toolkit and Apache Axis.

The two main problems this paper aims to solve is the inability of current toolkits to apply a feature to multiple Web Services in a single process and the fact that current toolkits require developer’s knowledge to apply features to Web Services. As a solution, this paper proposes an Aspect Oriented approach for applying features to Web Services.

The aspect oriented approach presented by this paper should make the process of applying features to Web Services less resource consuming and more flexible than the approach taken by current toolkits.

Virtualised Trusted Computing Platform for Adaptive Security Enforcement of Web Services Interactions

Ivan Djordjevic,Srijith K. Nair,Theo Dimitrakos — 9/29/2007 01:53

Security enforcement framework is an important aspect of any distributed system. With new requirements imposed by SOA-based business models, adaptive security enforcement on the application level becomes even more important.

Our work on the enforcement framework to date has resulted in a comprehensive middleware-based solution leveraging on web services technologies. However, potential merits of hardware-based solutions to further secure application exposure have not been considered so far.

This paper describes a method for combining software resource level security features offered by Web Services technologies, with the hardware-based security mechanisms offered by Trusted Computing Platform and system virtualisation approaches. In particular, we propose trust-based architecture for protecting the enforcement middleware deployed at the policy enforcement endpoints of web and grid services. The main motivation is to additionally secure execution environment of the applications, by providing virtual machine level separation that maps from logical domains imposed by web services level enforcement policies.

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Comparing Web Services Performance and Recovery in the Presence of Faults

Marco Vieira,Nuno Laranjeiro — 9/29/2007 01:55

Web-services are supported by a complex software infrastructure that must ensure high performance and availability to the client applications. Web services industry holds a well established platform for performance benchmarking (e.g., TPC-App and SPEC jAppServer2004 benchmarks). In addition, several studies have been published recently by main vendors focusing web services performance. However, as peak performance evaluation has been the main focus, the characterization of the impact of faults in such systems has been largely disregarded. This paper proposes an approach for the evaluation and comparison of performance and recovery time in web services infrastructures. This approach is based on fault injection and is illustrated through a concrete example of benchmarking three alternative software solutions for web services deployment.

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Deriving Transactional Properties of CompositeWeb Services

Li Li,Chengfei Liu,Junhu Wang — 9/29/2007 01:58

Web services have been emerging as a promising technology for business integration. Transactional support to integrated businesses via composing individual Web services is a critical issue. Current Web services protocols (e.g. BPEL4WS) have been proposed to deal with this issue on a strong assumption that each Web service is compensatable for a recovery purpose. It is arguable that Web services composition requires more transactional support beyond the compensation-based solution. This paper looks into the problem of transactional support for composing and scheduling those Web services that may have different transactional properties. The transactional properties of workflow constructs, which are fundamental to the composition of Web services, are thoroughly investigated. The concept of a connection point is introduced to derive the transactional properties of compositeWeb services. The scheduling issue of composite Web services is also discussed.

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Discovering Conversations in Web Services Using Semantic Correlation Analysis

Wim De Pauw,Robert Hoch,Yi Huang — 9/29/2007 01:59

Composite business applications typically combine characteristics of workflow and transactional applications. In order to handle multiple concurrent sessions and conversations across different nodes and over an extended time period, these applications pass dedicated identifiers inside their messages such as "OrderNumber". Debugging and understanding these conversations and the flow of conversation identifiers can be challenging in realistic business applications.

We present a new heuristic algorithm to find these conversation identifiers and a method to reverse-engineer the conversations from the content of traced messages. Visualizing the results of this analysis provides a deeper understanding of the data flow,

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Automated Testing and Response Analysis ofWeb Services

Evan Martin,Suranjana Basu,Tao Xie — 9/04/2007 02:14

Web services are a popular way of implementing a Service-Oriented Architecture (SOA), which has gained rapid adoption and support from leading companies in in- dustry. Testing can be used to help assure both the cor- rectness and robustness of a web service. Because man- ual testing is tedious, tools are needed to automate test generation and execution for web services. This paper presents a framework and its supporting tool for automat- ically generating and executing web-service requests and analyzing the subsequent request-response pairs. Given a service provider’s Web Service Description Language (WSDL) specification, we first automatically generate nec- essary Java code to implement a client (service requestor). We then leverage automated unit test generation tools for Java to generate unit tests (including extreme, special, and random input values), and execute the generated unit tests, which in turn invoke the service under test. Finally we an- alyze the large number of request-response pairs from the web service invocation and identify robustness problems. We have applied our framework to freely available web ser- vices and our experiences show that we can quickly gen- erate and execute web-service requests that may reveal ro- bustness problems with no knowledge of the underlying web service implementation.

Automatic Assertion of Actor State in Service Oriented Architectures

Ian Wootten,Shrija Rajbhandari,Omer Rana — 9/04/2007 02:12

Documentation of provenance, the process which was taken to create a particular data item, is critical within service oriented architectures where loose coupling between services and clients (actors) is employed. Such a process may involve interaction between multiple services, with each service being managed by a particular actor. The recording of actor state may provide critical contextual information regarding the state of a particular actor at a point during a client-service interaction, but is however typically left undocumented. We discuss the issues that are encountered with the automatic documentation of actor state and the types of resources which may be used to provide it. An architecture which allows monitoring tools to be related to user needs is presented and evaluated against a number of scenarios in a Web Services environment.

A Timed Extension of WSCoL

Luciano Baresi,Domenico Bianculli,Carlo Ghezzi,Sam Guinea,Paola Spoletini — 9/29/2007 02:01

Web service based applications are expected to live in dynamically evolving settings. At run-time, services may undergo changes that could modify their expected behavior. Because of such intrinsic dynamic nature, applications should be designed by adhering to the principles of designby- contract. Run-time monitoring is needed to check that the contract between service providers and service users is fulfilled while the collaboration is in place. We describe a language to specify the expected functional and nonfunctional requirements that a service provider should fulfill. The language (Timed WSCoL) is a temporal extension of a previous proposal (WSCoL). We also illustrate the architecture of a run-time analyzer that checks Timed WSCoL properties. Should such properties be disproved during execution, appropriate recovery and reconfiguration actions may be put in place.

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Visual Analysis of Privacy Risks in Web Services

George Yee — 9/29/2007 02:13

The growth of the Internet has been accompanied by the growth of web services (e.g. e-commerce, ehealth) leading to the need to protect the privacy of web service users. However, before privacy can be protected, it is necessary to understand the risks to privacy that come with the service. Indeed, such understanding is key to protecting privacy throughout the service lifecycle. Unfortunately, there does not appear to be any existing method for privacy risk analysis specifically designed for web services. This paper presents a straightforward method for web services privacy risk analysis that uses visual techniques to improve effectiveness and illustrates the method with an example.

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ReliableWeb Services: Methodology, Experiment and Modeling

Pat. P. W. Chan,Michael R. Lyu,Miroslaw Malek — 9/04/2007 02:19

We identify parameters impacting Web services dependability, describe the methods of dependability enhancement by redundancy in space and redundancy in time, and perform a series of experiments to evaluate the availability of Web services. To increase the availability of Web services, we employ several replication schemes and compare them with a single service. The Web services are coordinated by a replication manager. It provides a round robin algorithm for scheduling the workload of the Web services and keeps updating the availability of each Web service. The replication algorithm and the detailed system configuration are described. Experiments are performed to evaluate the resulting service availability. Modeling on the Web services with Petri-net is constructed and verified through experiments with different applications. With the parameters obtained from the experiments, the proposed model can be engaged to demonstrate the characteristics of the Web service.

Context-Aware Service Composition and Component Change-over using Semantic Web Techniques

Yoji Yamato,Hiroshi Sunaga — 9/29/2007 02:14

This paper shows the effectiveness of dynamic changeover of service components for ubiquitous service composition. Although context-aware services are expected in the forthcoming ubiquitous computing era, conventional service coordination techniques are insufficient because of rigid interface designing. To cope with this problem, we have established a flexible service composition framework, where a semantic-level service scenario is translated and its components are dynamically found, selected, and bound. User situations change with time, so service components should be changed in accordance with context change. We propose a new method that reselects and rebinds service components based on context change. Through a performance measurement, we show the effectiveness and practicality of the new method.

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A Semantic Specification Framework for Analyzing Functional Composability of Autonomous Web Services

Baoping Lin,Qing Li,Naijie Gu — 9/04/2007 02:22

Web services can be described as local autonomous routines communicating with each other through message exchange. Hence a good understanding of the messages defined in each web service is crucial to enabling automatic composition. This paper presents a semantic specification framework for analyzing the functional composability of autonomous web services. As the locally described web services contain both semantics and business protocols, we model the former using ontologies and the latter by finite-state machines. A layered approach is adopted to analyze the web service composability, which shows how to check whether two web services are composable or not. Based on the specification and analysis, a polynomial-time algorithm is devised for checking the composability of web services efficiently.

QoS-aware Service Composition in Service Overlay Networks

Yang Li,JinPeng Huai,Ting Deng,HaiLong Sun,HuiPeng Guo,Zongxia Du — 9/29/2007 02:15

As the amount of web services over the Internet grows continuously, these services can be interconnected to form a service overlay network (SON). On the basis of SON, building value-added services by service composition is an effective method to satisfy the changeable functional and non-functional QoS (Quality of Service) requirements of customers. However, the previous research on QoSaware service composition in SON mainly focuses on the context where services have simple interactions, and it can not support application scenarios with complex business collaboration in electronic business. In this paper, we propose the HOSSON (Hierarchical service cOmpoSition framework in SON) framework, which can be used to construct more general-purpose SON through describing the relations among services using business protocols. In HOSSON, business protocols instead of interactive messages are adopted to simplify the description of service composition requirements and a novel approach named protocol computing are proposed to implement service composition on demand. Furthermore, two algorithms, OSS and MCSS, are designed to support service selection for QoS-aware service composition. Finally, comprehensive simulations are conducted to evaluate the performance of algorithms.

