Question

Can someone post examples of common design patterns with sample implementation twx?

Answer 1

Common design patterns in IBM BPM / BAW with a sketch of each implementation (several are detailed in other answers on this site):

1. Facade service per system - one toolkit service flow per external operation ("CRM: get customer"), input / output as business objects, errors normalised; BPDs never call an integration directly. Implementation: toolkit "CRM Connector" with a Server definition, external service, wrapper flows.
2. Claim check - references instead of payloads in the process (question 2572).
3. Constructor / initializer - first activity builds the complete business object (defaults, lookups).
4. Configuration by EPV - thresholds and switches as EPVs read through one helper (question 766).
5. Delayed response / request-callback - asynchronous integration with a message event and a timer escalation (question 1025).
6. Correlated message events - UCA + intermediate message event with a business key (question 2573).
7. Timer escalation ladder - timer boundary events on a user task: reminder at 2 days, reassign to manager at 5, auto-decision at 10; each timer path returns to the task via a gateway.
8. Exception queue - errors caught by boundary events create a "Handle exception" task for an operations team with Retry / Skip / Abort decisions (question 2554).
9. Saga / compensation - after a failed step, run compensating services in reverse order (a script keeps a list of completed steps; an event sub-process runs the compensations).
10. Multi-instance work - "for each line item" sub-process with a completion condition, instead of loops with counters.
11. Four-eyes approval - second approver must differ from the first: team filter service excluding tw.local.firstApprover.
12. Dashboard + Service Call - CSHS dashboards that read through service flows, never SQL in the coach.
13. Audit trail service - one toolkit service writes who / what / when to a table or the instance's comments; called from key activities.

// four-eyes: team filter service (input team TWTeam, output TWTeam) used by the "Second approval" activity
var out = new tw.object.Team(); out.name = tw.local.team.name; out.members = new tw.object.listOf.String();
for (var i = 0; i < tw.local.team.members.listLength; i++) {
  if (tw.local.team.members[i] != tw.local.firstApprover) out.members.insertIntoList(out.members.listLength, tw.local.team.members[i]);
}
tw.local.filteredTeam = out;

References

• BAW documentation - modeling processes (events, gateways, teams, error handling)