SAMOA: A Framework for a Synchronisation-Augmented Microprotocol Approach

We address programming abstractions for building protocols from smaller, reusable microprotocols. The existing protocol frameworks, such as Appia and Cactus, either restrict the amount of concurrency between microprotocols, or depend on the programmer, who should implement all the necessary synchronisation using standard language facilities. We develop J-SAMOA: a framework for a Synchronisation Augmented Microprotocol Approach in Java. It has been designed to allow concurrent protocols to be expressed without explicit low-level synchronisation, thus making programming easier and less error-prone. In this paper, we describe versioning concurrency control algorithms. They are used by the runtime system of our framework to guarantee that the concurrent execution of a protocol is equivalent to a serial execution of its microprotocols. This guarantee, called the isolation property, ensures consistency of session or message-specific data maintained by microprotocols.