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This paper outlines the design and implementation of WSMQ, which is a message-oriented middleware specifically designed to enhance the reliability of Web services. Highlights of this application feature fault tolerance of Web services communication, Quality of Services including authentication and prioritization, security enhancement and performance improvements in Web services over the existing architecture. The implementation of these features aims to address the existing issues surrounding Web services, and further its advancement towards a new standard for distributed application development. 1.

In this paper, we address the problems related to the performance modeling of object based software systems, distributed across multiple platforms. Classical flat queuing models seem to be inappropriate, because of the inevitable complexity caused by the platform heterogeneity and the dual client/server role that objects often play in their interactions. Models should be structured vertically, in hierarchical levels, as well as horizontally, in interconnected model components. Each component may be using several analytically intractable queuing network extensions, for the precise representation of the synchronization phenomena that arise in the various object interaction cases. The overall model structure is utilized not only for incrementally specifying a complex workload and resource contention description, but also for approximately analyzing it, by successive flow equivalence aggregations. In this context, we discuss the properties that the model should possess, for achieving satisfactory levels of accuracy. The modeling of common design cases, like the synchronous object invocation, the distributed callback and the multithreading process structure, is illustrated, in the context of CORBA based object interactions. The suggested approach promotes the accomplishment of the appropriate type of analysis at the most suitable level of abstraction, in respect to the specific credibility and cost requirements of each study.