Design And Implementation On Multi-Database Query Middleware

With the development of informationization, data storage of enterprises rose fast. Diversity has become a current feature especially for the Un-Structured data and the semi-structured data. It formed a large number of self-distributed and heterogeneous data sources in the process of building information society. It's constraint because data sources can't share resources each other. Data source re-composition bring huge risk and high cost. So how to realize resources integration between existing data sources has been an urgent issue in the process of enterprises informatization.Multi-database System can construct a cooperative database system in the pre-existing, distributed, heterogeneous, autonomous file and database System. Multi-database system through schema mapping with local data source can make a global, distributed coordination system to support the physical distribution of multiple data sources transparent and global access without affecting the autonomous basis.The paper presents a multi-database middleware base on XIDM common data type and service-oriented framework. It implements a series of functions including schema mapping, global query and query optimization etc. The paper done the following works:First, based on the domestic and international multi-database query technology research background, the paper introduced the multi-database, middleware and other related technologies, then compared some common data types in multi-database system, researches the schema mapping, realizes the objected generation algorithm.Second, the paper compares and analysis some common query languages used in multi-database, and design the query language according to requirements. Realize the query decomposition algorithm. Multi-query optimization to the problem of data analysis, the query cost estimate based on the objective inquiry of this article, using a multiple regression algorithm based on the dynamic optimization strategy to achieve a post-processing on a global query optimization scheduling.Finally, The Paper design the middleware architecture base on SOA and.Net development environment, then completed major development works under the architecture, at last, summing up deficiencies which need to be improved in middleware.