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NiFi Custom Controller Service Implementation Setup

New Contributor

I am trying to write an alternate implementation of the AtomicDistributedMapCacheClient<R> service. Specifically this is so that the "DistributedMapCacheLookupService" can use my implementation.

So far I have the class implementing the interface like so:

public class CustomDistributedMapCacheClientService extends AbstractControllerService implements AtomicDistributedMapCacheClient<Long> {

And I have a pom that generates the service-nar that looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="" xmlns:xsi=""


	<!-- My Custom Java Code -->
	<!-- Add dependency to service api nar to make my implementation available on the classloaders. -->



I set nifi-standard-services-api-nar as a dependency so that the classloaders will be configured properly. This lets me select my custom service in the DistributedMapCacheLookupService. However, it is showing this error in the UI:

... nifi.service.custom.nar is not compatible with DistributedMapCacheClient ...

I traced this message to this function: which returns false. Probably due to the classloading not being setup due to a problem with my pom.xml dependencies. Or I'm implementing the wrong class.

Is it possible to generate a custom service nar that adds an alternative implementation of the DistributedMapCacheClient service to be used by the DistributedMapCacheLookupService? Is there a template project I can refer to in order to set this up properly?

I have read through the Developer Guide on this a couple times: but unfortunately am still confused as to how this works (an example project would help me a lot).




New Contributor

Did you ever find a solution to this? I have the exact same problem.

Community Manager

@chubbs As this thread is older, you would likely be better served by creating a new thread. This would also provide an opportunity to provide further details on your situation, steps taken so far and any errors encountered. 

Cy Jervis, Manager, Community Program
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