Using service tasks you can plug in any implementation you want, as long as there is a way to invoke it from Java.
The idea would be to create a domain-specific node that would invoke your spring beans:
- define what parameters you want the user to define in the process
- write and register a handler that invokes your spring bean based on the values provided by the process instance
https://hudson.jboss.org/hudson/job/jBPM5/lastSuccessfulBuild/artifact/target/jbpm-5.0-SNAPSHOT-docs-build/jbpm-docs/html/ch06.html
If you want, I could assist you in writing something like this, so we can add this to the list of domain-specific service nodes we support out-of-the-box?
Regarding process variables, they are stored as part of the process instance state (inside the binary state of the process instance). Pluggable variable persistence can allow you to change this though. What are you trying to achieve?
Kris