Research On Data Integration Technology Of Heterogeneous Database For Digital Forestry

The problem of data integration is a classical problem in database community. With the rise of XML technology, the problem becomes research focus in this community again. With the development of network and rapid increasing of data on the Internet, it is necessary to build a data integration system to share the entire heterogeneous information source. The function of a data integration system is to provide a uniform query interface to heterogeneous data source. Using the interface developers can obtain data information and ignore the problems such as data model heterogeneous, data extracting and data combination, etc. The heterogeneity embodies the different database structure, type and data type mismatch. The extensible markup language (XML) becomes the standard of data exchange for its strong data description capacity and platform-independent characteristics.Combined with the advantage of XML, this paper discusses some theories and technologies of heterogeneous data integrating. In view of the problem, a general data exchange mechanism based on XML documents is proposed and the information exchange problem of the heterogeneous data in relational database of digital forestry technique is solved. The central thought is to access two heterogeneous databases using JDBC and DOM API through XML documents under the JAVA environment. It defines the mapping relation between the resource database and the XML document, and makes the accessing result as DOM object tree. Following, data in the DOM object tree should be converted into XML documents that have same structures with destination database. Using the mechanism, data exchange between SQL server 2000 and Oracle 10g is accomplished.Besides, this paper gives a logical backup method of database, namely, the method of data import and data export. The basis is read the definition of database through the DD of Oracle database firstly, includes schema, table, field, primary key and foreign key and so on, then read the data stored in these tables and write them into corresponding XML document. Through this XML documents database recover can be accomplished.Finally, the security becomes the focus in the storage and transfers of XML documents. In this paper the security standard of XML is introduced, a resolution for DES data encryption regarding the issue is proposed and the security problem of XML is solved in Digital Forestry.The system is generic, flexible, easy to use, portable and extendable. Confirms through experiment, the versatility of the mechanism is stronger and the applicable scope of the mechanism is broader.