Situational Method Engineering (SME) is a prolific research domain where competing SME approaches have been defined and used for composing, adapting or/and configuring a method into modular constructs according to their own modularization vision since the late 90's. However, the diversity of these solutions implies some drawbacks constituting an obstacle to their usage in industry. The Method as a Service (MaaS) approach is proposed in this thesis to overcome this lack of consideration of situational methods usage dimension. In this approach we propose to rethink the SME domain with the service oriented paradigm according to the three actors of the service oriented architecture (service registry, provider and consumer). This solution includes four elements: the ontology of method components metamodels (OMCM), the atomic method service (AMS) metamodel, the method line (ML) metamodel and the MaaS Platform. The OMCM ontology is providing a semantic common ground for the SME approaches. This ontology is used to describe all method components in the same manner to publish them in a registry. The AMS and ML metamodels provide an interoperable service oriented solution for the tool support dimension of method components and methods. The ML metamodel incorporates the variability concept in the method definitions to facilitate their configurations and their adaptations. The Maas Platform architecture defines a frame for building method service execution platforms in different technologies like web portals or IDE. This thesis proposes to handle the tool support dimension and the variability concept in methods by providing an original service oriented reuse platform.
