Joseph Percivall created NIFI-1582:
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Summary: New processor to allow basic data science
Key: NIFI-1582
URL: https://issues.apache.org/jira/browse/NIFI-1582
Project: Apache NiFi
Issue Type: New Feature
Reporter: Joseph Percivall
This idea was sparked by a thread on the user list:
I expect that in the future I’ll need something a little more sophisticated but
for now my problem is very simple:
I want to be able to trigger an alert (only once) when an attribute in an
incoming stream, for instance, goes over a predefined threshold. The Processor
should then trigger (only once again) another trigger when the signal goes back
to normal (below threshold). Basically a RouteByAttribute but with memory.
Thanks
Claudio
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Hello Claudio,
Your use-case actually could leverage a couple of recently added features to
create a really cool open-source processor. The two key features that were
added are State Management and the ability to reference processor specific
variables in expression language. You can take a look at RouteText to see both
in action.
By utilizing both you can create a processor that is configured with multiple
Expression language expressions. There would be dynamic properties which would
accept expression language and then store the evaluated value via state
management. Then there would be a routing property (that supports expression
language) that could simply add an attribute to the flowfile with the evaluated
value which would allow it to be used by flowing processors for routing.
This would allow you to do your use-case where you store the value for the
incoming stream and route differently once you go over a threshold. It could
even allow more complex use-cases. One instance, I believe, would be possible
is to have a running average and standard deviation and route data to different
locations based on it's standard deviation.
You can think of this like an UpdateAttribute with the ability to store and
calculate variables using expression language.
Joe
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