| As Trobus, a middleware product compliant with CORBA V2.3 Specification, is still based on the standard synchronous method invocation, it doesn't work in some applications such as order/purchase system, real-time control system and information publishing system, etc. In this thesis, a service system was developed on Trobus to provide communication decoupling and active services, which is compliant with CORBA Event Service Specification. it also provides event filter, service quality control, information exchange and concurrent service, etc.Basic theories are systematically introduced firstly in this thesis, including CORBA Event Service Specification, CORBA Notification Service Specification, Asynchronous Communication Model, Message Queue and multi-thread technique. Then, this thesis illuminates the design of the system and its architecture. At last, it describes how these basic theories were applied to developing the service system. In this section, some key points are explained in detail including the design and implementation of adapter interface in proxy layer, QoS pertinent objects, event transfer, event filter, information exchange and the combination of multi-thread and asynchronous communication model. Furthermore, design patterns, such as Observer and Adapter, are extensively used in the system not only to solve the design problems, but also to make the design of the system abstract, standard and reusable.The service system provides a new way to implement Event Service in a CORBA system. The main characteristic of it is the combination of asynchronous communication model and multi-thread to improve performance. Asynchronous communication model makes it possible that single-thread to some extent can provide the same performance as synchronous multi-thread, while avoids the shortcomings of multi-thread. This tradeoff can reach high performance with better throughput and scalability, especially in heavily situation. |
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