SAP JRA for SAP Java Applications 
For SAP Java applications, you can use SAP JRA integrated into the Application Server Java (AS Java) instead of the standalone JCo. In this scenario, either communication partner can take on both the client and the server role.
This solution offers you a number of advantages compared to the standalone JCo, without the need for any additional implementation effort.
Prerequisites
Before you can replace SAP JCo with SAP JRA for a Java application, the following condition needs to be met:
Both systems use the SAP Java environment (AS Java)
Advantages
Using SAP JRA for this scenario offers you the following advantages:
Client connections can switch between processes, thus enhancing the robustness of the SAP Java applications.
Server connections can be stateful.
Server connections can use the connection for a callback to the AS application server.
You can configure the SAP JRA centrally in NetWeaver Administrator.
By complying with internal SAP standards, maintainability is enhanced.
Thread- control, security configuration, transaction administration, establishment of connections and synchronization are all managed via the SAP application server and do not require you to make any settings in SAP JRA.
SAP JRA implements Java EE standard interfaces only. Java developers can use a familiar-looking set of interfaces, thus making their work much more straightforward.