Web Services: A Process Algebra Approach

It is now well-admitted that formal methods are helpful for many issues raised in the Web service area. In this paper we present a framework for the design and verification of WSs using process algebras and their tools. We define a two-way mapping between abstract specifications written using these calculi and executable Web services written in BPEL4WS. Several choices are available: design and correct errors in BPEL4WS, using process algebra verification tools, or design and correct in process algebra and automatically obtaining the corresponding BPEL4WS code. The approaches can be combined. Process algebra are not useful only for temporal logic verification: we remark the use of simulation/bisimulation both for verification and for the hierarchical refinement design method. It is worth noting that our approach allows the use of any process algebra depending on the needs of the user at different levels (expressiveness, existence of reasoning tools, user expertise)

Automated maintenance of service compositions with SLA violation detection and dynamic binding

Web service compositions need to adapt to changes in their constituent web services, in order to maintain functionality and performance. Therefore, service compositions must be able to detect web service failure and performance degradation resulting in the violation of service-level agreements. Automated diagnosis and repair are equally important. However, existing standards and languages for service compositions, such as BPEL, lack constructs for web service monitoring and runtime adaptability, which are pre-requisites for diagnosis and repair. We present a solution for transparent runtime monitoring, as well as automated performance degradation detection, diagnosis, and repair for service compositions expressed as BPEL processes. Our solution uses lightweight monitoring techniques, supports customizable diagnosis and repair strategies, and is compatible with any standards-compliant BPEL engin

Specification and analysis of SOC systems using COWS: a finance case study

Service-oriented computing, an emerging paradigm for distributed computing based on the use of services, is calling for the development of tools and techniques to build safe and trustworthy systems, and to analyse their behaviour. Therefore many researchers have proposed to use process calculi, a cornerstone of current foundational research on specification and analysis of concurrent and distributed systems. We illustrate this approach by focussing on COWS, a process calculus expressly designed for specifying and combining services, while modelling their dynamic behaviour. We present the calculus and one of the analysis techniques it enables, that is based on the temporal logic SocL and the associated model checker CMC. We demonstrate applicability of our tools by means of a large case study, from the financial domain, which is first specified in COWS, and then analysed by using SocL to express many significant properties and CMC to verify them