Towards correct Evolution of Conversation Protocols

Distributed software systems change dynamically due to the evolution of their environment and/or requirements, their internal designing policies, and/or their specification bugs which must be fixed. Hence, checking system changes must be run continuously. Such systems are usually composed of distributed software entities (called peers) interacting with each other through message exchanges, and this is to fulfil a common goal. The goal is often specified by a conversation protocol (CP), i.e. sequences of sent messages. If there exists a set of peers implementing CP, then CP is said to be realisable. In this paper, we propose a stepwise approach for checking whether an evolution, i.e. adding and/or removing messages and/or peers, can be applied to a CP that was realisable before updating it.We define a set of correct evolution patterns and we suggest an algebra of CP evolution. Our approach ensures that CP evolution preserves the realisability condition

Handling Reparation in Incremental Construction of Realizable Conversation Protocols

International audienceA main concern, already addressed by the research community, relates to the verification of Conversation Protocol (CP) realizability, which means the existence of a set of peers whose communication behavior is equivalent to a given conversation protocol.In this paper, we consider the incremental repairability of CPs identified as un-realizable using the set of composition operators, defined in that satisfy suficient conditions for realizability preservation. Reparation consists in identifying a set of changes completing intermediate un-realizable CPs so that the resulting CP becomes realizable. Our proposal is validated through a successful application of the presented approach on un-realizable CPs borrowed from the literature

Incremental Construction of Realizable Choreographies

International audienceThis paper proposes a correct-by-construction method to build realizable choreographies described using conversation protocols (CPs). We define a new language consisting of an operators set for incremental construction of CPs. We suggest an asynchronous model described with the Event-B method and its refinement strategy, ensuring the scalability of our approach

Correct-by-Construction Evolution of Realisable Conversation Protocols

International audienceDistributed software systems are built by composing independent and autonomous peers with cross-organisational interaction and no centralised control. These peers can be administrated and executed by geographically distributed and autonomous companies. In a top-down design of distributed software systems, the peers’ interaction is often described by a global specification called Conversation Protocol (CP) and one have to check its realisability i.e., whether there exists a set of peers implementing this CP. In dynamic environments, CP needs to be updated wrt. new environment changes and end-user interaction requirements. This paper tackles CP evolution such that its realisability must be preserved. We define some evolution patterns and prove that they ensure realisability. We also show how our proposal can be supported by existing methods and tools based on refinement and theorem proving, using the event-B language and RODIN development tools