Query And Update Based On XML For Heterogenous Database

The development of computer and network technologies speeds up in recent years.But the data, which are the core of all applications, are still stored in different systems with different manners and live by themselves in distributed and heterogeneous environment. With the steady increase of application requirements, more and more people want to access and manipulate the useful information among multiple massive information sources and achieve the interoperability of multiple computer systems and different information sources. However, these data sources may not only geographically locate at multiple autonomous domains in heterogeneous environment with different data formats, storage modes and access control policies, but also logically differ from each other in data models, manipulation languages and data semantics. Moreover, the sharing ability, modes and contents of the sources may change at any time. So, designing a heterogeneous data source integration mediator system (HDSIMS) supporting the common data model , a uniform query language and update is a better way to implement this type of interoperation. HDSIMS can hide most of the differences of access methods and user interfaces of multiple heterogeneous data management systems. It also provides an information interoperating platform as a common interface to access multiple heterogeneous data sources and combine the intermediate query results from these sources..Combined with the advantage of XML,This paper disscusses some theories and technology of heterogeneous data source integration and presents a heterogeneous data source integration mediator system solving query and update against multi-heterogeneous data sources the basic idea is: we (i) map an XML view query to a set of relational view queries; (ii) map updates over the XML view to updates over the corresponding relational views; and (iii) map query and update over relational views to the underlying relational tables and dispatch them to data sources. The above theoretical principles and prctical techniques are adopt for developing a heterogeneous data source integration mediator system which provides the transparent access to heterogenous data sources such as Oracle, Sybase, DB2.