Resource Adapters
A resource adapter is a system-level software driver that is used by a Java™ application to connect to an enterprise information system (EIS). The resource adapters reside on the application server and provide connectivity between the EIS, the application server, and the enterprise application. Applications deployed on the application server communicate with the resource adapter using the Common Client Interface (CCI). The RAR contains all the information necessary for installing, configuring and running a JCA Resource Adapter; they can be provided by and used by any vendor, provided they comply with the J2EE Java Connector Architecture specification.
Two types of resource adapters are available to you: