Integrating with the Enterprise Information System Tier

by Rahul Sharma and Beth Stearns

This chapter focuses on the integration of enterprise applications with existing enterprise information systems (EIS) and applications. Enterprise information systems provide the information infrastructure critical to the business processes of an enterprise. Examples of EISs include relational databases, enterprise resource planning (ERP) systems, mainframe transaction processing systems, and legacy database systems.

The EIS integration problem has assumed great importance because enterprises are striving to leverage their existing systems and resources while adopting and developing new technologies and architectures. Today, enterprise application development is more about integration rather than developing an enterprise application from scratch. Enterprises cannot afford to discard their existing investments in existing applications and EISs. The emergence of Web-based architectures and Web services has made it more imperative for enterprises to integrate their EISs and applications and expose them to the Web.

The EIS integration problem is one part of the broader scope of enterprise application integration (EAI). EAI entails integrating applications and enterprise data sources so that they can easily share business processes and data. This chapter focuses on the following aspects of EAI, and includes discussions of recommended guidelines:

• Application integration--Existing enterprise applications may be off-the-shelf bundled applications or they may be developed in-house. Two examples are supply chain management (SCM) and customer relationship management (CRM) applications. While such applications expose business level functionality used directly by end users or integrated with other enterprise applications, they usually do not expose the underlying data on which the business functionality is built.
• Data integration--An enterprise environment often contains more than one database system upon which its business processes run. These database systems may be relational, object-based, hierarchical, file based, or legacy stores. Data integration focuses on integrating existing data with enterprise applications. For example, an integration might entail integrating a Web-based order management system with an existing order and customer database.
• Legacy integration--Legacy integration involves integrating new enterprise applications with applications and EISs that have been in operation for some time, often referred to as an enterprise's "legacy" systems. An enterprise cannot afford any disruption in these legacy systems. This chapter focuses on how to connect enterprise applications to these legacy systems.