Enterprise SOA

What forces created ESA?

Modern businesses need functionality that is both distributed and centralized. Existing systems of record, such as Enterprise Resources Planning (ERP), Customer Relationship Management (CRM), Supply Chain Management (SCM), and so on, serve the needs of key segments of the organization. But at the same time, a need for many new processes has arisen that requires a flow that moves from one system of record to another, with the context for the process kept outside of any of the existing systems. The traditional way of building enterprise software is not well-suited to these new requirements and does not take full advantage of the new world of pervasive networks, reusable services, and distributed data. Treating an application as a self-contained world no longer meets the needs of business.

In the past, enterprise applications contained the end-to-end processes that were being automated. One program running on one computer automated a workflow process that began and ended inside that application. A single database was the central mechanism of integration. All elements of the stack were contained within one program, as shown in Figure 1-2.

Figure 1-2 actually shows a prettier picture than what exists in many mainframe applications. Even after workflow mechanisms were in use and points of integration were designated, process and integration logic ended up strewn all over the stack and was mixed in with application and UI logic. This structure, however, captures ...