An Effective Wrapper Architecture to Heterogeneous Data Source

In this paper, we focus on the problem in information integration system of obtaining data from heterogeneous data source accurately and effectively. XML is used as data exchange format of the wrapper. We design the wrapper architecture based on the conversion and management of the views as the bridge from global schema to local schema of various data sources. Our wrapper has two main subsystems, data extract subsystem and query executor subsystem. The former is for loading data for the cache in mediator when changes more than threshold are detected, and the latter is for answering the query from the mediator. The architecture adapts to the data and schema change of the data source and could answer the query of mediator effectively. Considering the wrapper may run in the environment without control, the process in wrapper should be simple enough. The storage in wrapper itself should be as small as possible and the storage of data source could be used. The detail of modules query rewrite, view management, query merge, result wrap and schema change detect are discussed. The behavior of wrapper during the query process in wrapper is discussed with a running example. The security strategy, especial in the distance that the wrapper runs in autonomic data source, is also introduced in this paper.