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A Soft Constraints-Based Approach for Reconciliation of Non-Functional Requirements in Web Services-Based Multi-Agent Systems

Andreas Schmid,Srinivas Padmanabhuni,Andreas Schroeder — 9/04/2007 02:27

Over the last years agents have proved to be a powerful mechanism for solving a range of problem sets. In order to fully leverage their power in a multi-agent environment with heterogeneous participants, the establishment of barrier-free communication between different parties is of prime concern. In particular, such an environment may consist of numerous entities, based on different implementations and with different non-functional requirements (NFRs), e.g. encryption key length or latency. Currently, interoperability between the involved parties in multi-agent systems is limited as there is no established way of elaborating a common set of NFRs.

In this paper, we outline a Web services-based architecture addressing this issue of interoperability in multi-agent systems. Furthermore, we introduce a soft constraints-based approach for modeling and reconciling the NFRs. In particular, Web services serve as a tool for establishing an open system providing reliable communication between a variety of agent implementations and possible non-agent based entities while lacking the limitations of Agent Communication Languages (ACLs), which are asynchronous in nature and closed in implementation. In this way, Web services enable the desired level of openness and robustness needed for maximum interoperability. Adding a soft constraints-based approach to the Web services agent layer provides an extensible and flexible mechanism for the reconciliation of interdependent NFRs. We present a prototype implementation of an open, Web services-based framework optimizing unary soft constraints in a pareto optimal way and therefore enabling barrier-free communication in a multi-agent scenario. Due to its open nature, the framework is applicable to any heterogeneous environment in need of reconciling NFRs. To illustrate its functioning, we briefly demonstrate the framework in the potential use case of a Demand Driven Supply Network (DDSN).

Protocol Selection alongside Service Selection and Composition

Jose Ghislain Quenum,Fuyuki Ishikawa,Shinichi Honiden — 9/29/2007 02:16

This paper addresses the issue of coordination mechanism selection in agent based service oriented computing systems. We aim to strengthen the current research on service selection and composition with a dynamic choice of the underlying coordination mechanisms. Indeed, since the environment in such systems might dynamically change, and the agents can have several protocols at their disposal, they need to select the most adequate one for service provision/ request upon the prevailing circumstances. In this paper, we present a joint protocol selection mechanism, which enables agents to decide together the protocols they will use to coordinate each other during a service provision.

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MASC - .NET-Based Middleware for Adaptive Composite Web Services

Abdelkarim Erradi,Vladimir Tosic,Piyush Maheshwari — 9/29/2007 02:21

MASC (Manageable and Adaptive Service Compositions)** is a policy-based middleware for monitoring of Web service compositions and their dynamic adaptation to various runtime changes. MASC policies are described in our new WS-Policy extension called WS-Policy4MASC. Compared with recent related works, MASC has several distinctive characteristics, such as coordination of adaptation on the SOAP messaging layer and the business process orchestration layer, use of both technical and business metrics for adaptation decisions, and extending the power and flexibility of the new Microsoft .NET 3.0 platform. In this paper, we focus on MASC support for adaptation to address business exceptions and manage runtime faults. For example, a sub-process (or an activity) can be added, deleted, replaced, skipped, or retried. We have been implementing a MASC proof-of-concept prototype and evaluating it on adaptation scenarios from a stock trading case study. Our performance studies of the prototype indicate that overheads introduced by MASC are acceptable.

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Guiding the Service Composition Process with Temporal Business Rules

Jun Han,Yan Jin,Zheng Li,Tan Phan,Jian Yu — 9/04/2007 02:31

Service composition has become an important paradigm for building distributed applications and e-business processes. While effort has been reported to verify a posteriori whether a given composition such as a BPEL schema satisfies the predefined behavioural properties, little effort has been made to utilise the properties to assist the designer in developing a correct service composition in the first place. This paper reports our first attempt towards this goal by presenting a framework and associated techniques to provide automated guidance to the designer during the composition design process. The guidance can be suggestions on the next valid steps in the business process, identifications of missing/misplaced steps, and/or propositions for inserting, deleting or reordering activities. The guidance is provided based on the temporal business rules which state the temporal/sequential relationships between business activities.

Flow-Based Service Selection forWeb Service Composition Supporting Multiple QoS Classes

Valeria Cardellini,Emiliano Casalicchio,Vincenzo Grassi,Francesco Lo Presti — 9/29/2007 02:23

In the service oriented paradigm applications are created as a composition of independently developed Web services. Since the same service may be offered by different providers with different non-functional Quality of Service (QoS) attributes, a selection process is needed to identify the constituent services for a given composite service that best meet the users QoS requirements.

In this paper, we consider a broker that offers a composite service with multiple QoS classes to several users each generating a flow of requests over time. We propose a service selection scheme which optimizes the end-to-end aggregated QoS of all incoming flows of requests by means of a simple linear programming problem which scales as the number of users, request volumes and/or services grows. This approach differs from most of the current proposals which may not scale well since: a) requests, even from the same user, are handled independently from one another; and b) the selection process often requires the solution of an NP-hard problem.

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Enhancing BPEL scenarios with Dynamic Relevance-Based Exception Handling

Kareliotis Christos,Vassilakis Costas,Georgiadis Panayiotis — 9/29/2007 02:32

Web services have become the key technology in business processes management. Business processes can be self-contained or be composed from subprocesses; the latter category is typically specified using the Web Services Business Process Execution Language (WS-BPEL) and executed by a Web Services Orchestrator (WSO). During the execution however of such a composite service, a number of faults stemming from the distributed nature of the SOA architecture, e.g. network or server failures may occur. WS-BPEL includes provisions for exception handling, which can be exploited for detecting such failures; once detected, a failure can be resolved by invoking alternate web service implementations that perform the same business task as the failed one. However, the inclusion of such provisions is a tedious assignment for the business process designer, while additional effort would be required to maintain the BPEL scenarios in cases that some alternate WS implementations cease to exist or new ones are introduced. In our research we are developing a framework for automating handling of that kind of exceptions. The proposed solution employs a pre-processor that enhances BPEL scenarios with code that detects failures, discovers alternate WS implementations and invokes them, fully thus resolving the exception. Alternate WS implementation discovery is based on service relevance, which takes into account both functional and qualitative properties of web services.

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A Query-based System for Automatic Invocation of Web Services

9/29/2007 02:34

There is a critical need to design and develop tools that abstract away the fundamental complexity of XML based Web services specifications and toolkits, and provide an elegant, intuitive, simple, and powerful query based invocation system to end users. Web services based tools and standards have been designed to facilitate seamless integration and development for application developers. As a result, current implementations require the end user to have intimate knowledge of Web services and related toolkits, and users often play an informed role in the overall Web services execution process We employ a set of algorithms and optimizations to match user queries with corresponding operations in Web services, invoke the operations with the correct set of parameters, and present the results to the end user. Our system uses the Semantic Web and Ontologies in the process of automating Web services invocation and execution.1

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AutomatedWeb Service Composition at Work: the Amazon/MPS Case Study

Annapaola Marconi,Marco Pistore,Piero Poccianti,Paolo Traverso — 9/04/2007 02:55

Several works address the problem of the automated composition of stateful services, e.g., specified in WS-BPEL. However, the key problem of their practical applicability in real composition scenarios is still open. Addressing this problem requires to provide an easy and affordable way to specify behaviors of component services and composition requirements, as well as composition techniques that are powerful enough to scale to scenarios of realistic size. In this paper we provide a first step towards addressing this problem by evaluating the feasibility and efficiency of a state-of-the art approach to automating the composition task on a real scenario that entails a high level of complexity: the Amazon E-Commerce Services and an e-payment service offered by an important Italian banking Group (Monte dei Paschi di Siena). We show the feasibility of the specification of composition requirements and of the automated generation of complex executable WS-BPEL processes, and analyze the possibility of reducing the effort in the composition task.

CoordinatedWeb Services Orchestration

Geert Monsieur,Monique Snoeck,Wilfried Lemahieu — 9/29/2007 02:36

In a Business Process Execution Language (BPEL) process definition the sequence of exchanged messages typically originates from the sequence of business process activities and from the need of coordination of those activities across the participants of the process. As such business concerns (e.g. the sequence of business process steps) are often mixed with technical aspects (e.g. the sequence of coordination messages). In this article we present an architecture to separate business and technical concerns, which results in a clearer overview of the high-level business process and improves the flexibility and maintainability of the orchestration architecture. The described architecture depends on existing Web service standards. Different eventing and coordination specifications are discussed. The ultimate architecture is mainly based on the WSBrokered Notification and WS-Coordination Framework specifications.

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Improved Adaptation of Web Service Compositions Using Value of Changed Information

Girish Chafle,Prashant Doshi,John Harney,Sumit Mittal,Biplav Srivastava — 9/29/2007 02:37

Workflows often operate in volatile environments in which the component services’ QoS changes frequently. Optimally adapting to these changes becomes an important problem that must be addressed by the Web service composition and execution (WSCE) system being utilized. We adopt the A-WSCE framework that utilizes a three-stage approach for composing and executing Web workflows. The A-WSCE framework offers a way to adapt by defining multiple workflows and switching among them in case of component failure or changes in the QoS parameters. However, the A-WSCE framework suffers from the limitations imposed by a simple strategy of periodically checking the QoS offerings of randomly picked providers in order to decide whether the current workflow is optimal. To address these limitations, we associate the value of changed information (VOC) with each workflow and utilize the VOC to update which workflow to execute. We empirically demonstrate the improved performance of the workflows selected using the new approach in comparison to the original framework.

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Improving the Reuse of ScientificWorkflows and Their By-products

Xiaorong Xiang,Gregory Madey — 9/04/2007 03:13

Most current practical methodologies and workflow systems for service composition and workflow creation in e- Science pursue a semi-automatic way to allow users to discover and select appropriate services to include in a workflow based on semantic and conceptual service definitions. However, few of these approaches consider the potential for reuse: to share the knowledge gained during the service composition process and to reuse complete or partial of existing workflows. We believe that providing a capability for reuse of this knowledge and workflows could be an important component in a workflow system. In this paper1, we present a methodology and an enhanced system design to facilitate the reuse of knowledge and workflows. It contains a hierarchical workflow structure representation, knowledge management and knowledge discovery components to capture and manage the reusable information in a system, and an approach for using a graph matching algorithm to discover similar workflows.

