Agent In Distributed Active Database Applications

Database technology is one of the fastest developing and widely used technologies in computer science area. While it is being applied in more and more fields, it becomes almost impossible for traditional database technology to deal with the new presented requirements. Active database (ADB) integrates active capabilities with traditional databases and provides active services for its clients. Distributed database (DDB) is another kind of system in which the data are distributed over networks but logically belong to a single data set. By combining the technologies of ADB and DDB, we can get a new type of system the data of which are geographically distributed but logically unified, and are able to provide active services. Such a database system can well address many issues which are difficult to be solved by traditional database technology, in such fields as in computer supported cooperative work, engineering design and manufacture, office automation and decision supported systems.Presently, there are three ways to implement an ADB. The first one is to modify, i.e., to add an event monitor and a rule base to a legacy database. The second one is to embed an active programming language. The last one is to redesign the whole ADB programming language. None of the above ways is perfect and can satisfy the needs of distributed circumstances. Therefore, we put forward the view of combining the agent technology and traditional database: utilizing the agent's apperception, reactivity, distribution and intelligence to make traditional database active and adapted to distributed circumstance. It can not only make up the defects of ADB, but also can strengthen the overall system functionality. Some special functions, such as real-time response collaboration support can be realized using agent.The work of my dissertation includes:1. Analyzed the features and the state of art of the distributed active database (DADB) and point out the deficiencies of traditional DADB. Put forward the thought of optimizing the DADB system with the agenttechnology. Summarized the design techniques of both single agent and agent group.2. Applied the agent technology into ECA rules, and Proposed the ECA agent, which can be integrated with any database, providing active capabilities and applicable to distributed circumstances.3. Implemented the preliminary version of a computer supported cooperative design system, which is based on ECA Agent, and presented the solutions for some key problems using ECA agent.Compared with the existing work, the main innovation of this dissertation is the combination of agent technology with database to build a DADB, the application of the agent technology in ECA, the design of ECA agent and the way to use ECA agent in real software development.The remaining text is arranged as follows: In chapter one, we summarize the features of distributed database and its application. In chapter two, we set forth agent in the distributed application and point out the defects of traditional DADB along with the necessity of using agent. In chapter three, we present the view of using single agent and agent group. In chapter four, we propose the idea of ECA agent and its key design technologies. In chapter five, we analyze the implementation of a CSCDS based on ECA agent. We make the conclusion in the last part of this paper.