SAP Java Resource Adapter 
Purpose
The SAP Java Resource Adapter (SAP JRA) is a J2EE -compatible connector for SAP systems. It enables the integration of SAP systems with J2EE application servers. The SAP JRA implements the standard J2EE interfaces for the SAP Java Connector (SAP JCo), thus simplifying communication between heterogeneous, distributed J2EE landscapes and SAP.
You can use the SAP JRA to call remote functions of an SAP system by executing RFC calls via TCP/IP.
Implementation Considerations
The SAP JRA is an add-on for the SAP JCo. If you use the SAP Web AS, the SAP JRA is installed automatically with the SAP JCo. It is also possible to install the SAP JRA as a standalone component from the Internet (service.sap.com/connectors).
SAP JRA is supplied as the file sapjra.rar, which is implemented on the application server. The .rar file contains the Java classes and their user documentation.
The J2EE Connector Architecture specifications 1.0 are currently implemented. For more information on J2EE and the J2EE Connector Architecture, go to java.sun.com/j2ee.
Constraints
The SAP JRA does not support inbound communication, tRFC, IDocs, or certificates .
Further Information
In the Business Intelligence (BI) area, SAP offers various resource adapters that can be used with the BI Java SDK. These enable the applications that you develop with the BI Java SDK to communicate with heterogeneous data sources.
· BI Java Connectors