The prediction that an EJB can not work as a CORBA client is absolutely wrong. You can use an MDB to receive the message from another process and then use a Java CORBA client to call a remote CORBA server even located in another company. The only requirement is the interoperability of the CORBA ORBs deployed at both sides. A good approach is to use the same ORB at both sides (e.g. standard Java IIOP ORB or same product).
The client ORB .jars have to be deployed in the JBoss lib/ext directory.
I hope this helps for your further design.
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