On Completeness of Web Service Compositions

Zhongnan Shen,Jianwen Su — 9/04/2007 03:14

The main objective of composing web services is to identify usable web services through discovery and to orchestrate or assemble selected services according to the goal specification. In this paper, we formulate and study a framework of composing web services through discovery from a given goal service. A general algorithm for composition with or without a goal service invocation request is developed. Two notions of completeness, "schema completeness" and "instance completeness", are defined, which measure the ability of how thoroughly an algorithm can find a composition. The two notions correspond to compositions without or with a goal service request, resp. We show that schema completeness can be achieved by depth-first or breadth-first search combined with a tightening strategy. Further, the breadth-first search avoids redundancy. We also show that while instance complete algorithms exist, they generally need do invoke all candidate services.

PSR : Pre-computing Solutions in RDBMS for FastWeb Services Composition Search

Joonho Kwon,Kyuho Park,Daewook Lee,Sukho Lee — 9/04/2007 03:15

In recent years, the web services composition has received much attention. By web services composition, we mean taking advantage of currently existing web services to provide a new service that does not exist on the repository. In this paper, we propose a new system called PSR for web services composition search using a relational database. We also propose algorithms for pre-computing web services composition using joins and indices. We demonstrated that our pre-computing web services composition approach in RDBMS yields lower execution time and good scalability when handling a large number of web services and user queries.

Integrating Discovery and Automated Composition: from Semantic Requirements to Executable Code

Piergiorgio Bertoli,Joerg Hoffmann,Freddy Lecue,Marco Pistore — 9/04/2007 03:16

Web services are conveniently advertised and published based on (stateless) functional descriptions, while they are usually realized as (stateful) processes. Therefore, the automated enactment of complex web services on the basis of pre-existing ones requires the ability to handle services described at very different abstraction levels. This is the main reason behind the current lack of approaches capable to perform automated end-to-end composition, starting from semantic requirements to obtain executable orchestrations of stateful processes. In this paper we achieve such a challenging goal, by modularly integrating a range of incrementally more complex techniques that cover the necessary discovery and composition phases. By gradually bridging the gap between the high-level requirements and the concrete realization of services, our architecture manages sensibly the complexity of the problem: incrementally more complex techniques are provided with incrementally more focused input. The tests of our architecture on a deployed scenario witness the functionality of the platform and its integrability with standard service engines.

AutomaticWorkflows Composition of Mobile Services

Giuseppe De Giacomo,Massimiliano de Leoni,Massimo Mecella,Fabio Patrizi — 9/29/2007 02:40

Pervasive computing environments are nowadays more and more used as a supporting tool for cooperative workflows, e.g., in emergency management. A typical problem in these scenarios is the synthesis of workflows in presence of sets of services (hosted on mobile devices) with constrained behaviors, just before the collaborating team is dropped off in the operation field.

In this paper, we propose a technique able to automatically synthesize distributed orchestrators, each one coordinating a service and synchronizing with the other orchestrators, given a target generic workflow to be carried out and a set of behaviorally-constrained services.

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An Application of Web-Service Interfaces

Dirk Beyer,Arindam Chakrabarti,Thomas A. Henzinger,Sanjit A. Seshia — 9/29/2007 02:42

We present a case study to illustrate our formalism for the specification and verification of the method-invocation behavior of web-service applications constructed from asynchronously interacting multi-threaded distributed components. Our model is expressive enough to allow the representation of recursion and dynamic thread creation, and yet permits the algorithmic analysis of the following two questions: (1) Does a given service satisfy a safety specification? (2) Can a given service be substituted by a another service in an arbitrary context? Our case study is based on the Amazon.com E-Commerce Services (ECS) platform.

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An Integrated Development Environment for Web Service Composition

9/29/2007 02:44

Web services provide an instantiation of the loosely coupled service–oriented architecture and facilitate the process of enterprise application integration by encapsulating information, software, and other resources. However, to exploit the true potential of web services, it is critical to develop technologies and tools for composing new services from existing ones. While numerous composition approaches have been developed in the past, very little has been done towards tooling. What is clearly lacking is an Integrated Development Environment (IDE) to ease the process of composition, thereby reducing development time and integration efforts. In this paper, we build on our previous work on service composition, and present an IDE for end-to-end composition of web services. We elaborate on the design of the IDE, describe its integration with existing technologies, and discuss its usability based on the findings of a user survey.

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Entrepreneurial View of Automated Process Composition

Thomas Keller,Thomas Marko,Reinhard Riedl — 9/29/2007 02:45

For some, the ultimate goal of the semantic Web Ser-vice initiative is automated interoperation and process composition. Research activity is intense in this field and many approaches have been published and discussed in Academia. However, the predominant view is focused on technical issues, although the business aspects seem to be equally important. The introduction of interoperation and process composition is complex and has a great impact on the enterprise and its value chain network. Hence, industrial scale business cases are missing, a significant drawback that is preventing new technologies from enter-ing the market. A fundamental problem in defining a business case is the lack of a conceptual framework. We need a model of the various factors that influence the enterprise and its value chain network when automated process composition is introduced. This paper presents such a framework, which may be a help in identifing fu-ture business cases and in attracting business partners.

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An Automated Generation of XForms Interfaces for Web Servic

Kisub Song,Kyong-Ho Lee — 9/29/2007 02:46

For users' convenient access to Web services, this paper presents a method for generating XForms based user interfaces from WSDL files. The proposed method uses an XML schema in a WSDL file, and consists of three steps: processing a WSDL file, generating XForms codes, and embedding them into a host language document. Specifically, to generate XForms codes, rules for generating XForms codes, which support complex types and map simple types into appropriate input controls, are proposed. Experimental results with a large volume of WSDL files show that the proposed method generates XForms-based user interfaces from most of WSDL files successfully.

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Raising Programming Abstraction from Objects to Services

Arun Kumar,Anindya Neogi,Sateesh Pragallapati,D. Janaki Ram — 9/29/2007 02:47

Traditional software development involves reusing and building upon off-the-shelf software libraries. This paradigm provides compile time availability of both, component interfaces as well as corresponding implementations. It enables developers to write programs that build on existing functionality without worrying much about the runtime. Service oriented computing presents a different environment that involves actively running components in the form of services. Here, a search step becomes necessary to first discover the component(s) that satisfy the specified requirements. Moreover, services may come up or go down dynamically leading to expiry of searched results which makes dependent programs highly brittle. In this paper, we propose a paradigm shift from objects to services as first class entities. We present service matching techniques defined across design time and runtime. Using these techniques we define language level operations involving services as operands leading to a novel approach for services based software development.

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Improving Web Services Interoperability with Binding Extensions

Enric Jaen Villoldo,Joan Serrat-Fernandez,Emilio Luque — 9/04/2007 03:46

Current web services are able to interoperate successfully with most basic data types. However, due to the limited functionality of existing data binding tools, they still experiment difficulties manipulating more complex XML data types, forcing programmers to work at the XML level. In this paper we propose a business model for web services where data binding tools not only generate the WSDL, but also provide portable binding extensions for manipulating the XSD types. These binding extensions can be integrated into any other binding tool, overcoming their limitations. Because these extensions are written in XML, this model conforms to the principle of platform independence. In addition, this model does not suppose any extra programming effort to neither service providers or clients. The approach has been validated with the creation of several extensions, which has been ported into Java and PHP clients. Our preliminary results show no performance penalty.

Automatic Message Flow Analyses for Web Services Based on WSDL

Li Li,Wu Chou — 9/29/2007 02:50

This paper describes an approach to discover and verify two fundamental relationships in web service message exchange flow patterns, i.e. support and correlate, based on the abstract WSDL specification of the service operations. Compared to methods used in previous studies, this approach is a significant improvement in that flow chain relations can be discovered and identified based on flexible and inexact match of XML Schemas using differential information in plain WSDL and XML Schema files. This approach is also efficient and extensible as it is based on a tree model of schemas and modular node equivalence rules. Pilot experiments on some web services standards, e.g. WS-Session, WSEventing, Parley X, etc., indicated that the proposed method is accurate and effective in identifying the message flow dependencies and related issues in service descriptions. The derived flow pattern relations can be represented as Petri nets that have some practical applications for web service verification, implementation and consumption.

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Modeling the 3-Tier E-Learning System on Power Line Network

Khosro Bahrami,Mehrnoosh Abedi,Behzad Daemi — 9/04/2007 03:57

This paper presents an analytical model of the 3-tiered e-learning system on Power Line Network based on Web Services. Power line communication has high influence and is high speed medium that can be utilized as platform for web based applications such as e-Learning. To achieve this idea, we designed a 3-tiered e-learning system on Power Line Network based on Web Services and SOAP technology. Data tier is a distributed learning object repository to provide learning contents. Business tier is implemented in MV/MV (63kV/20kV) electrical power substations and Presentation tier is implemented in MV/LV (20kV/400V) electrical power substations. In this paper, we present analytical model of 3-tiered e-learning on symmetric and asymmetric Power Line Network based on LMS and LCMS services. For this purpose, we use Network Queuing Model and Mean Value Analysis to predict response time of system. We show that to improve the response time of e-learning, the web and application servers should be selected based on topology and requests of customers to e-learning services.

Evolving Existing Systems to Service-Oriented Architectures: Perspective and Challenges

9/29/2007 02:51

The advent of and growing interest in Service- Oriented Architectures (SOA) present business leaders with a number of problems. They promise to deliver hitherto unseen business process agility, but at the risk of making investment in existing systems obsolete. The established orthodoxy is that the maintenance problem presented by installed systems is about finding an acceptable balance between risk involved in evolving the system and benefits offered by the update. SOAs represent a "paradigm-shift" and, as such, present a more complicatedproblem: how to minimise the risk to their investment (existing software systems) and exploit the benefits of migrating to SOA. We provide a review of a number of approaches that may contribute to a pragmatic strategy for addressing the problem and outline the significant challenges that remain.

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A Service Supporting Universal Access to Mobile Internet with Unit of Information-Based Intelligent Content Adaptation

Stephen J.H. Yang,Jia Zhang,Norman W.Y. Shao,Rick C.S. Chen — 9/29/2007 02:53

In the mobile Internet, users mostly work with handheld devices with limited computing power and small screens. Their access conditions also change more frequently. In this paper, we present a novel service supporting intelligent content adaptation to better suit handheld devices. The underlying technique is a Unit of Information (UOI)-based content adaptation method, which automatically detects semantic relationships among comprising components in Web contents, and then reorganizes page layout to fit handheld devices based on identified UOIs. Experimental results demonstrate that our method enables more exquisite content adaptation.

