Hi!
I think the Jbpm5 Mina server will not accept conections outsided 127.0.0.1. If you check the class
https://github.com/droolsjbpm/jbpm/blob/master/jbpm-human-task/src/main/java/org/jbpm/task/service/mina/BaseMinaTaskServer.java
The start() method configures the local interface used:
acceptor.bind( new InetSocketAddress( "127.0.0.1", port ) );
and this "127.0.0.1" will only accept local conections.
If we want to let clients from outside, this parameter should be configurable.