Design And Implementation Of Distributed Retrieval Information System Based On Mobile Agent

Along with the development of Internet technology, how to establish highly effective, safe and the vigorous application system under the distributed environment has become one of current research hot points. The distributed computing infrastructure has experienced the terminal/mainframe architecture, file server centered network architecture, the C/S architecture, the B/S architecture and the multilayer architecture based on Internet/Intranet, In recent years, Mobile Agent technology is considered to be an easily to design, realize and maintained new technology under Internet/Intranet environment, and becomes the research hot point in academic and business communities.Mobile Agent has the motion characteristic. It is independent of machine and can move from one machine to another, and completes the task on behalf of the user. Mobile Agent technology involves the computer network, the distributional system, the artificial intelligence and many other kinds of domains. Because the characteristic of mobility, independency and coordination, it has already applied in the Internet environment, and demonstrated huge prospect and superiority.The main purpose of this thesis is to explore concrete application of mobile agent technology to construct distributed system and study some problems and their solutions when we apply mobile agent technology in software development. The software development method based on mobile agent was analyzed in detail after having studied the basic concepts and application characteristics of mobile agent. Then a distributed multi-database retrieval information system model was proposed. This thesis elaborates the software agent concept, and gives an integrity introduction to essential techniques, the technical superiority and security of mobile agent's structure. Then it describes an information service model based on mobile agent, and proposes a distributed multi-database retrieval information system model based on this foundation. The subsystem's constructions and their reciprocity have been analyzed;an agent dock system to solve agent migration expiration and a communicationmanagement system to solve the correspondence expiration have been designed, so that it has provided a safety mechanism for users and information sources. The thesis explores in detail the mobile agent soft development kit Aglet and its programming mechanism, elaborates the Aglet event model and the message transmit mechanism, which provide key support for the correct programming. Using Aglet as development platform and unifying other technologies, we have implemented this model, and tested it on the Linux networking environment, the Windows operating system and the MySql, SqlServer database system. At last the superiority and insufficiency using mobile agent technology to develop a distributed system have been discussed.