Une Approche de Composition de Services Dynamiques : application aux Systèmes Collaboratifs

Abstract

The composition of services is a process of grouping several services into a single service to perform important functions. In recent decades, many languages have been proposed for their modeling. Most of them are based on process-oriented approaches. The latter produce imperative languages, which are rigid to change because they focus on how processes should be constructed. Despite the fact that semantics are introduced in languages to increase their exibility, dynamism is limited to nding services that have disappeared or have become defective. They do not o er the possibility of adapting the composite service to the execution. Although rule-based languages have been introduced, they describe constraints to guide the construction of composite services, they remain very dependent on BPML which is the underlying technology and are centralized. This thesis proposes the speci cation of a purely declarative language based on rules for the composition of services in a peer-to-peer environment. A declarative approach has properties of exibility, adaptability, reusability and even formal semantics. First, we propose a declarative language named GSLang for the composition of services. We de ne a composite service as a rule of production of a grammar with a left-hand side (LHS) which is the service to de ne and a right-hand side (RHS) being the services required to realize the LHS service. The syntactic categories presenting the concepts of GSLang and a formal description of the operational semantics which highlights dynamism, exibility and adaptability are de ned. Next, a veri cation framework is designed. Using the Model Driven Engineer, we de ne a meta-model for the GSLang language. The veri cation framework translates the GSLang service speci cations into the Promela language for the veri cation. The latter makes it possible to verify in particular that a service speci cation GSLang is resolved. Finally, a set of tools is proposed consisting of an editor for the GSLang speci cations, a transformation engine and an execution engine. Finally, a case study of a simpli ed mission management system is presented in order to show how to specify a system completely using our approach and highlighting its properties.