@Ronald How is replacing the IdentityService useful? The IdentityService is used by the IdentityLoginModule to authenticate users. Conversely, the ExpressionAssignmentHandler invokes ExpressionSession to resolve group memberships. The responsibilities of IdentityService and ExpressionSession overlap to such degree that IdentitySession implements both. For some reason, they currently are separate interfaces. I believe ExpressionSession should be merged into IdentityService and the latter turned into a context service (i. e. a subinterface of org.jbpm.svc.Service) configurable in jbpm.cfg.xml. The reason to subclass ExpressionAssignmentHandler is that it explicitly instantiates IdentitySession in method getExpressionSession(). No other changes were introduced. If ExpressionSession was merged into IdentityService and the latter was an actual context service, then no subclassing would be needed. Is this the kind of cleanup you did? @Tom The facade between the ExpressionAssignmentHandler and the identity component already exists, it is the ExpressionSession. However, one cannot specify a different implementation of the session without subclassing the handler. We need to address this, as well as the overlap with IdentityService. Relationship navigation could also be implemented by returning hand-made proxies just like those generated by Hibernate. However, the navigation requirements imposed on implementors would be made implicit instead of stated explicitly as methods in the facade. I believe explicit is better. Identity components that cannot be exposed as our model are out of scope, but they can always use the existing model as a starting point. Earlier I proposed merging ExpressionSession into IdentityService. On a second thought, the separation between the interfaces also corresponds to the separate requirements of each client of the identity service. Identity implementors could choose to implement only those interfaces that correspond to the features in use. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4137162#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...