Section: New Results

Service-oriented computing

Participants : Maurizio Gabbrielli, Elena Giachino, Saverio Giallorenzo, Claudio Guidi, Mario Bravetti, Ivan Lanese, Michael Lienhardt, Jacopo Mauro, Fabrizio Montesi, Gianluigi Zavattaro.

Orchestrations

Orchestration models and languages in the context of Service-Oriented Architectures (SOA) are used to describe the composition of services focusing on their interactions. Coloured Petri nets (CPN) offer a formal yet easy tool for modelling interactions in SOAs, however mapping abstract SOAs into executable ones requires a non-trivial and time-costly analysis. In [34] , we propose a methodology that maps CPN-modelled SOAs into Jolie SOAs (our target language), exploiting a collection of recurring control-flow patterns, called Workflow Patterns, as composable blocks of the translation. We validate our approach with a realistic use case. In addition, we pragmatically assess the expressiveness of Jolie with respect to the considered WPs.

Choreographies

Choreographies are high-level descriptions of distributed interacting systems featuring as basic unit a communication between two participants. A main feature of choreographies is that they ensure deadlock-freedom by construction. From a choreography one can automatically derive a description of the behaviour of each participant using a notion of projection. Choreographies can be used both at the level of types (multiparty session types) or as a programming language. In [18] we surveyed the work on choreographies and behavioural contracts in multiparty interactions. In [28] we explored the notion of deadlock freedom (the system never gets stuck), and the related notions of lock freedom (each action is eventually executed under a fair scheduling) and progress (each session never gets stuck). Previous work studied how to define progress in an open setting by introducing the notion of catalysers, execution contexts generated from the type of a process. We refined the notion of catalysers leading to a novel characterization of progress in terms of the standard notion of lock-freedom. We applied our results both to binary session types and in an untyped session-based setting. We combined our results with existing techniques for lock-freedom, obtaining a new methodology for proving progress. Our methodology captures new processes w.r.t. previous progress analysis based on session types. The two following works consider the extension of choreographies, which traditionally have a static structure, to deal with adaptation, i.e., dynamic changes of the structure of choreographies. A preliminary analysis of adaptable choreographies at the level of types is presented in [27] . This work considers both updates from inside the system (self-adaptation), and external updates. Adaptable choreographies as a programming language are considered in [33] , where we presented AIOCJ, a framework for programming distributed adaptive applications. AIOCJ allows the programmer to specify which parts of the application can be adapted. Adaptation takes place at run-time by means of rules, which can change during the execution to tackle possibly unforeseen adaptation needs. AIOCJ relies on a solid theory that ensures applications to be deadlock free by construction also after adaptation.