A Formal Approach for the Validation of Web Service Orchestrations

Service Oriented Architecture (SOA) is an emerging computing model that aims to build new software, by assembling independent and loosely coupled services. This composition can be described from both a local or a global perspective by respective orchestration or choreography. In fact, the main focus of this paper is to validate a web service orchestration through the verification of properties. This verification must take into account both generic and specific properties. The generic properties can be checked for any invoked web services when the specific properties are different interdependence relationships between activities within an orchestration process. These properties cannot be directly verified on the process, so, we have to use formal techniques. Doing so, we will present, in this paper, our formal approach to validate a web service orchestration. The paper adopts WS-BPEL 2.0 as the language to describe the web service orchestration and uses the SPIN model-checker for the verification engine. The WS-BPEL specification is translated into Promela code which is the input language for SPIN model-checker, in order to check generic and specific properties expressed with LTL (Linear Temporal Logic). A tool named Bpel VT (BPEL Verification Tool) is developed to support the proposed approach. It provides the WS-BPEL manager, the automated process translation of WS-BPEL to Promela code and model-checking views.