there is no need to inform task client about the callback implementation. It is only relevant to the task service side. Not sure how do you use task service but there are several ways of doing that:
- using web application - from 5.3 there is a human task web application that exposes ht features of hornetq by default, it is configurable via web.xml and its init parameters
- programatically - UserGroupCallbackManager is responsible for callback registration
- using system properties - use -Djbpm.usergroup.callback=[your custom callback class name] - note that your class must have default constructor
- using property file - use simple property file that will hold a single line (or more depending on callback implementation) to bootstrap it when callback manager is initiated
- file name: jbpm.usergroup.callback.properties
- property name: jbpm.usergroup.callback=your custom class name
- location: org/jbpm/task/identity/ on your classpath
HTH