Qos Adaptive Services, Component Design And Research

At present, distributed dynamic QoS (Quality of Service) requirements must be offered while meeting the functional requirements (such as real-time, safe, reliable) in many distributed applications. However, most distributed object middleware, such as the OMG's CORBA, Microsoft's DCOM, can not provide effective dynamic QoS.So, how to implement dynamic QoS adaptive mechanism is deemed to the main problem of performance in distributed applications.Component technology is considered the key technology to increase the rate of re-use and improve development efficiency. So, a component model is proposed for QoS adaptive mechanism. According to the model, a component-based application framework for QoS adaptive services is designed. In the thesis, some key issues about component, such as component description, component assembly and deployment are researched. Major work can be summarized as following:1. Research and implement mechanism of specifying and measuring QoS in distributed applications.2. Research the main description and implement methods of component. Propose the necessity of component description model on ontology from semantics.3. Design component model QAC for QoS adaptive mechanism. Implement the QAC based on ACE+TAO+CIAO and give a component-based application framework for QoS adaptive services.4. Propose a semantic-based, common component description method and design the description language QCDL.5. Research how to assemble component into QoS adaptive service. Based on QCDL, design a"glue code"generator, give the deployment methods.6. Design application of security adaptation.The result shows that the combination of QoS adaptive mechanism and component technology makes the development of QoS adaptive services more flexible. The separation of performance and function module reduce the system complexity.