Update:
I realised that I can import the files from the jbpm-binaries.zip archive to use the jbpm api in my own eclipse version. By doing so, I was able to provide a complete workflow as web service. The problem is that this workflow only contains of 2 self-developed work items with corresponding handlers. How can I integrate human tasks now without using the demo setup?
My impression is that I have to use the web console to complete human tasks or is there another way?