With the apparition of Wait/Notify processors it is now possible tackle new challenges when it comes to synchronize the execution of different parts of the workflow.
The objective here is the following:
Flow files are sent to a MergeContent processor. Merged flow files are then sent to a processor A while original flow files are sent to a processor B. I want to trigger processor B when and only when processor A has completed.
To use the Wait/Notify approach, a common attribute must be available to be used as a signal in the distributed cache. This JIRA is about adding a processor property allowing a user to add the UUID of the merged flow file as a new attribute of all the original flow files that are constituting the merged flow file.