Thanks for explaining, Maurice! I had in fact read the section of the manual you are referring to, but what I really wanted to accomplish was to create a ProcessInstance by a JBoss ESB call, resulting in a (blocking) task for a user. I achieved this by putting the task in a task node directly following the (empty) start state, and using the StartProcessInstanceCommand in the BpmProcessor Action of JBoss ESB (http://docs.redhat.com/docs/en-US/JBoss_Enterprise_SOA_Platform/5/html-single/ESB_Services_Guide/index.html#id5189004).