Patterns And A Rchitectures Basedon Message-oried Middceware

With the development of network distributed computing, the characteristics of distributed applications bring many challenges to the software architecture and developing methods. Middleware and design patterns are two effective solutions to these challenges. Middleware lies between the system platforms layer and the application layer, connecting distributed components together. Design patterns guide developers to reusable paradigms for repeatedly emerging issues. Although many design patterns have been devised, they are insufficient in constructing middleware and distributed applications. This thesis provides patterns and architectures for middleware and distributed applications, including connection management, communication manners and quality of service. Connection management is a universal module inside many middleware. In the client side, we provide the asynchronous interface pattern. In the server side, the service reactor pattern accepts requests and visits the service. The handle-descriptor pattern maps local references to the remote. The asynchronous thread pool pattern transfers asynchronous operations to separate threads. The combination of these patterns forms the architecture of connection management. Point-to-point and publish/subscribe are two effective communication styles for distributed applications. Point-to-point style uses queue as intermediate storage, thus obtaining asynchronism. Publish/subscribe style associates components by topic, thus obtaining anonymity. Owing to the reliability and scalability of message queue, we give a message-queue implementation of publish/subscribe system. Quality of service is an essential aspect of a middleware. We construct a QoS model for message-oriented middleware, and provide the corresponding QoS control mechanisms. Finally, we prospect the future of patterns and pattern systems for middleware and distributed applications, and discuss further work.