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Human Interactions in Dynamic Environments through Mobile Web Services

Daniel Schall,Robert Gombotz,Christoph Dorn,Schahram Dustdar — 9/29/2007 02:53

In this paper we present the concept of Activity- Centric Collaboration Using Service-Oriented Architectures (ACCUSO), which addresses the requirements arising from ad-hoc collaboration in mobile teams. In ACCUSO, activities are used to map human actions to Web Services exploiting the potential benefits of SOA, such as service discovery and binding at runtime. The possibility to compose activities hierarchically from sub-activities and to redesign running activities provides the process-flexibility required in ad-hoc collaboration. We expand the notion of service orientation by introducing Human-provided Services (HpS) which provide functionality not realizable through software services. HpS are "implemented" by human actors (possibly being mobile), which remains transparent to the system, thereby allowing for the provisioning of HpS based on conventional WSinfrastructure. The feasibility and applicability of ACCUSO is demonstrated through a proof-of-concept implementation.

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Modeling and Generating Mobile Business Processes

Lasse Pajunen,Anna Ruokonen — 9/29/2007 02:57

A mobile business process is a special case of a business process where most of the human interaction is done using mobile devices. In this paper, we propose UML-based sup- port for developing such mobile business processes. Here, the business process is first modeled using UML. Then the process model is translated into a BPEL description, which can be run in mobile and/or network-based workflow en- gines. We propose rules to guide modeling of mobile busi- ness processes, to import existing WSDL decriptions into UML models, and to generate executable BPEL descrip- tions with appropriate WSDL definitions. In addition, we introduce our implementation of the approach. The practi- cal applicability is demonstrated by designing a group mes- saging process. It provides a customizable mobile device based communication service offering a business case for mobile operators.

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WS-CDL+: An Extended WS-CDL Execution Engine for Web Service Collaboration

Zuling Kang,Hongbing Wang,Patrick C.K. Hung — 9/29/2007 02:58

Web services are becoming the prominent paradigm for distributing, computing, and electronic business, while there is an increasing surge to provide online Businessto- Business collaborations. The Web Services Choreography Description Language (WS-CDL) is a Web service specification developed by W3C, in order to provide peer-to-peer collaborations for participants from different parties. Despite the great research interests it has received during recent years, no practical or even prototype execution engine has been built for WS-CDL, which is, however, essential to test and evaluate the properties of WS-CDL when doing research on it, and promote its application fields in business. This paper implements an execution engine of WS-CDL, which has never been built before, and experiments on the functionalities and performance of the engine. We also address the extensions toward WS-CDL, namely WSCDL+, which are built into our execution engine. Finally, the whole paper is concluded, addressing the application perspectives of WS-CDL/WS-CDL+.

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Context Aware Service Policy Orchestration

Yu Chen Zhou,Xin Peng Liu,Eduardo Kahan,Xi Ning Wang,Liang Xue,Ke Xin Zhou — 9/04/2007 04:09

While service oriented computing is gaining popularity and design methodology for functional features is becoming mature, design of non-functional features and governance capabilities is increasingly important. WS-Policy has been touted as a standard way to specify service policy for these features and map service policy to upper layers of SOA policy model for SOA governance. This paper introduces a novel model-driven method to orchestrate service policy within system context in design time. By applying top-down SOA design methodology, firstly the logical service policy model is created to describe relation among service policy in logical level, and then it is transformed to physical service policy model with more factors of real system topology considered. Finally, service policy deployment model is generated to describe the relation among policy related artifacts and policy repositories, and guide and automate the deployment of policies in runtime environment as well. Leveraging system topology and behavior information, service policies are orchestrated vertically and horizontally according to service policy dependency, business policy, Service Level Agreement (SLA), and domain specific constraints. Meta-policy based service policy conflict detection and resolution is highlighted. We demonstrate how this approach significantly enhances the capability to ensure the correctness and consistency of service policy within service oriented computing environment.

Service-Oriented Virtual Private Networks for Grid Applications

9/29/2007 03:04

Emerging Grid applications desire not only high bandwidth but also the ability to control the topology and traffic engineering of the underlying networks, through web service interfaces. To achieve that goal, we present an advanced User Controlled Lightpath Provisioning (UCLP) system, where network resources and Grid resources are both modeled as web services and are seamlessly integrated into workflows.

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Practical DACSWeb Service for User’s Free Portal Page Creation

Kazuya Odagiri,Rihito Yaegashi,Masaharu Tadauchi,Naohiro Ishii — 9/04/2007 04:12

As a communication mean, Personal Portal which is an entrance where each user can acquire his/her interested information on the network, is often used. We have problems on the existing Personal Portal described as follows. First, the program to realize the Personal Portal which is located on a specific Web Server, becomes large-scaled and complicated. Because Web pages as Personal Portal depend on that program, those Web pages can’t always be useful for each user equally. Therefore, to solve these problems, we developed two kinds of new Web Service which are realized on the network introducing DACS(Destination Addressing Control System) Scheme, which is the network management scheme by communication control of client computers. By use of these Web Services, each user can create the customized Personal Portal, which displays the information by a user unit, for using in actual network easily and freely for oneself. In this paper, to deal with information not only by a user unit, but also by a group unit and by all users unit, DACS Web Service is proposed. DACS Web Service is realized by extending two kinds of functions of Web Service respectively and integrating these functions. As the result, each user can create the customized Web page as Personal Portal, which will be often useful in actual network.

Stochastic Modeling Study for Competitive Web Services Market

Shuxing Cheng,Carl K.Chang,Liang-Jie Zhang — 9/29/2007 03:11

In our earlier work, competitive Web Services market was proposed to address one of the major business concerns, namely "competitiveness", of the current Web services research. This paper aims to attack the issues of how to model and analyze competitive Web services Market, which ranges from the service node at the micro level to the competitive composite service providers at the macro level. Moreover, in order to tackle and contain the randomness embedded in a Web services system, we apply the Markov chain theory to analyze the availability of Web services Market. Moreover, we analyze the stochastic performance of the Web services market using queuing theory and propose the adaptive control methodology to improve the performance.

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Service HyperChain Architecture of Web X.o and A Case Study

Liang-Jie Zhang,Hong Cai — 9/29/2007 03:12

The word "Web X.o" represents "Web eXpandoo" which is derived from "Web" and a misspelled word "Expandnoon". "noon" is interpreted as "the highest, brightest, or finest point or part" or "the highest point". This paper introduces some basic features of Web X.o that expands the current Web to the "highest and brightest" point. The key concept of Services HyperChain in the Web eXpandoo framework is introduced to provide an enabling technology architecture that supports the future Web, which coordinates multimedia presentations, human interactions, business processes, computing resources, and business applications in a uniform fashion. Today’s Web 2.0 technologies are mainly dealing with the presentation and community-based interaction aspects in the Web X.o framework. The boundary among Web, desktop applications, and backend resources are removed by creating Services HyperChain in the Web eXpandoo framework. The IEEE Body of Knowledge on Services Computing system is used as a prototype to illustrate how the Service-Oriented Architecture (SOA) and Web 2.0 technologies are used to to realize the Services HyperChain with unified services resource and services ecosystem enablement architecture of Web X.o.

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Data-Grey-BoxWeb Services in Data-Centric Environments

9/29/2007 03:13

In data-centric environments, for example, in the field of scientific computing, the transmission of large amount of structured data to Web services is required. In serviceoriented environments (SOA), the Simple Object Access Protocol (SOAP) is commonly used as the main transport protocol. However, the resulting ’by value’ data transmission approach is not efficiently applicable in data-centric environments. One challenging bottleneck of SOAP arises from the XML serialization and deserialization when processing large SOAP messages. In this paper, we present an extended Web service framework which explicitly considers the data aspects of functional Web services. Aside from the possibility to integrate specialized data transfer methods in SOA, this framework allows the efficient and scalable data handling and processing within Web services. In this case, we combine the advantages of the functional perspective (SOA) and the data perspective to efficiently support data-centric environments.

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A Service Oriented HLA RTI on the Grid

Ke Pan,Stephen John Turner,Wentong Cai,Zengxiang Li — 9/29/2007 03:15

Modeling and simulation permeate all areas of business, science and engineering. To promote the interoperability and reusability of simulation applications and link geographically dispersed simulation components, distributed simulation was introduced. While the High Level Architecture (HLA) is the IEEE standard for distributed simulation, a Run Time Infrastructure (RTI) provides the actual implementation of the HLA.With increased size and complexity of simulation applications, large amounts of distributed computational and data resources are required. The Grid provides a flexible, secure and coordinated resource sharing environment which can facilitate distributed simulation execution. In this paper, we propose a Service Oriented HLA RTI (SOHR) framework which provides the functionalities of an RTI as Grid services and enables large scale distributed simulations to be conducted on a heterogeneous Grid environment. The various services in SOHR can be dynamically deployed, discovered and undeployed, leading to a scalable distributed simulation environment. While the communications between simulators are through Grid service invocations, the standard HLA interface is provided as a library to increase simulator reusability and interoperability. A subset of HLA specifications was implemented in a SOHR prototype based on GT4 and the experimental results have verified the feasibility of SOHR.

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Towards a Fine-Grained Access Control Model and Mechanisms for Semantic Databases

9/29/2007 03:24

A growing number of domains are adopting semantic models as a centralized gateway to heterogeneous data sources, or directly for modeling and managing relevant information. In such contexts, it is crucial to grant access to the semantic model and its data only to the authorized users. In this paper, we present a fine-grained access control model specifically tailored to semantic models. One of the relevant features of the model is the granularity of the resources that can be protected. Access control can be enforced at the level of both the model’s concepts and the concepts’ instances by means of a query rewriting strategy. The proposed model has been implemented adopting the XACML standard and the SeRQL query language; services exposed by the implementation can be used to transparetly integrate authorization into existing systems.

