Research On Mobile Agent Based Heterogeneous Distributed Database Access Technology

With the development of computer networks, especially the rapid development of Internet, the distributed database system based on the network has had an extensive application in many fields. And the scale of database nodes becomes larger and larger. Accordingly, it plays more and more important role in the society life.Currently, most distributed database systems are based on the Client/Server model (also the Browser/Server model involved). And this kind of model is more suits for the application in the conventional network condition whose stability is more satisfactory. However, new problems have taken place when the system that based on Client/Server model is used in Internet which has the attributes just like the vast distributed database nodes, the different environments, the unstable network connections, and the huge quantity of information and so on. Mobile agent technology and the program language that can be planted to other platforms easily, Java, take a solution for these problems. So researchers presented distributed database access model based on mobile agent. This kind of model finds a more efficient way to access distributed database system because of the intensive distributed characters of mobile agent which can resolve some limitation of the conventional Client/Server model.The mainly purpose of this thesis is to research the issue how to make the mobile agent technology better used in the distributed database access. In this thesis, the architecture and character of the distributed database system and the mobile agent technology are generally analyzed. Moreover an improved distributed database access model is designed based on the original access model.In this thesis, besides the concept, architecture and feature of the distributed database system and mobile agent being introduced, some problems that the distributed database system currently faced are analyzed. Meanwhile, the mobile agent technology may give a hand to resolve these problems. At the same time, some improve on the original access model based on mobile agent is made. In the improved model, a service agent subsystem in the local database node is designed which can provide better service to the mobile agent who has the data request task. Besides the data query service provided, the new access model can control the local transaction of local data updating operation. Moreover, the service agent subsystem also designed a data access pool that can ensure that the resource which the global access tasks can use will be limited in a...