This book addresses issues related to managing data across a distributed database system. It is unique because it covers traditional database theory and current research, explaining the difficulties in providing a unified user interface and global data dictionary. The book gives implementers guidance on hiding discrepancies across systems and creating the illusion of a single repository for users. It also includes three sample frameworks—implemented using J2SE with JMS, J2EE, and Microsoft .Net—that readers can use to learn how to implement a distributed database management system. IT and development groups and computer sciences/software engineering graduates will find this guide invaluable.

A centralized database management system (DBMS) is a complex software program that allows an enterprise to control its data on a single machine. In the past two decades, there have been many mergers and acquisitions, which have resulted in organizations owning more than one DBMS. Not all of these systems came from the same vendor. For example, it is common for an enterprise to own a mainframe database that is controlled by IBM DB2 and a few other smaller workgroup (or departmental) databases controlled by Oracle, Microsoft SQL Server, Sybase, or other vendors. Most of the time, users need to access their own workgroup database. Yet, sometimes, users need to access data in some other workgroup’s database, or even in the larger, enterprise-level database.

The need to share data that is dispersed across an enterprise cannot be satisfied by centralized DBMS software. To address this requirement, a new breed of software to manage dispersed (or distributed data) called a distributed database management system (DDBMS) is required.

A DDBMS maintains and manages data across multiple computers. A DDBMS can be thought of as a collection of multiple, separate DBMSs, each running on a separate computer, and utilizing some communication facility to coordinate their activities in providing shared access to the enterprise data. The fact that data is dispersed across different computers and controlled by different DBMS products is completely hidden from the users. Users of such a system will access and use data as if the data were locally available and controlled by a single DBMS.

This book addresses the issues in design and development of a DDBMS. In the chapters that follow we will address the issues involved in developing such a system and outline different approaches for solving these problems. We will also present two Java-based frameworks and one Microsoft .NET-based framework that provide the underlying structure needed to develop a DDBMS.