This is probably more complicated than what you are looking for, but could you use HTTP site-to-site ? You would send the flow files to an output port and they'd be sitting there until something transferred them from the output port. I'm not sure though if you can get only one flow file at a
I'd like to have a GET rest end point hosted in NiFi that returns the contents of a queued FlowFile. Kind of like if HandleHttpRequest allowed input, and if there was an input, then when it received a GET request it wouldn't create a FlowFile, but instead return the content of the FlowFile.