Highly available and reliable communication protocols for heterogeneous systems

Existing and legacy software systems are the product of lengthy and individual development histories. Interoperability among such systems offers the support of global applications on these systems. However, interoperability among these heterogeneous systems is hampered by the absence of a reliable communication environment that supports the development of global applications.In this paper, we show how a generic communication framework can serve as a testbed for the specification, verification, and execution of distributed communication protocols. The development of distributed, global concurrency protocols is much simpler than using traditional tools, like RPC (remote procedure call), because our framework provides a high-level communication mechanism that frees the protocol designer from thinking in a message-based style. We present several protocols that are consistent with realistic assumptions about local database systems, and proofs of their correctness and consistency preservation. We also show that the execution of these protocols is fault-tolerant. The distribution of systems can be chosen according to application requirements, without adaptation of protocols. Fault tolerance can be fine-tuned within the framework itself, so that verified protocols do not need modifications in this case either.Besides protocols for traditional transaction processing, we present communication protocols for advanced transaction models that relax one or more of the ACID properties of transactions. These advanced transaction models enable local autonomy and thus are much better suited for heterogeneous environments.