Specification of Realizable Service Conversations Using Collaboration Diagrams

Specification, modeling and analysis of interactions among peers that communicate via messages are becoming increasingly important due to the emergence of service oriented computing. Collaboration diagrams provide a convenient visual model for specifying such interactions. An interaction among a set of peers can be characterized as a conversation, the global sequence of messages exchanged among the peers, listed in the order they are sent. A collaboration diagram can be used to specify the set of allowable conversations among the peers participating to a composite web service. Specification of interactions from such a global perspective leads to the realizability problem: Is it possible to construct a set of peers that generate exactly the specified conversations? In this paper we investigate the realizability of conversations specified by collaboration diagrams. We formalize the realizability problem by modeling peers as concurrently executing finite state machines and we give sufficient realizability conditions for a class of collaboration diagrams.