The Enterprise Information System Tier

Enterprise applications require access to applications running on enterprise information systems. These systems provide the information infrastructure for an enterprise. Examples of enterprise information systems include enterprise resource planning systems, mainframe transaction processing systems, relational database management systems, and other legacy information systems. Enterprises run their businesses using the information stored in these systems; the success of an enterprise critically depends on this information. An enterprise cannot afford to have an application cause inconsistent data or compromise the integrity of data stored in these systems. This leads to a requirement for ensuring transactional access to enterprise information systems from various applications.

The emergence of the e-business model has added another dimension to information system access: enterprises want their information to be accessible over the Web to their partners, suppliers, customers, and employees. Typically enterprises develop Web-enabled applications that access and manage information stored in their information systems. These enterprises can use J2EE^TM applications to extend the reach of their existing information systems and make them accessible over the Web. Enterprises also develop new e-business applications. The sample application described in this book is one example of this class of application.

This added dimension requires an enterprise to ensure secure access to its enterprise information systems because any break in security can compromise critical information. An increase in the number of relationships that an enterprise has to establish with its suppliers, buyers, and partners leads to a requirement that J2EE applications accessing enterprise information systems be scalable and support a large number of clients.

This chapter describes the application programming model for accessing enterprise information system resources from enterprise applications in a secure, transactional, and scalable manner.

In this chapter:

• Enterprise Information System Capabilities and Limitations
• Enterprise Information System Integration Scenarios
• Relational Database Management System Access
• Other Enterprise Information System Access
• Application Component Provider Tasks
• Application Programming Model
• Programming Access to Data and Functions
• Connections
• Security
• J2EE Connector Architecture
• Summary
• Questions and Answers