In jBPM3 there is an ESB Service that hooks up directly to the ESB service. In jBPM4 there isn't such node in the designer or I didn't find it. Will there be an ESB Service node in jBPM4? Is the ESB service usage by JBPM supposed to be done by codding the access to it in a java class or something custom?
There eventually will be. The jBPM side of things is kind of identical to what is in 3, but the ESB side for the async callback needs to change.
For the moment it is indeed something that can/needs to be done in a custom node