How to design asyn flows in Lagom ?
Problem faced:
In our product we have a Lead Aggregate which has a User Id (represents the owner of the lead), Now User has a limitation which says one user can have max of 10 Lead associated with this. We designed this by creating a separate Service ResourceManagement and when a User asks for Picking a Lead, we send a Command to LeadAggregate which generates a Event LeadPickRequested. On ProcessManager Listen to the event and asks for the Resource From ResourceManagement, on Success send Command to LeadAggregate - MarkAsPicked and on this send Push notification to the User that Lead is Picked but from building the UI perspective its very difficult and same cannot be done for exposing our API to third party.
One Sol. we have done is when request is received on Service save a RequestID Vs Request Future . in Command Add the request Id and when the LeadAggregate finally change into Picked State or Picked Failure a PM listen to the event , checks if a RequestFuture is there for the request Id , then complete the future with correct response. This way it works as Sync API for the end User.
Any Better Sol. for this