We present a type theory for analyzing concurrent multiparty interactions as found in service-oriented computing. Our theory introduces a novel and flexible type structure, able to uniformly describe both the internal and the interface behavior of systems, referred respectively as choreographies and contracts in web-services terminology. The notion of conversation builds on the fundamental concept of session, but generalizes it along directions up to now unexplored; in particular, conversation types discipline interactions in conversations while accounting for dynamical join and leave of an unanticipated number of participants. We prove that well-typed systems never violate the prescribed conversation constraints. We also present techniques to ensure progress of systems involving several interleaved conversations, a previously open problem. 1

Abstract. We propose a methodology for statically predicting the possible interaction patterns of services within a given choreography. We focus on choreographies exploiting the event notification paradigm to manage service interactions. Control Flow Analysis techniques statically approximate which events can be delivered to match the choreography constraints and how the multicast groups can be optimised to handle event notification within the service choreography. 1

Abstract. In this paper we present a logic-based technique for verifying both security and correctness properties of multilevel service compositions. We define modal µ-calculus formulae interpreted over service configurations. Our formulae characterize those compositions which satisfy a non-interference property and are compliant, i.e., are both deadlock and livelock free. Moreover, we use filters as prescriptions of behavior (coercions to prevent service misbehavior) and we devise a model checking algorithm for adaptive service compositions which automatically synthesizes an adapting filter. 1

Abstract. Choreographies and Contracts are important concepts in Service Oriented Computing. Choreographies are the description of the behaviour of a service system from a global point of view, while contracts are the description of the externally observable message-passing behaviour of a given service. Exploiting some of our previous results about choreography projection and contract refinement, we show how to solve the problem of implementing a choreography via the composition of already available services that are retrieved according to their contracts.

Abstract. Communication protocols in distributed systems often specify the roles of the parties involved in the communications, namely for enforcing security policies or task assignment purposes. Ensuring that implementations follow role-based protocol specifications is challenging, especially in scenarios found, e.g., in business processes and web applications, where multiple peers are involved, single peers impersonate several roles, or single roles are carried out by several peers. We present a typebased analysis for statically verifying role-based multi-party interactions, based on a simple π-calculus model and prior work on conversation types. Our main result ensures well-typed systems follow the role-based protocols prescribed by the types, including systems where roles have dynamic distributed implementations. 1