Major Description
One of the JAX-RS 1.1 requirements is to support EJB[1]:
"In a product that also supports EJB, an implementation MUST support use of stateless and singleton session beans as root resource classes, providers and Application subclasses in a Web application. JAX-RS annotations MAY be applied to a bean's local interface or directly to a no-interface bean. If an ExceptionMapper for a EJBException or subclass is not included with an application then Exceptions thrown by an EJB resource class or provider method MUST be treated as EJB application exceptions: the embedded cause of the EJBException MUST be unwrapped and processed as described in section 3.3.4."
[1] http://jcp.org/aboutJava/communityprocess/maintenance/jsr311/311changelog.1.1.html