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In NiFi how to write flowfiles into HDFS only if all mandatory files are received?


I am expecting two files, file with abc.txt and file with pqr.txt my next processor should get triggered only if these two files are received.

Currently i am using listFile fetchFIle to capture the changes of source directory. Once i have received two mandatory files my next process is to process them. Now i am not sure how should i configure NiFi to hold the file in queue until i got all mandatory files.

Do we know how should we achieve this using NiFi?


Master Guru



You may want to look in to using the "Wait" and "Notify" processors to accomplish this. The Wait processor would route a FlowFile to the wait relationship (default configuration) until a release signal is written to the cache service by the notify processor. So you route one file to wait and the other to Notify.


Do you know what order the files will always arrive in? If files arrive in no specific order, you may need two wait/notify sets of processors. One flow path has a wait feeding a notify and the other a notify feeding a wait. That will result in a wait occurring on either FlowFile no matter which file is received first.





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@Matt Clarke, thanks for your answer, i am not aware about the file sequences.