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XML Document Retrieval System Supporting Multimedia Web Service for Digital Museum

Jae-Woo Chang,Young-jin Kim — 9/04/2007 04:20

In this paper, we develop an XML document retrieval system supporting a multimedia Web service for a digital museum. It can support unified retrieval on XML documents based on both document structure and image content. To achieve it, we perform the indexing of XML documents describing Korean porcelains used for a digital museum, based on not only their basic unit of element but also their image color and shape features. In addition, we provide a similarity measure for a unified retrieval to a composite query, based on both document structure and image content. Finally, we implement our XML document retrieval system designed for a digital museum Web service and analyze its performance in terms of retrieval time, insertion time, storage overhead, as well as recall and precision measure.

Developing a Distributed e-Monitoring System for Enterprise Website and Web Services: An Experience Report with Free Libraries and Tools

Frank K.W. Cheong,Dickson K.W. Chiu,S.C. Cheung,Patrick C. K. Hung — 9/29/2007 03:26

Enterprises value monitoring as it provides dependable e-services, whether it is an interactive web site or programmatic Web service. However, this task becomes non-trivial when enterprises begin to require support from thousands of servers across geographical areas. How can the communications between a monitoring systems and remote servers be minimized? Could the task be achieved easily based on a readily available technology such as SNMP? How can we monitor thousands of servers powered by, say, Tomcat, which lacks SNMP support? How may a poorly responsive site be identified prior to being reported as a failure by SNMP? In this paper, we propose a unified e-monitoring system that enables system administrators to remotely monitor the health of distributed e-services in both the form of website and Web services. We further discuss our implementation experience based on a pragmatic prototype.

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DIA: A Web Services-based Infrastructure for Semantic Integration in Geoinformatics

Zaki Malik,Abdelmounaam Rezgui,A. Krishna Sinha,Kai Lin,Athman Bouguettaya — 9/29/2007 03:27

We present DIA, a Web services-based infrastructure for the Discovery, Integration, and Analysis of geoscience data, tools, and services. DIA provides a collaborative environment where scientists can share their resources (e.g., geochemical data, filtering services, etc.) by registering them through well-defined ontologies. We have developed a planetary materials ontology in OWL for this purpose. The ontology is used by different geoscientists (using Web services) to explore, extract, and integrate information from different heterogeneous data sets. The DIA system is now in its final pre-release phase. It is currently made accessible to a few geoscientists for conducting usability analyses, and it will eventually be made available to the community at large through the geoscience portal (GEON) at the San Diego Supercomputer Center.

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Transactional Coordination of Dynamic Processes in Service-Oriented Environments

Martin Husemann,Michael von Riegen,Norbert Ritter — 9/29/2007 03:28

Service-oriented environments facilitate dynamic processes whose properties can be altered during runtime. The transactional support of such processes holds specific requirements that are not completely covered by existing specifications. In this paper, we introduce a life cycle model for transactional dynamic processes and analyze existing specifications with respect to their potentials to support such a model. Subsequently, we propose a framework resolving the weaknesses of existing specifications and allowing comprehensive transactional coordination of dynamic processes.

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Towards automatic mediation of OWL-S process models

Roman Vaculín,Katia Sycara — 9/29/2007 03:33

The framework for automatic mediation of two process models composed of semantically annotated web services is presented. Process mediation is hard because of many possible mismatches between process models. We introduce algorithms for the process models analysis to find possible mappings between provider’s and requester’s process models, or to identify incompatibilities that cannot be reconciled with given set of available data mediators and external services. Results of the analysis phase are used in the mediator runtime component. In particular, we show how the workflow and dataflow mismatches can be resolved.

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Efficient Service Data Management in Dynamic Environment

Xiaoling Wang,Aoying Zhou,Guimei Liu — 9/04/2007 04:29

With the increasing service-oriented applications, efficient service data management is becoming a practical and important issue. Currently, most exchange messages among different web services is SOAP, which is represented by XML-formatted data. So, the main task of service data management is to manage XML format message files in order to provide efficient store and query for service requestors. Storing XML documents in relational databases has drawn much attention in recent years because it can leverage existing investments in relational database technologies. However, most former work defines relational schema for XML files based on heuristics without considering application characteristics, hence fails to produce efficient relational schema for various applications. In this paper, we propose an autonomic, workload-aware approach to generate relational schema according to dynamic application characteristics or user specified workload. Our approach adopts the genetic algorithm to find optimal mappings, and an elegant encoding method and related operations are proposed to manipulate mappings using bit strings. We implemented the proposed algorithm and our preliminary experiment results showed that our algorithm was more robust, more suitable for dynamic SOA applications and produced better relational schema than existing work.

Privacy-Aware Web Service Protocol Replaceability

Nawal Guermouche,Salima Benbernou,Emmanuel Coquery,Mohand-Said Hacid — 9/29/2007 02:06

Business protocols are becoming a necessary part ofWeb services description [4]. The work presented in [4] investigates mechanisms for analyzing the compatibility and the substitution (i.e., replaceability) of Web services based on their functional properties. In this paper, we focus on the replaceability analysis.Whether a service can replace another depends not only on their functional properties but also on non functional requirements (e.g., privacy policies). We propose a privacy-aware protocol replaceability approach to extend the work presented in [4] by privacy properties. We introduce a rule-based privacy model and we extend business protocols, leading to what we call private business protocols. Finally, a private replaceability analysis of private business protocols is discussed. We mainly investigate compatibility issues, that is whether one private business protocol can support the same set of conversations with respect to the privacy requirements.

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A Situation-aware Access Control based Privacy-Preserving Service Matchmaking Approach for Service-Oriented Architecture

Stephen S. Yau,Junwei Liu — 9/29/2007 03:36

Service matchmaking is an important process in the operation of Service-Oriented Architecture (SOA) based systems. In this process, information from both service providers and requestors are used. How to protect the privacy of participating parties during the matchmaking process imposes a challenge. In this paper, a privacypreserving service matchmaking approach is presented to support semantic-based service matchmaking and avoid privacy leakages to untrusted parties. The approach uses situation-aware access control (SA-AC) mechanism to ensure the appropriate disclosure and use of private information by modeling, specifying and enforcing SA-AC policies. It provides an owner-centric mechanism for both service providers and requestors in SOA-based systems to protect their private information during service matchmaking. Keyword: Service-oriented architecture, SOA-based systems, service matchmaking, privacy-preserving, situationaware access control.

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Access Control for Collaborative Systems: A Web Services Based Approach

Anas Abou El Kalam,Yves Deswarte,Amine Baïna,Mohamed Kaaniche — 9/04/2007 04:32

Nowadays, systems are more and more open, distributed and collaborative. In this context, access control is an important issue that should be studied, specified and well enforced. This work proposes a new access control model for collaborative systems: "PolyOrBAC". On the one hand, we extend OrBAC (Organization-Based Access Control Model) to specify local as well as collaboration access control rules; on the other hand, we enforce these security policies by applying web services mechanisms (XML, SOAP, UDDI and WSDL). Then, we present a representative scenario of secure collaborative applications. Furthermore, we propose a XACML-based implementation of PolyOrBAC and we discuss the most important approaches that emphasize access control in collaborative environments.

Managing Top-down Changes in Service-Oriented Enterprises

Xumin Liu,Athman Bouguettaya — 9/29/2007 03:40

A Service Oriented Enterprise (SOE) provides an efficient and flexible platform where multiple Web services can cooperate together to provide a value-added service. Change management is one of the fundamental issues in enabling SOEs. In this paper, we propose a framework that facilitates in automatically managing top-down changes in SOEs. We start with formalizing a SOE’s schema since it is a central concept for specifying and managing top-down changes in SOEs. We then propose a change model as a guide to react to changes. Algorithms are proposed to implement changes by refining a SOE’s behavior.

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Designing a Generic Collaborative Working Environment

M. A. Martínez-Carreras,A. Ruiz-Martínez,F. Gómez-Skarmeta,W. Prinz — 9/04/2007 04:36

Groupware provides an essential support for the maintenance of Knowledge Management in many organizations. Accordingly, the use of groupware systems has become widespread. However, still some problems regarding the way in which business process are implemented exist, because they require the communication between several of these groupware systems to fulfill all required objectives in the organization. For that reason, interoperability issues have taken a vital role in the business sector. In this area, one of the leading technologies is the Web Service standard.. In this paper we describe the design of a Generic Collaborative Working Environment to provide the basis for allowing interoperability with several groupware systems. We also reflect how Web Services technologies are used in the design of this environment.

Supporting Differentiated ServicesWith Configurable Business Processes

Aries Tao Tao,Jian Yang — 9/29/2007 03:48

Service Oriented Computing (SOC) allows resources on a network to be made available as services. For a business service, differentiated services can be provided based on the usage context, i.e., location, age, purpose and user profiles. In differentiated services, service outcomes depend on context. Currently there is no efficient technical solution for supporting differentiated service development. In this paper we present an approach to deliver differentiated services realized by configurable business processes so that service flexibility, manageability and reusability can be achieved.

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A Web Service Mining Framework

George Zheng,Athman Bouguettaya — 9/04/2007 04:37

We propose a service mining framework for exploring interesting compositions of existing Web services. The framework first screens Web services for composition leads using a "coarse-grained" filtering approach. It then verifies these leads based on runtime conditions. Top candidates are selected from the verified leads and evaluated for their interestingness. We present algorithms to automate the screening phase of the framework. Finally, we study the effects of key variables on lead compositions’ interestingness. As a motivating example, we apply these algorithms to the field of biological pathway discovery and rely on knowledge obtained from reverse engineering online resources to assess their effectiveness.

WSCE: A Crawler Engine for Large-Scale Discovery of Web Services

Eyhab Al-Masri,Qusay H. Mahmoud — 9/04/2007 04:38

This paper addresses issues relating to the efficient access and discovery of Web services across multiple UDDI Business Registries (UBRs). The ability to explore Web services across multiple UBRs is becoming a challenge particularly as size and magnitude of these registries increase. As Web services proliferate, finding an appropriate Web service across one or more service registries using existing registry APIs (i.e. UDDI APIs) raises a number of concerns such as performance, efficiency, end-to-end reliability, and most importantly quality of returned results. Clients do not have to endlessly search accessible UBRs for finding appropriate Web services particularly when operating via mobile devices. Finding relevant Web services should be time effective and highly productive. In an attempt to enhance the efficiency of searching for businesses and Web services across multiple UBRs, we propose a novel exploration engine, the Web Service Crawler Engine (WSCE). WSCE is capable of crawling multiple UBRs, and enables for the establishment of a centralized Web services’ repository which can be used for large-scale discovery of Web services. The paper presents experimental validation, results, and analysis of the presented ideas.

