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From Andy LoPresto <>
Subject Re: Questions re: customizing a NiFi processor
Date Thu, 14 Dec 2017 03:08:44 GMT

To be honest, I would recommend making those changes directly to the existing PublishAMQP
processor, as unless I am missing something, that does not seem like a breaking change that
would affect other users negatively. I’d suggest opening a Jira for the feature, cloning
the GitHub repository (see the instructions in the Contributor Guide [1]), making the changes
in your branch, building and testing, and then submitting a PR (or patch) for review and inclusion
in the project. This will also require the least amount of code manipulation (example of a
commit from Andre adding EL evaluation to a property descriptor [2]).

If you do not wish to do that, my next recommendation would be to clone the project and create
a new processor in the same Maven module (and add it to the MANIFEST) alongside PublishAMQP
(call it PublishAMQPWithEL or something) and extend the existing PublishAMQP class and override
just the specific behavior you are interested in.

A possible, but in my opinion unnecessary, process would be to add a completely new NAR with
the existing nifi-amqp-bundle/nifi-amqp-processors artifact listed as a dependency and perform
your extension in your own NAR.

Hope this helps.

[1] <>
[2] <>

Andy LoPresto
PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4  BACE 3C6E F65B 2F7D EF69

> On Dec 2, 2017, at 3:43 PM, James McMahon <> wrote:
> Good evening. I am familiar with NiFi and have developed a number of
> workflows using out -of-the-box processors. I now need to develop a custom
> version of PublishAMQP that permits the use of attributes in expression
> language to set specs for the AMQP target.
> I am not very familiar with Maven, but have done some initial research and
> hope I can bootstrap my effort following this link:
> Lacking any experience developing custom processors, I'd like to understand
> how I would establish in my maven project the source code for the existing
> PublishAMQP. I'd like to modify that proven code base to allow the use of
> expression language to set other configuration properties.
> Can anyone help me with an example where source code for an existing
> processor is brought in from a github resource or the like to use as my
> starting point?
> Thank you in advance for any assistance. -Jim

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