Section: New Results

Service-oriented computing

Participants : Maurizio Gabbrielli, Elena Giachino, Saverio Giallorenzo, Claudio Guidi, Mario Bravetti, Cosimo Laneve, 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. Concrete web services are connected to abstract service definitions for the aim of service discovery. In [16] we study a natural notion of compliance between clients and services in terms of their bpel (abstract) descriptions. The induced preorder shows interesting connections with the must preorder and has normal form representatives that are parallel-free finite-state activities, called contracts. Moreover, in [22] we focus on advancements of the orchestration language Jolie aiming at the development of dynamically adaptable orchestrated systems.

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 [19] we surveyed our results about verification of adaptable processes, focusing in particular on distributed adaptability, where a process can update part of a protocol (specified by a choreography) by performing dynamic distributed updates over a set of protocol participants. In [14] we illustrate our approach to develop and verify distributed, adaptive software systems. The cornerstone of our framework is the use of choreography languages, which allow us to obtain correctness by construction. Moreover, in [36] we present DIOC, a language for programming distributed applications that are free from deadlocks and races by construction. A DIOC program describes a whole distributed application as a unique entity (choreography). DIOC allows the programmer to specify which parts of the application can be updated. At runtime, these parts may be replaced by new DIOC fragments from outside the application. DIOC programs are compiled, generating code for each site, in a lower-level language called DPOC. As a consequence DPOC applications are free from communication deadlocks and races, even in presence of runtime updates.