How Do J2EE Connectors Work?
To understand how J2EE connectors work, we have to understand the different elements in the J2EE-CA model depicted in Figure 1. The resource adapter is the component that has EIS-specific interface code. For example, the SAP resource adapter will contain code that accesses the SAP through its proprietary BAPI interface. The J2EE-CA also establishes a number of "system-level contracts" between the application server and the resource adapter. These contracts define interoperability between the application server and the application resource adapter.
Basic J2EE Architecture
The Common Client Interface (CCI) provides an RPC-enabled client-side API for accessing the enterprise systems. In other words, if you write business logic components that require application access, you will use CCI to interact with the EIS. In fact, the CCI provides APIs to do the following:
Manage the EIS connectivity (example: getConnection method)
Conduct interactions with EIS
Manage EIS metadata