Purposes of Enterprise application integration

EAI can be used for different purposes:

Data (information) integration: ensuring that information in multiple systems is kept consistent. This is also known as EII (Enterprise Information Integration).

Process integration: linking business processes across applications.

Vendor independence: extracting business policies or rules from applications and implementing them in the EAI system, so that even if one of the business applications is replaced with a different vendor's application, the business rules do not have to be re-implemented.

Common facade: An EAI system could front-end a cluster of applications, providing a single consistent access interface to these applications and shielding users from having to learn to interact with different applications.

http://en.wikipedia.org/wiki/Enterprise_application_integration