| In the construction process of a highway project, because the interrelated distributed database is huge and complex, which is hard for traditional distributed query system to effectively handle it. Designing a new distributed query system which can reduce the burden of network and asynchronously process real-time work effectively and reliably is quite important and imminently.A highway project query system is discussed by this thesis. Main work is as follows:1. The technology of Mobile Agent is researched first, after that structure of Mobile Agent is analyzed, the application advantage and key technology of Mobile Agent are concluded and summarized.2. Framework of the highway project query system is presented and is divided into three subsystems which are user interface subsystem, data service system and management control subsystem and all three parts are designed in detail.3. In the process of designing subsystems, some main problems are discussed deeply including the realization of the B/A/S mode, the work flow of data service site and invalid migration problem which is solved by applying dock service.4. In traditional distributed whole information query system, it is difficult to handle two or more autonomous node at the same time. To solve this problem, a disassemble and query method based on site information slim table is presented in this thesis which can use 'OR' of boolean calculation locally and 'And' of boolean calculation remotely. Ability of parallel process and efficiency is improved and redundant data is reduced.5. After a deep research of communication mechanisms of some kinds of Agent technology, a communication model based on mailbox mechanism is proposed. By separating migration process of Agent and mailbox, routing and transmitting message, the quality of real-time and reliability can be insured, the demand of asynchronously data transmission is meet and the system spending caused by transference of Agent is reduced. |
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