I mean, is it possible to use seam in a back-end application that just offers functionality through remote EJBs or Webservices or MDBs or whatever? (ant therefore there is no http session or request).
Does it make sense to use Seam in such scenario?
If so, how is it launched? Since in a web context a listener is declared in the file “web.xml”, in the described scenario, where is Seam launched?
No, SEAM is JSP-based, which requires a servlet/JSP engine and a web container. It’s neither possible nor desirable.
Creating a service-based back end that’s independent of user interface is indeed a very good idea. You can use EJBs or Hibernate to accomplish that. But you don’t need SEAM.