HIGHLY AVAILABLE AND RELIABLE COMMUNICATION PROTOCOLS FOR HETEROGENEOUS SYSTEMS

Existing and legacy software systems are the product of lengthy and in dividual development histories. Interoperability among such systems of fers the support of global applications on these systems. However, int eroperability among these heterogeneous systems is hampered by the abs ence of a reliable communication environment that supports the develop ment of global applications. In this paper, we show how a generic comm unication framework can serve as a testbed for the specification, veri fication, and execution of distributed communication protocols. The de velopment of distributed, global concurrency protocols is much simpler than using traditional tools, like RPC (remote procedure call), becau se our framework provides a high-level communication mechanism that fr ees the protocol designer from thinking in a message-based style. We p resent several protocols that are consistent with realistic assumption s about local database systems, and proofs of their correctness and co nsistency preservation. We also show that the execution of these proto cols is fault-tolerant. The distribution of systems can be chosen acco rding to application requirements, without adaptation of protocols. Fa ult tolerance can be fine-tuned within the framework itself, so that v erified protocols do not need modifications in this case either. Besid es protocols for traditional transaction processing, we present commun ication protocols for advanced transaction models that relax one or mo re of the ACID properties of transactions. These advanced transaction models enable local autonomy and thus are much better suited for heter ogeneous environments.