We propose a new conceptual model for choreographies of web-services. Choreographies are seen as virtual workflow models shared among participants. Subsets of these participants might have more refined models known only to them. So we see choreographies actually as federations of process models (choreographies as well as orchestrations). In this paper we discuss this layered concept, and present a metamodel with the following distinguishing features: It is fully distributed and does not require a central or global authority. It captures the control flow and the data flow aspects of the processes. Choreography models can be (re)used in several other choreographies. Additionally, we provide a procedure which checks whether choreographies fit together, i.e. the conformance of the federation relationship between models. Work partly supported by the Commission of the European Union within the project WS-Diamond in FP6.STREP.

Top