NIFI-13554 GetSlackReaction processor to fetch reactions for Slack message

[krisztina-zsihovszki]

Summary

NIFI-13554

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  • JDK 21

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[mattyb149]

Should we require input to be in JSON format? It might be more flexible (and facilitate a future ConsumeSlackRecord processor for example) to use Record Path and a Record Reader?

[exceptionfactory]

I'm a bit concerned about the use of JSON Paths for several properties. If the input format is from other Processors, then making this configurable seems unnecessary.

Beyond that point, I'm more concerned about the scalability of this the check and wait strategy. The idea of the wait period property seems like it could easily lead to FlowFiles backed up in a queue, waiting for reactions that may never arrive. This presents some fundamental flow design concerns. I understand that retrieving reactions is separate from messages themselves, however, it seems that a more scalable approach would require either changes to ConsumeSlack, or a new ConsumeSlackReactions Processor. A feed of reactions allows for eventual merging with messages, as opposed to a Processor designed to loop and wait with a large number of polling requests.