We started our discussion of integration patterns in the preceding two chapters. We considered several architectural patterns to support Enterprise Application Integration. In this chapter, we'll discuss architectural patterns for Enterprise Information Integration (EII).
The purpose of EII is to make data originated in one system available in other systems. The reasons for it may be as follows:
To process original data with a different set of tools to achieve a new result; for example, taking data from HR and accounting systems to print paychecks.
To create a copy of the original data in order to offload the system while performing noncritical operations. A typical example would be creating daily reports for a system with a heavy load, such as a banking system.
To combine data originated in several systems to query or to analyze aggregated data. The data sources can be heterogeneous and distributed over several locations.
To retrieve data from different sources...