Enabling Runtime Adaptation ofWorkflows to External Events in Enterprise Environments

Dipanjan Chakraborty,Vinod V. Mankar,Amit A. Nanavati — 9/04/2007 04:43

This paper presents the design and implementation of Heterogeneous Event Management Middleware (HEMM) that integrates events across multiple siloed workflow management systems (WFMS) in enterprises. Specifically, we address the issue where a high-level change (e.g. change in business policy or rolling out of a new service) necessitates external events (generated from other enterprise system) to be handled by running workflow (WF) instances in the WFMS. Current solutions either require a change in the workflow process deflnition or change in the workflow engine - both being cost intensive solutions from an enterprise's point of view since they compromise on enterprise backend downtime. HEMM circumvents this by introducing an overlay on top of existing WFMS and abstracting out unforeseen event handling from workflows. At the same time, it employs event transformation to map events to appropriate event handlers of running workflow instances, enabling them to adapt to new events that their process definitions do not handle. We demonstrate our prototype implementation with the example of rolling out a bundled service that is prevalent in telecom industry.

On Demand Network and Application Provisioning ThroughWeb Services

Sandy Liu,Yong Liang,Bo Xu,Libo Zhang,Bruce Spencer,Martin Brooks — 9/04/2007 04:45

While most service-oriented solutions are developed for system integration or data integration, we propose a Web Services-based solution, Eucalyptus, for provisioning applications and networks on demand. Eucalyptus is built on the power of the User-Controlled Lightpath Provisioning (UCLP) tool, which pioneers a user-centric and serviceoriented approach for creating and managing a private endto- end optical network. As a first user of UCLP, Eucalyptus aims to construct an participatory environment for geographically distributed teams of architects and industrial designers with the with the support of configurable broadband switched networks, as well as the traditional routed IP networks.

The contribution of Eucalyptus is to provide a proof-ofconcept example on how Web Service and Service-oriented Architecture (SoA) can effectively provide on-demand provisioning for heterogenous resources in hybrid networks. These resources can be provisioned, launched, monitored, terminated, and reserved through Web Services. Eucalyptus is network and platform neutral. It offers a single point of entry for users to access resources ranging from video conference applications, rendering clusters, to the underlying networks. Each resource is configured through a resourcespecific Web Service. Eucalyptus also includes a set of generic management Web Services to coordinate sessions, to manage resources and users, and to compose workflows, such that the network and the application are properly configured for the users engaging in a participatory design session.

Performance Evaluations of Geospatial Web Services Composition and Invocation

Jianting Zhang,Deana D. Pennington,William K. Michener — 9/29/2007 03:54

Geospatial data and analytical functions are essential to geospatial modeling. There are increasing interests in publishing both geospatial data and analytical functions as Web services and use them as the building blocks for domain specific geospatial modeling. While the advantages of using the Web Services technologies have been well recognized and a number of prototype systems have been built to demonstrate the feasibility, very few performance evaluations have been reported in the previous studies. Compared with business data, geospatial data is rich in data types, large in data volumes and complex in semantics. On the other hand, the Web Services technologies are known to have significant overheads with respects to deployment and invocation. The answers to how effective the Web Services technologies can be, and, to what extent they are effective under the typical computation environments for geospatial modeling remain largely unknown.

In this study we have set up an experimental system by deploying several geospatial Web services on top of popular commercial and open source spatial databases and Geographical Information Systems (GIS). The Kepler scientific workflow system is used for geospatial Web services composition and invocation. We have conducted experiments to chain the geospatial Web services into a geospatial model under two data volume levels and two network settings. Our experiments show that the geospatial modeling using the Web Services technologies remains effective in the wired LAN computation environment for data volume as large as 10000 points. However, the same data volume level incurs significant response lags under the wireless WAN computation environment. The experimental results may be used as a guideline for geospatial modeling using the Web Services technologies when performances need to be taken into considerations.

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Asynchronously Rendering Interoperable Remote Portlets

Hao Zhang,Shun Jiang,Chunhua Tian,Rongzeng Cao,Wei Ding — 9/29/2007 03:54

Under current synchronous portal rendering mechanism, a user has to wait until all the portlets are ready for the next interaction. In the case of consuming remote portlets with Web Services for Remote Portlets (WSRP) specification, the situation can be worse. To improve user experiences, an asynchronous mechanism is proposed in this paper leveraging popular Ajax technology. We also discussed several issues such as URL rewriting, cross-portlet interaction, security, etc. that have to be considered while applying asynchronous mechanism, and built up a prototype to prove that using Ajax in rendering remote portlets while providing cross-portlet interaction capability is feasible.

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Towards Response Time Estimation in Web Services

Francesco Lelli,Gaetano Maron,Salvatore Orlando — 9/29/2007 03:55

Monitor and control operations demand deep interaction between users and devices, while they require the adoption of high interoperable solutions that only SOA-based Web Services can offer. When the access is performed via Internet using Web Services calls, the remote invocation time becomes crucial in order to understand if a service can be controlled properly, or the delays introduced by the wire and the serialization/deserialization process are unacceptable. We propose methodologies, based on a 2k factorial analysis and a Gaussian Majorization of previous service execution times, which enable the estimation of a generic remote method execution time.

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Model Checking Expressive Web Service Descriptions

Sudhir Agarwal — 9/29/2007 04:02

In order to find suitable web services in a large mar- ket of web services, automatic support is needed to fil- ter out web services semantically. Existing matchmaking approaches mainly consider only the types of the input and output parameters, which is not sufficient in prac- tical scenarios. In this paper, we present formalisms for modeling functional and non-functional properties ofweb services and for specifying user goals. We show how ex- pressive web service descriptions can be checked for sat- isfiability of the user goal.

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Concurrency Issues in Automating RTS for Web Services

Michael Ruth,Shengru Tu — 9/29/2007 04:03

Regression testing (RT), testing software with previously used test cases, is a mainstream practice in software maintenance. Regression test selection (RTS) is to reduce the number of tests which need to be retested. Safe RTS techniques add the assurance that no modification-revealing test case will be left unselected. Several effective safe RTS techniques were developed for traditional applications, but none of them can be directly applied to Web services, even though there have been RT tools and techniques for Web services test-case generation, and ranking competing services.

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Using Scenario Oriented Response-time Management for Composite Web Services

WANG Ya-sha,ZHAO Jun-feng,LI Ge — 9/29/2007 04:32

In order to make a composite web service meet user’s response-time requirement, the proper instance of each member web service should be selected and bound. In the literature, all the member web services of a composite web service are treated equally during the response-time management, but without considering their different capabilities of effecting the user’s satisfaction. However, in a certain using scenario, some member services are more sensitive than others, that is to say, in a given composite web service, if these sensitive services delayed, the decline of users’ satisfaction is remarkably greater than that when other services delayed. In this article, a using scenario oriented response-time management method is proposed to reduce the delaying risk of the time sensitive web services, and thus to improve the user’s satisfaction of a composite web service. Our experiments validated the efficiency of the proposed method.

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Dependency-aware Service Oriented Architecture and Service Composition

Jiehan Zhou,Daniel Pakkala,Juho Perala,Eila Niemela — 9/29/2007 04:39

Current service-oriented architecture (SOA) focuses on service composition for application development, i.e. application composition, which is perceived as volatile (i.e. “compose one time and use one time.”). This paper focuses on service composition information (i.e. service dependency) management and dependency-aware service composition for service development (i.e. service composition). This paper explores service composition and service dependency by proposing an extended SOA model, including: 1) establishing a dependency-aware service-oriented architecture (DSOA) that specifies dependency-aware service interactions, i.e. service publication, discovery, composition and binding; 2) developing an upper service dependency ontology for non-volatile DSOA service composition; and 3) demonstrating the validation of DSOA service composition by implementing a DSOA service manager.

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Session Management for Cross-protocol Identity Federation

Hidehito Gomi — 9/29/2007 05:11

Identity management is a key technology to enable federation of web services for authorized users. It mainly focuses on exchanging identity related information properly among web based systems. However, little attention has been given to multimedia services. We propose a design and architecture of a federating proxy that relays user’s authentication and session related information to existing systems that employ different communication protocols. It provides a framework for bridging gap in the schema and syntax of the protocols while it reuses deployed infrastructure.

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Behavioral Queries for Service Selection: An Agile Approach to SOC

Rosa Laura Zavala Gutierrez,Benito Mendoza,Michael N. Huhns — 9/29/2007 05:25

Automatic service discovery and selection is the key aspect for composing Web services dynamically in service-oriented computing (SOC). Current approaches to automating discovery and selection make use of only structural and functional aspects of the Web services. We believe that behavioral selection of Web services should be used to provide more precise results. Service behavior is difficult to specify prior to service execution and instead is better described based on experience with the service execution. In this paper, we propose a novel approach to service selection and maintenance-inspired by agile software development techniques-that is based on behavioral queries specified as test cases. Behavior is evaluated through the analysis of execution values of functional and non-functional parameters.

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A Graph-BasedWeb Service Composition Technique Using Ontological Information

Reyhan Aydogan,Hande Zirtiloglu — 9/04/2007 05:05

We investigate Web service composition as a planning problem and use the input-output parameter relations in order to select the constituent services that make up the composite service. Furthermore, we make use of ontological information between the input-output parameters such that a more specific concept can be used instead of a general concept to make the process more flexible. Our proposed approach is based on constructing a dependency graph including the service parameters and Web services themselves. By using this dependency graph, we perform backward chaining starting to search from the desired output parameters, which is in fact the goal, to the available input parameters. In addition to using semantic information through the search, our approach considers non-functional attributes of the services such as service quality. Considering the quality measures, we find the constituent services by making use of depth first search. After finding the required services, our algorithm generates a plan that shows the execution order of each service.

A Framework for Smooth Composition of Choreographies of Web Services

Juddy A. Gomez-Gutiérrez,Pedro I. Rivera-Vega — 9/29/2007 05:32

The composition of web-based services is a process that usually requires advanced programming skills and vast knowledge about specific technologies. One such modern technology is web services. In this work, we propose a framework for the smooth composition of web services that are targeted to provide particular government services that usually require interaction between several agencies. The goal is to allow government agencies to smoothly register simple services or create new ones based on other already registered simple or composed services. Our work has the additional goal of reducing the overhead involved in the execution of composite services by providing efficient mapping schemes to bypass intermediary composed services and allowing direct invocation of the basic services in the composition.

