Research On Design And Implementation Of Reliable Message Transfer Service

As a fundamental technique for distributed system integration, message transfer provides a reliable asynchronous communication mechanism for loosely-coupled processes. Thus, a modern distributed application relies heavily on reliable message transfer service. However, the infrastructures of distributed systems are inherently fault-prone, which brings a serious challenge to the implementation of reliable message transfer service.As a component of message oriented middleware ISMQ, Message Transfer Agent(MTA), which implements reliable message transfer service, delivers messages among ISMQ servers. Based on the study of failure models, we introduced a reliable message transfer protocol in MTA. This protocol specifies behavior of communication participants and guarantees exactly-once delivery of messages in any kind of failure situations. By exploiting key implementation techniques, MTA system is then enhanced in the following two aspects: first, network and system resource usage is optimized; second, adaptability and manageability of MTA is improved. Cluster is the mainstream approach to improve availability and performance of a message middleware. In this thesis, we bring forth a cluster solution for MTA and client connection handling component of ISMQ. Analysis shows that this solution can dramatically improve the availability and performance of MTA and CM. At last, by the observation that this solution is applicable to more applications other than message middleware, we put forward a general cluster framework OOACF for three-tired distributed systems. Application scope of this framework is also presented by the analysis on advantages and disadvantages of OOACF.