yes, it would definitely be possible to integrate EJB into another ERP System or a legacy System, but the question would be how. I would look at the following.
1. To check if the ERP provides some kind of API to communicate through
java.
2. if it does not, then the ERP System might have some import / Export functionality of Data ( probably in the form of XML ). then we could use the structure which the ERP System defines and integrate the two systems using Web services (
SOAP) or some proprietory protocols.
Most Ideal would be if the ERP System implements the JCA.
These are the two possible solutions that I can think about..and we did use Webservices (Axis and
Tomcat) for one such integration.