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A Feedback Control Framework of Service Composition Execution for Response Time Guarantee

Chunming Gao,Weian Chen,Huowang Chen — 9/04/2007 05:08

The Service Composition Execution Engine- WebJetFlow with dual feedback control loops, which separates Process Executor and Service Proxy to decouple process execution and service invocation, is designed and implemented. The experiment results show that the feedback control mechanism enables WebJetFlow to provide response time guarantee for differentiated processes even when workload varies significantly, and the decoupling method increases the throughput of WebJetFlow.

Efficient Web Services Composition and Optimization Techniques

Kwangcheol Shin,SangYong Han — 9/04/2007 05:09

In this paper, we suggest a simple but efficient solution for the Web service composition. When we search Web services for composition, we visit the service which gives the biggest number of new responses, because then there is a higher probability to invoke more other Web services. And also we suggest optimization techniques to get optimized composition result. Optimization processes consist of two phases: one is to remove unnecessary Web services and the other is to find the best starting point of a composition. Test results show that the proposed composing and optimization methods can compose Web services in optimal length in fast way.

Automatic Web Service Composition Based on Logical Inference of Horn Clauses in Petri Net Models

Xianfei Tang,Changjun Jiang,Zhijun Ding — 9/04/2007 05:18

This paper introduces an automatic Web service composition method based on logical inference of Horn clauses in Petri net models. The available services and user request described in SAWSDL are translated into a set of Horn clauses and the composability rules of the services’ input/output parameters are established using ontology reasoning. We choose Petri net as the model of this set of Horn clauses. T-invariant method of Petri nets is used to determine the existence of composite Web services that can fulfill user’s requirement.

OWL-T: A Task Ontology Language for Automatic Service Composition

Vuong Xuan TRAN,Hidekazu TSUJI — 9/04/2007 05:19

In order to satisfy incremental business demands, it is often required to combine functionalities of several services together. A number of approaches for service composition have been therefore proposed in both academic and industrial communities. These approaches, such as BPEL, WSCI, etc. can be categorized into static, manual service composition methods. In addition, by applying Semantic Web technologies, many research works have been investigated to support automatic service composition. Despite of the significant results being achieved, the task of service composition is still a challenging and complex issue. The main reason is that the former approaches require too much detail and technical interventions for defining business processes while the latter approaches are not much scalable for sophisticated applications. In this paper, we will introduce our approach for developing an ontology/language based on the OWL, called OWL-T (T stands for task), which can be used for users describing and specifying formally and semantically their needs at a high-level abstraction, which can be then transformed into executable business processes by underlying systems. The OWL-T aims at facilitating the modeling of complex demands or systems without regarding details of low-level and technical aspects of underlying infrastructure.

A Pragmatic Methodology to Web Service Discovery

Electra Tamani,Paraskevas Evripidou — 9/29/2007 05:36

As in linguistics the semantics co-exist with pragmatics to provide complete and unambiguous meaning to utterances, in the same way the pragmatics should augment the semantics in intelligent applications. Service-Oriented computing is an area where such intelligent applications are greatly facilitated. In this paper we propose a pragmatic methodology to web service discovery which utilizes both the pragmatics and the semantics. This methodology aims to solve a very basic problem of existing semantic discovery approaches: the inability of selecting the most appropriate service among many semantically equivalent web services.

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Search Algorithms for Discovery of Web Services

Janette Hicks,Madhusudhan Govindaraju,Weiyi Meng — 9/29/2007 05:37

Web services are designed to standardize interactions between heterogeneous applications using Internet technologies. Within the framework of Internet search technologies, Web services provide structured channels to access search engines and web-accessible databases. Our work involves research in methods to discover Web Service Description Language (WSDL) documents, which provide interface formats, expected data-types, supported protocols and precise service endpoints. This project extends current discovery research through use of the Google Web service, UDDI category searching, and private registry querying with preliminary experiments resulting in a very high percentage of success. The goal is to find WSDL documents for a given domain name, parse the desired service document to obtain invocation formats, and automatically invoke the Web service. Contributions of this research will support enhancements of HTML-dependent search tools by providing access to data inaccessible through surface HTML interfaces.

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Design and Implementation of an Extended UDDI Registration Center for Web Service Graph

Jianxun Liu,Jie Liu,Lian Chao — 9/04/2007 05:22

UDDI registration center provides a set of management mechanism for Web services providers to publish their Web service and for Web service consumers to inquire what they needs. It solves the problem of Web service description, discovery and Integration. Web services graph is the semantic index established on the UDDI registration center according to the logical relations between web services [1,2]. It can enhance the Web service discovery efficiency. jUDDI is an open source Java implementation of UDDI specification for Web Services. Based on the research on UDDI and Web service graph, this article takes jUDDI as an example to show how the traditional UDDI registry center can be extended so as to supporting Web service graph.

Using Web Services to Exchange Security Tokens for Federated Trust Management

Zhengping Wu,Alfred C. Weaver — 9/04/2007 05:26

In federated networks, trust management is critical to information sharing and online collaboration. Security tokens provide a way to convey and exchange trustrelated information for security and privacy purposes. Common users encounter difficulties when they have to handle security tokens across heterogeneous domains. Semantic gaps and incompatibilities are major barriers for trust-related information exchange in federated trust management. This paper uses intermediary-based, querybased and hybrid approaches to resolve these issues for different types of information in security tokens, and proposes three exchange models accordingly. This paper also provides a comprehensive framework using web services to exchange security tokens across security domains with suitable approaches and exchange models.

Toward Situational Secure Web Services Design Methods

Dhafer Thabet,Lamia Hassine,Henda Ben Ghezala — 9/04/2007 05:27

SWSD practices cannot be defined independently of the situation in which they are applied. To address this challenge, we propose an approach for guiding the construction and execution of situational SWSD methods by reusing and integrating different existing SWSD method components suited to the specific situation on hand.

A policy-based evaluation framework for Quality and Security in Service Oriented Architectures

V. Casola,A. R. Fasolino,N. Mazzocca,P. Tramontana — 9/04/2007 05:28

In dynamic cooperative architectures that are based on services (SOA), Customers are not only interested in service functionalities, but also in their quality, such as performance, cost, reliability, security and so on. In this scenario, models, techniques and tools supporting the selection of the best service are needed. In this paper, we propose an evaluation framework that includes a flexible quality meta-model for formalising Customer and Provider views of quality, and a decisional model defining a systematic approach for comparing offered and requested quality of services. We also illustrate the applicability of the framework in a Web Service(WS) scenario.

BPMO: Semantic Business Process Modeling and WSMO Extension

Zhixian Yan,Emilia Cimpian,Michal Zaremba,Manuel Mazzara — 9/29/2007 05:48

To actually bridge the gap between business perspective and technical perspective, the prerequisite is to provide a comprehensive process modeling framework for business processes. Different from the previous traditional process methodologies, our work is neither only industrial process graphic-modeling nor pure theoretical studies. We mainly focus on the semantically-enhanced process description model. We propose the semantic modeling framework for business processes, i.e. BPMO: basically, we determine the description requirements for the whole business process lifecycle involving process discovery, composition and execution; furthermore, we refine the comprehensive semantic Web services conceptual model WSMO and make specific extensions to realize the BPMO modeling framework.

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Intelligent Agents as Trust Negotiators for Federated Security

Arun Panayappan,Sriram Anand,Raghu P. Pushpakath — 9/04/2007 05:30

Competitive pressures on organizations force a need to rapidly build relationships with newer businesses. As desperate organizations begin to share business processes and solve each others problems, there is a need to share sensitive information. Though standards like WS- * attempt to offer security standards, they do not offer a mechanism to automatically negotiate trust levels in a federation of systems. This inability adversely affects the time to market.

Automatic Trust Negotiation is a process oriented approach to classify information, assign trust levels to cooperating businesses, upgrading or downgrading trust levels based on the qualities of the relationship.

This paper details a case study delivered to a large airline business. This case study demonstrates a service oriented Competitive decision making system which uses Intelligent Agents not only to negotiate based on business strategies but also the appropriate trust levels.

Research on Service-Oriented Workflow and Performance Evaluation

Bo Liu,Yushun Fan — 9/29/2007 05:50

The advent of SOA and Grid technology has brought new challenges to workflow operation and performance evaluation. In this paper, the characteristics of service-oriented workflow are presented, based on which the service-oriented workflow performance evaluation model is described and the performance analysis methods are depicted. Finally the design and implementation of our prototype system are introduced briefly.

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Aspect Separation in Web Service Orchestration: A Reflective Approach and its Application to Decentralized Execution

R. Jimenez-Peris,M. Patino-Martinez,E. Martel-Jordan,R. Naranjo-Izquierdo — 9/04/2007 05:59

Web service orchestration is becoming widely spread for the creation of composite web services using standard specifications such as BPEL4WS. The myriad of specifications and aspects that should be considered in orchestrated web services are resulting in increasing complexity. This complexity leads to software infrastructures difficult to maintain with interwoven code involving different aspects such as security, fault tolerance, distribution, etc. In this paper, we present ZenFlow a reflective BPEL engine that enables to separate the implementation of different aspects among them and from the implementation of the regular orchestration functionality of the BPEL engine. We illustrate its capabilities and performance exercising the reflective interface through a decentralized orchestration use case.

Policy-based Runtime Partner Management in ProcessBased Services

Fuyuki Ishikawa,Nobukazu Yoshioka,Shinichi Honiden — 9/29/2007 05:51

BPEL and similar languages have been provided a foundation for process-based implementation of composite Web services. These languages allow dejinition of orchestration processes without concrete binding information of involved partners. Although this approach facilitates customization of service discovery and selection before process execution, partner management during process execution has not been considered, such as rebinding of service providers upon events. In response to this problem, this study proposes a description model that facilitates runtime partner management in process-based services. The proposed model includes policy descriptions that allow insertion and customization of binding behavior according to surrounding environments and user preferences. The model also includes extensions in the standard process notation in order to allow process developers to give constraints to avoid adoption of inadequate policies as well as to dejine handlers to have common rebinding behavior reused. The proposed descriptions have been implemented and used in an agent framework for multimedia services.

