Distributed Heterogeneous Data Integration Based On OGSA-DAI

Along with the development of the Internet and Grid, many applications find the needed data at different locations. The data are heterogeneous, not only the way of data storage, also the style of information expressed. It needs to effectively integrate the distributed heterogeneous data for developing applications. Based on these data a variety of applications have been developed, so integration of the data should not affect the existing system. Data Integration is aimed at achieving the effective integration of distributed heterogeneous data and providing transparently data access. The data providers hope for data easily provided, and ensuring the safety of their own data sources. Data users can transparently access the needed data without knowing too much detail.According to the characteristics and requirements of distributed heterogeneous data integration, this paper designs and implements a data integration middleware based on OGSA-DAI. It meets all the requirements and achieves an effective integration of heterogeneous data. This paper analyzes the heterogeneity of data and the role in integration, and data integrated model. Data Service is designed to hide the heterogeneous data sources. On the basis of specifying the criteria of information description, by the way of mapping solve the data heterogeneity on information expressed. According to the information described standards, map the data to a virtual table. Users query the virtual data through data service. This paper presents a simplified SQL named SIM-SQL to query relational database and XML database. When really need to visit the data source, SIM-SQL should be transformed into SQL or XPath. The transformation algorithm is presented in this paper. Meanwhile, the data obtained from the data source and the format is also changed according to the information mapping. Data services have standard Web Service interface, thus realizing the information hiding and transparency visiting for data sources. This paper also presents a data service development and deployment tool and explains how to use this tool for encapsulating data source. The paper also introduces an information distribution center. It realizes establishing and publishing the criteria of information description. It also has the function of classification, registration, discovery and management for data services. Finally, the design and realization of data integration center is provided. The data integration center effectively integrates distributed heterogeneous data using data services and provides the integration and transparency visit of distributed heterogeneous data.