SAP Java Resource Adapter 
Purpose
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. SAP JRA implements the standard J2EE interfaces for SAP Java Connector (SAP JCo), thus simplifying communication between heterogeneous, distributed J2EE landscapes and SAP.
You can use SAP JRA
to call remote functions in an SAP system by executing 
RFC calls via TCP/IP.
Implementation Considerations
SAP JRA is an add-on for SAP JCo. It is delivered together with the Application Server as a sapjra.rar file. You can find this file in the installation directory.
//<SAPJ2EE Engine Installation>/usr/sap/<System ID>/sys/global/ra/sapjra.rar.
The .rar file contains the Java classes used in SAP JRA.
At present, the J2EE Connector Architecture 1.0 specifications are being implemented. For more information on J2EE and the J2EE Connector Architecture, go to java.sun.com/j2ee.
Restrictions
Incoming communication is not supported by SAP JRA at present.
Additional Information
●
SAP JRA for Client
Applications
●
SAP JRA Development
Guidelines
In Business Intelligence (BI), SAP offers various resource adapters for use with the BI Java SDK. These enable the applications that you develop with the BI Java SDK to communicate with heterogeneous data sources.