A RuleBased Language and Verification Framework of Dynamic Service Composition The emergence of BPML (Business Process Modeling Language) has favored the development of languages for the composition of services. Processoriented approaches produce imperative languages, which are rigid to change at runtime because they focus on how the processes should be built. Despite the fact that semantics is introduced in languages to increase their flexibility, dynamism is limited to find services that have disappeared or become defective. They do not offer the possibility to adapt the composite service to execution. Although rulesbased languages were introduced, they remain very much dependent on the BPML which is the underlying technology. This article proposes the specification of a rulebased declarative language for the composition of services. It consists of the syntactic categories which make up the concepts of the language and a formal description of the operational semantics that highlights the dynamism, the flexibility and the adaptability of the language thus defined. This paper also presents a verification framework made of a formal aspect and a toolset. The verification framework translates service specifications into Promela for model checking. Then, a validation framework is proposed that translates the verified specifications to the operational system. Finally, a case study is presented.

Formal specification and validation of refinement from WSCDL to BPEL Service composition is a primary task in the development of serviceoriented systems. The Web Service Process Execution Language (WSBPEL) and the Web Service Choreography Descriptor Language (WSCDL) are two major languages for Web services modeling and implementation. Although these two composition models are of a different nature, they are complementary. WSCDL serves as a behavioral modeling language for collaboration between multiple participants (web services) within the same business process from a global point of view. However, WSBPEL allows a service composition process to be described at different levels of abstraction. At a high level, the description follows a global point of view and deals only with the exchange of messages between participating abstract services (represented abstractly by roles). WSCDL descriptions are thus considered as a specification of the abstract service composition from which more concrete WSBPEL processes are extracted. In this article, we present a formal modeling and analysis approach based on sequential communication process (CSP) in order to verify the behavioral consistency between abstract choreographic descriptions and executable BPEL processes, thereby proving the correctness of the translation process.