Nesting Actions through Asynchronous Message Passing: the ACS Protocol

Rachid Guerraoui, Riccardo Capobianchi, Agnes Lanusse, Pierre Roux

Abstract: This paper describes an original object communication protocol, named ACS (Apply, Call, Send), that we adopted in KAROS (Kernel of an Action-based Reliable Object System) to deal with concurrency control and failure recovery in distributed applications. The basic idea in ACS is to associate each request message to an atomic action. ACS allows to build atomic action trees representing the logical nesting of services. Moreover, it gives to the programmer full control on the granularity of atomicity and provides a fairly natural model for grouping objects inside actions to ensure the system's global consistency. By using ACS, objects may be seen as reliable elements that can be composed to build up reliable distributed applications.