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From rishabprasad005 <>
Subject Re: How can I pass a flowfile attribute to a controller service?
Date Mon, 23 Apr 2018 11:29:11 GMT

Thanks for the reply. From the above replies I understand that the flowfile
attributes were not available by the DBCPConnectionPool service because the
expression langugage used by me were evaluated at the time of service
enable. Thus, the service is starting before any other processor used in the
flow and at the time of service enable the file containing the properties
has not been read by the GetFile processor, and hence the expression
language doesn't even have the content to extract from.

So basically, the connection to the database is being established even
before the processors have started to run. So my question here is, why does
Nifi establishes the connection even before any other processor starts
running. Also, is there a way where we can postpone the evaluation of
expression language used til the processor starts running? If we can do
that, we can certainly make the flowfile attributes available to the
controller service. Ultimately, I am looking for a way where we can make the
flowfile attributes available to the controller services. (I know we can
achieve that using 'variable.registry' but every time their is change in the
file, it requires a restart. I need to avoid the restart) 

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