| In the 90s, with the development of distributed computing, Distributed Object Computing (DOC) has been the main stream of distributed computing. Distributed Object Computing Environment called object middleware resolves problems of integrating distributed systems. Consequently, object middleware is the focus of DOC research. There are three representatives of object middleware technology, namely, OMG's CORBA, Microsoft's DCOM, and Sun's Java RMI. Among these, CORBA becomes the main stream of object middleware technology through support of platform and programming language independence, transparency, interoperability, and openness. However, current object middleware products, especially CORBA products, are inefficient, monolithic, static, and black-box software platforms due to multi-layer abstract of DOC and deficiencies of current object middleware technology. So, current object middleware products can't meet requirements of applications from different domains. As a result, the framework of object middleware to help open implementation and the technology applied to resolve problems mentioned above are one of main research focuses of object middleware.Therefore, the primary work of the thesis is mainly about the technology of efficient and flexible object middleware. The main work include the layered framework of object middleware to support open implementation, extensibility and customization, the technology for optimizing implementations of abstract layers of object middleware, the management and deployment environment of distributed objects, and dynamic reconfiguration of object middleware and distributed object systems. Based on these, we develop the efficient and flexible object middleware product according to the CORBA version 2.3. The primary contributions of this thesis include:1. The layered abstract model of DOC is accurately specified according to the essence of DOC. By means of combination of Agent technology and DOC, the main framework of object middleware is provided. The multi-layered framework of object middleware named ML-DOF is provided through applying aspect-oriented programming (AOP) and component technology to the main framework. ML-DOF opens inside interfaces and semantics of strategies of object middleware, partitions object middleware into some parts to support customization and extensibility. To overcome shortcomings of CORBA and RMI, the open model of ORB and the extended model of RMI are presented according to ML-DOF.2. In order to improve efficiency of object middleware, the thesis does research on optimization technology of abstract layers of DOC based on ML-DOF. The marshaling algorithm is provided to improve efficiency of compiled marshalling 13%~33% according to Common Data Representation. When the algorithm is applied to interpreted marshalling based on CORBA::Any type, the effect is better. Another algorithm to dispatch object in constant time and the framework to integrate different dispatching object strategies are presented. Also, the thesis provides a kind of optimization mechanism and the layered algorithm to customize the demultiplexing method strategy for every class of distributed object. The algorithm is provided to directly locate method, which has good space and timeefficiency. When we apply these to StarBus, the efficiency of StarBus can be improved 30% according to BenchMark presented by us.3. The thesis provides an optimization model of Collocated Invocation according to ML-DOF. The model accords with the essence of DOC and is efficient, servant-oriented and transparent to applications, conforms to CORBA specification and features, such as transparency and features of POA.4. In order to meet management requirements of distributed objects, the thesis presents the model of resource access based distributed object. By means of this model and reactive agent, the multi-layered management domain (MLMD) model of object middleware is provided, which divides object middleware into many layered management domains according to configurati...
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