We need to reflect SLA constraints between different tasks into a given Activiti process. SLA clauses are mainly time based. (eg attached image)
Can we consider already the event listeners? Do we have a certain wait state concept implemented in Activiti? Would you please assist on how to implement these requirements?
There is a concept of a Process Event Bus (PEB) as part of the Process Virtual Machine (PVM) which you register your SLA component and listen to the appropriate events being fired to calculate the SLA constraints. We're still in the design and decision process, please consider http://jira.codehaus.org/browse/ACT-28 if you want to be posted on the decisions.
So as a result, also we will have a complete solution for the sub-process calling issue with wait state. For instance, a task may launch another workflow. The latter should notify the calling task when it is completed!