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Integrating a Context Model in Web Services

Bouchra Soukkarieh,Florence Sedes — 9/04/2007 06:00

Nowadays, with the great diffusion of mobile technology, and ubiquitous systems, the context has become the ear and the eye of information systems. These systems are more and more based on the usage of Web Services. The classical architecture of these Services that allows an interoperable interaction between service users and providers does not take in account context adaptation.

In this article, we aim to integrate context adaptation within the classical architecture of Web Services, adding to it dedicated components that would return to nomadic users a list of Web Services that are adapted not only to his profile but also to his context.

Efficient XML-Based Grid Middleware Design for Multi-Core Processors

Rajdeep Bhowmik,Chaitali Gupta,Madhusudhan Govindaraju,Aneesh Aggarwal — 9/04/2007 06:01

Chip multi-processors (CMPs), commonly referred to as multi-core processors, are being widely adopted for deployment as part of the grid infrastructure. In CMPs, multiple cores can independently execute different threads. This change in computer architecture requires corresponding design modifications in programming paradigms, including grid middleware tools, to harness the opportunities presented by multicore processors. Simple and naïve implementations of grid middleware on multi-core systems can severely impact performance. The goal of developing an optimized multi-threaded grid middleware for emerging multi-core processors will be realized only if researchers and developers have access to an in-depth analysis of the impact of several low level microarchitectural parameters on performance. None of the current grid simulators and emulators provides feedback at the micro-architectural level. We have designed an emulation framework, Multi-core Grid (McGrid), to analyze and provide insightful feedback on the performance limitations, bottlenecks, and optimization opportunities for grid middleware on multi-core systems.

Aspect-Oriented Web Services for Distributed Resource Monitoring in Utility Computing

Trieu C. Chieu,Hoi Chan — 9/29/2007 05:52

Monitoring resource utilization is an essential task in Utility Computing (UC). Typically, a UC manager with adaptors is used to orchestrate and collect the monitoring results. However, large IT systems, such as those in data centers are required to monitor dynamic resources running in distributed platforms, thus demanding a complex UC manager structure. This paper introduces a novel approach that utilizes a platform specific Aspect- Oriented Programming (AOP) tool to dynamically weave a monitoring Web service into a running resource to enable communication with a UC manager exposed with standard monitoring Web service interfaces. This AOWeb service approach provides a simple yet powerful and effective means for the dynamic monitoring of distributed resources running in heterogeneous platforms.

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On the method for realizing globally and locally accessible resource management for WS-GRAM

Hidehiro Kanemitsu,Yoshiyori Urano — 9/29/2007 05:52

In recent years, Web Service technologies are becoming more and more important communication scheme for Grid environment. WSRF-based resource management components, such as WS-GRAM[4] in GT4[3], lay emphasis on how to make existing procedures such as local scheduler be invoked via HTTP, so that they inevitably have two problems described below. (1)If assumed environment is cluster type Grid, each worker node does not have access scheme to any information included in Resource Property of master node. (2)As a result, the contents of information sent to clients is forced by the local scheduler and therefore clients can not control job status in accordance with their own policy. If those two problems are resolved, any client’s own resource management policy can be reflected on worker nodes. In this paper, we propose a method for resolving those problems in order to realize the interactive communication between clients and worker nodes for WSRF-based cluster Grid.

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Modeling and Inversion of Geophysical Well Logging Tool Responses in a Service-Oriented High Performance Computing Architecture

V. Polyakov,R. Kocian,D. Omeragic, T. Habashy — 9/04/2007 20:54

Recent advances of the computing industry in SOA infrastructure have made service oriented applications practically attainable in the field of high performance computing for earth sciences. We have applied SOA to modeling and inversion of geophysical well logs. Parallelized log simulators are accessible as a Web service to a variety of interpretation workflows. We have developed an HPC management infrastructure based on SOAP. It is a fit-for-purpose system with a low runtime overhead and a novel flexible job submission mechanism, suitable for applications running on multi-cluster environments. We describe the system architecture and discuss performance benchmarks, including a novel way of estimating performance on heterogeneous clusters.

Web Services Variation Façade - Domain Specific Reference Architecture for Increasing Integration Usability

Ethan Hadar,Mark Perreira — 9/04/2007 20:55

Providing a usable service is a well known requirement. However, integration use-cases variations and evolution needs usually result in the construction of a generic, coarse-grained service. Such services tend to be complicated in comparison to specific, fine grained, highly usable ones. The differences between complex and simple integration points should not make them mutually exclusive, but rather mutually supported according to practical use cases. This paper describes an architectural reference solution implemented as a Web service variation façade. The architecture defines two types of services: a simple, open access, domain specific business language type; and an access-controlled, complex, coarse type, based on licensing permits. Both types of services are constructed in accordance with relevant publishing policies. The first is ready to integrate with a simple contract, and the second requires preliminary integration negotiations with a detailed and usually complex contract. The solution differentiates between the variations in integration scenarios and the core product functionality, while using single deployment protocol that utilizes a licensing policy. It provides highly usable services as well as complex generic ones, while limiting changes from the external to the internal domain, and vice versa.

XML Schemas Based Flexible Distributed Code Generation Framework

Madhusudhan Govindaraju — 9/04/2007 20:55

To leverage the strengths of different distributed systems, a user may want to develop an application that spans multiple frameworks. Currently, in such cases a user needs to use a different code generator for each one of the distributed frameworks that the application incorporates. Learning the details of the interface specification and code generation tool for each one of these distributed frameworks is tedious and error-prone. Instead, it is desirable to present the user with a flexible code generation framework that leverages the wide variety of available XML-based tools and is capable of generating code for all distributed systems. Our work involves the design and implementation of an XML schema based toolkit that can serve as the universal code generation toolkit for distributed frameworks.

Design and Verification ofWeb Services Compositions in the Telecommunication Domain

9/29/2007 05:54

Telecommunication is a key area where the use of web services has an enormous potential to facilitate the development of powerful and complex functionalities on top of existing ones. At the same time, the specific features of TelCo applications (asynchronous, event-driven communications, handling concurrent, long-running transactions, dynamically evolving sets of partners) pose difficult challenges to the adoption of standard languages and tools for web services. In this work, based on our analysis of TelCo standards and applications, we discuss a set of orchestration patterns, and show how these can be modeled using the WS-BPEL language. We also address the issue of guaranteeing the correctness of such applications, providing an automated support for the formal analysis of their behavior.

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Ocean Observing Data Web Service and Application in Shipwreck Salvation of Taiwan Strait

Yuwu Jiang,Xin Zhang,Huasheng Hong,Tianhe Chi — 9/04/2007 21:00

In the ocean dynamical environment real-time observing system of Taiwan Strait and adjacent maritime region, multiple observing data such as remote sensing data, structured data and so on are produced by the observing net from airspace, ocean surface, underwater space and ocean bottom. The data sharing and web service is a key part to influence the application efficiency of the whole system. According to the characteristics of the oceanic dynamical environment of Taiwan Strait, the construction scheme of the observing net is introduced in this paper firstly. Then the architecture of the observing data sharing and web service system is introduced, which includes five parts, i.e. the observing data acquiring module, the data integration module, the data processing and information production development module, and the data sharing and web service module. Next, the user classification system and service content classification are introduced. At last, the technology realization strategy and application in shipwreck salvation is introduced.

An MDA-based Approach for Specifying Semantic Portals

Muzammil Khan,Zaki Malik — 9/04/2007 21:01

We propose an approach to leverage the development life cycle of a semantic portal through the use of Object Management Group’s Model Driven Architecture (MDA). In our proposed approach, developers can use their prior knowledge about system modeling and UML to create semantic applications, without worrying much about various ontologic intricacies. We believe that our proposed combination of the semantic technologies and MDA-centric standardizations makes an ideal contrivance for the integration and development of standardized knowledge-based applications.

Using the Functional Model for Customizable Web Services Specification

Yacine Sam,Omar Boucelma — 9/04/2007 21:02

We present in this paper a functional model based framework for customizable Web services description, discovery and composition. Web services are described here at a high level abstraction and can be seen as "black boxes" labeled by their names and input/output parameters. Complementary to this formalism, we defined a set of mechanisms for Web services discovery and composition.

Modeling Autonomic Recovery in Web Services with Multi-tier Reboots

Rui Zhang — 9/04/2007 04:52

In order to offer adequate guidance to the emerging reboot-based self-healing processes in web services, this paper presents probabilistic models to estimate the recovery time and disruption of recovering a service using multiple levels of reboot. A case study is conducted to demonstrate benefits of the models.

Mobile SOA: Service Orientation on Lightweight Mobile Devices

Renne Tergujeff,Jyrki Haajanen,Juha Leppanen,Santtu Toivonen — 9/04/2007 21:09

Recent developments in daily business life indicate demand for facilitating process execution on various environments, including mobile devices with limited capabilities. This paper summarizes our current research on extending Service Oriented Architecture to lightweight mobile devices. Status of necessary enabling technologies, programming interfaces, and the supporting device base was surveyed. Availability of both mobile consumption and provision of services are reviewed. Based on our research and concept demonstration, we conclude that full-fledged mobile participation in SOA is not far in the future, and that partial implementations can already be built.

Web Service Orchestration for Bioinformatics Systems: Challenges and Current Workflow Definition Approaches

Graciela Gonzalez,Janaka Balasooriya — 9/04/2007 21:10

The number of web services, applications, data sources and scripts available to biomedical researchers increases day by day. Complex analysis, annotation, and data integration could potentially be orchestrated from these services, if only they could be seamlessly connected. Biomedical researchers often do not have the time or expertise required to download, install, and adapt these tools, nor would the input and output formats required make this adoption easy. In this short paper, we provide a preview of the challenges that biomedical applications present to the use of web services, and explore existing workflow definition frameworks for web service orchestration. We conclude that the current offering of support software for this task is not at the level to be desired to provide a viable answer to the challenges of orchestrating complex service-based biomedical applications, but the benefits to be gained from such support invites further systematic research in this area.

Author Index

7/31/2007 02:23

Full Article Text:

DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/ICWS.2007.46