Hareesh,
>>I think you can even pick the .csv file as main payload and specify the trigger file as additional file(attachment)
I think that's not gng to work all the time (technically at some instances this scenario will fail)
Let me give u a simple example, if "1.csv" file comes first (which i believe should be the case behind such a design) and PI couldn't able to find attachment "1.trg" then file sender channel will start throwing an error.
And secondly suppose, "1.csv" is there in the source folder and "1.trg" never comes (due to any reason) then channel won't process any other message which comes after "1.csv" until and unless someone manually delete 1.csv from the folder.
Thanks
Amit Srivastava