Given the two fundamental constructs of sequences and parallelism, the natural evolution is to combine both aspects to support:
- Sequences in their own right within parent & sub-tickets
- Further parallelism on parent and/or sub-tickets
- Gathering all back into the parent ticket
- Deliberate orphaning of sub-tickets
Instead of single activity synchronous parallelism, one or both of the tickets can use sequences in their own right i.e. both tickets can asynchronously progress, until such point that they are required to join back together. As per the simple parallel example, the sub-ticket(s) will need to be solved to unblock the parent ticket from progressing past the join.
Its also possible to, in effect, nest parallelism where more complex workflow process requires this.
Typically, all parallel tickets are gathered back into parent ticket, as represented by green activities, and as opposed by purple activities. However, it is possible to not join back parallel activities. An example may be a separate follow-up action where the parent ticket is allowed to progress to solved.