We're using JMS with a third-party RAR. In one ear we're using inbound JMS with message driven beans, in another we're using outbound JMS with servlets. We currently don't have the messaging subsystem enabled as we don't use HornetQ. However now javax.jms.api does no longer the added as an implicit dependency to our deployments and we therefore get NoClassDefFoundError on JMS classes. Should we rather enable the messaging subsystem or add javax.jms.api "manually" using either jboss-deployment-structure.xml or the Dependencies manifest header?