EAI levels

We can differentiate three EAI levels. This is an important aspect of the IBM business integration strategy. The strategy positions the WebSphere Business Integration family of products in three tiers:

The lowest level of EAI is sending information directly from one application to another, for example, using WebSphere MQ messaging. This is known as point-to-point application integration architecture. Logic and formatting for data exchange is totally within the applications.
Where there are many applications involved, information needs to be intelligently routed to where it is needed. It might have to be transformed or reformatted, for example, using WebSphere Message Broker or WebSphere Process Server. The connected applications do not need to know about required data formats, but the business logic that starts the exchange is still inside the calling application. This represents the hub-and-spoke application integration architecture.
At the highest level of integration, a business process is represented by applications started by specific business conditions (or business logic). Here, the process is controlled by a workflow manager, such as WebSphere MQ Workflow, and supports sophisticated multistep process flows. WebSphere MQ Workflow also works with applications, while allowing human intervention. There is no need for the applications to know anything about the overall business process, which is defined in a business process model. The business process, controlled and executed by a workflow manager, knows when each application has to be invoked and what data is required. The applications do not link to each other. They send results back to a workflow manager. Then the workflow manager uses the business process definition to decide what happens next.