Publications in 2008

Articles in Refereed Conferences:

1. Moreno Marzolla, Raffaela Mirandola. Performance Prediction of Web Service Workflows. Software Architectures, Components, and Applications, Lecture Notes in Computer Science, Vol. 4880, pages 127-144, January 2008.
   Abstract: Web Services play an important role in the SOA paradigm, as they allow services to be selected on-the-fly to build applications out of existing components. In this scenario, the BPEL notation can be used as an orchestration language which allows the user to describe interactions with Web Services in a standard way. The performance of a BPEL workflow is a very important factor for deciding which components must be selected, or to choose whether a given sequence of interactions can provide the requested quality of service. Due to its very dynamic nature, workflow performance evaluation can not be accomplished using traditional, heavy-weight techniques. In this paper we present a multi-view approach for the performance prediction of service-based applications encompassing both users and service provider(s) perspectives. As a first step towards the realization of this integrated framework we present an efficient approach for performance assessment of Web Service workflows described using the BPEL notation. Starting from annotated BPEL and WSDL specifications, we derive performance bounds on response time and throughput. In such a way users are able to assess the efficiency of a BPEL workflow, while service provider(s) can perform sizing studies or estimate performance gains of alternative upgrades to existing systems. To bring this approach to fruition we developed a prototype tool called bpel2qnbound, using which we analyze a simple case study.

2. Sheng Chen, Liang Bao, Ping Chen. OptBPEL: A Tool for Performance Optimization of BPEL Process. Software Composition, pages 141-148, 2008.
   Abstract: The Business Process Execution Language (BPEL) is now a de facto standard for specifying and executing business process for web service composition and orchestration. As more and more web services are composed using BPEL, tuning these compositions and gain better performance becomes increasingly important. This paper presents our approach for optimizing the BPEL process and introduces OptBPEL, a tool for performance optimization of BPEL process. The approach starts from the optimization of synchronization structure concerning link in BPEL. After that, some concurrency analysis techniques are applied to obtain further performance improvement. Finally, we give some experiments and prove the efficiency of these optimization algorithms used in OptBPEL.

3. Kyriakos Kritikos, Dimitris Plexousakis. Evaluation of QoS-Based Web Service Matchmaking Algorithms. International Conference on Services Computing, 2008.
   Abstract: Web Service (WS) discovery is a prerequisite for achieving WS composition and orchestration. Although a lot of esearch has been conducted on the functional discovery of WSs, the proposed techniques fall short when faced with the foreseen increase in the number of (potentially functionally- equivalent) WSs. The above situation can be resolved with the addition of non-functional (Quality of Service (QoS)) discovery mechanisms to WS discovery engines. QoS-based WS matchmaking algorithms have been devised for this reason. However, they are either slow - as they are based on ontology reasoners - or produce inaccurate results. Inaccuracy is caused both by the syntactic matching of QoS concepts and by wrong matchmaking metrics. In this paper, we present two Constraint Programming (CP) QoS-based WS discovery algorithms for unary constrained WS specifications that produce accurate results with good performance. We also evaluate these algorithms on matchmaking time, precision and recall in different settings in order to demonstrate their efficiency and accuracy.