Even driven is also very useful (or rather the only solution), in some cases. For example in our case, we have a sequence of HTTP calls that result in multiple flow files, each flow file is collected and also forks into a separate flow to create a new flow file. This kind of works like a linked list. So what we gotta do is merge all of these individual flow files into a single archive at the end using the MergeContent processor. This must only happen when we've collected all the flow files, we don't really know the number of flow files we may be getting until the last flow file is collected. So the MergeContent processor should only be triggered when all the flow files are collected, not before that. While the Timer based and CRON based triggers do not have such a provisioning. We tried to solve this issue with Wait and Notify but apparently, there is no way to block the MergeContent Processor from being triggered until the last flow file has been queued to the MergeContent processor. As flow file transfer and queuing to the MergeContent processor in large number of files say 200,000 files itself takes some time, and it is possible that the MergeContent processor gets triggered halfway through the queuing. ... View more