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Database Analysis : Virtual Database Technology Essay

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1. INTRODUCTION

Virtual database technology makes the Internet and other data sources behave as an extension of an RDBMS system. According to some estimates, 85 % of the world 's data is outside of relational database systems. Important data is fling across web sites and database systems. These data sources organize the data sources in different ways, in the vocabulary they use, and in their data-access mechanisms. Writing applications that combine data from these sources is a complex task as heterogeneity is involved.

2.TECHNOLOGY ARCHITECTURE

I.The Virtual Database:

A simple Virtual Database (VDB) run- time view is as shown in Figure 1[1][2]. In this VDB the contents of two bookstores are integrated and a unified schema with two tables, books and reviews is presented. The database application operates on this unified schema, issuing SQL queries through the JDBC or ODBC API; the application is built using standard RAD tools such as Power Builder ,Visual Basic, Delphi, or similar Java toolkits.

The VDB is approached through the VDB Server, and is managed through the browser-based VDB Console. The VDB also consists each external data source, a wrapper that interfaces the data source to the VDB server. A wrapper makes an random external data source, such as a web site, behave like an RDBMS, while the VDB Server merges these separate relational databases into a one single Virtual Database (VDB).

An individual wrapper in action is shown in Figure 2 [2]. The wrapper

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