6

C H A P T E R

Enterprise Application

Integration

E

NTERPRISE

 information systems the collection of relational and legacy data 

base systems, enterprise resource planning (ERP) systems, and mainframe transac 

tion processing systems provide the critical information infrastructure for an

enterprise's business processes. These varied systems hold the information that an

enterprise needs to carry out its daily operations. It is essential that new applications

developed for an enterprise be able to integrate with these enterprise information

systems (EIS).

EIS integration has always been of great importance, and this has given rise to

, or EAI. EAI enables an enterprise to integrate

its existing applications and systems, plus it enables the addition of new technolo 

gies and applications. Enterprises must leverage their existing systems and

resources even as they adopt new technologies. Considering the cost already

invested in these existing systems, no business can afford to discard them. Plus,

since these systems often contain valuable data needed by the enterprise, the

enterprise is not likely to disrupt them. Yet, at the same time, enterprises continu 

ally grow and require new applications. To keep their businesses growing and to

remain cost effective, enterprises must integrate their existing systems with these

new applications and not replace existing systems with new applications written

from scratch. The emergence of Web based architectures and Web services adds

impetus for enterprises to integrate their EISs and expose them to the Web.

The emergence of the Web and Web services is not the only factor driving the

need for integration. More and more, enterprises are either merging or acquiring

other enterprises. Such mergers and acquisitions usually entail merging and com 

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