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From Mark Petronic <>
Subject Re: Nifi startup error after I install my first custom processor
Date Fri, 20 Nov 2015 06:26:30 GMT
Thanks so much Bryan. It is running now. It is starting to come together
but I'm still a little unclear on when to include nifi files to pick up
dependencies and when to directly include the upstream dependencies. Like
say some nifi nar like nifi-processor-utils already has a dependency on
commons-lang3 and my custom processor needs commons-lang3, should I satisfy
that by depending on nifi-processor-utils (which in know will already be in
the install) or should I add a dependency on commons-lang3 in my nar and
duplicate the libraries? I realize that there are version issues to be
concerned with which I believe is the genesis for nars to start with but
assume I need the same version, too? What't the general best practice there?

Also, now that I was able to run my processor, I have a question about
logging. I see that the processors use getLogger() to get a logger. But is
see in other places a more traditional use of LoggerFactory.getLogger().
What is the best approach to logging from helper classes that I use in my
processor that are not inner classes of the processor class by defined
outside in separate class files because I intend to reuse them across
multiple processor types? I need to debug an error that I am seeing in one
of those helper classes and need to add some logging.


On Thu, Nov 19, 2015 at 8:23 PM, Bryan Bende <> wrote:

> Hi Mark,
> Glad to hear you were able to get started building processors, and glad
> that blog post helped!
> I pulled down your code and built and deployed it. It looks like the issue
> is that your processors pom has a dependency on:
> <dependency>
> <groupId>org.apache.nifi</groupId>
> <artifactId>nifi-standard-processors</artifactId>
> <version>0.4.0-SNAPSHOT</version>
> </dependency>
> Which means your NAR ends up having the standard processors jar in it, but
> they are also deployed in nifi-standard-nar which causes some problems. You
> can see the jar is there by looking
> in
> work/nar/extensions/nifi-bigdata-nar-1.0.nar-unpacked/META-INF/bundled-dependencies/.
> I removed that dependency from the pom and it looked like the only
> compilation errors were on some missing json related libraries (jackson and
> json path). I added these to your processor pom and it seems to deploy now:
> <dependency>
>     <groupId>com.jayway.jsonpath</groupId>
>     <artifactId>json-path</artifactId>
>     <version>2.0.0</version>
> </dependency>
> <dependency>
>     <groupId>org.codehaus.jackson</groupId>
>     <artifactId>jackson-mapper-asl</artifactId>
>     <version>1.9.13</version>
> </dependency>
> Hope that helps. Let us know if you have any other questions!
> -Bryan
> On Thu, Nov 19, 2015 at 7:53 PM, Mark Petronic <>
> wrote:
> > Well, I finally built my first processor. Was a nice experience. Nice
> APIs!
> > This was my first work with Maven and Nifi so, if things look
> > wrong/strange, please go easy on me. :) The issue is when I copy the NAR
> > file in the lib directory and restart Nifi, it does not start up. I tried
> > removing the work directory for a clean start, no joy. If I remove my
> NAR,
> > works fine. Wondering if one of you experts would not mind helping me
> over
> > this hump because I have no clue what is happening based on the error
> > message in the log. Seems like some other processor, DetectDuplicate, is
> > failing to startup when mine is in there?? I pasted the startup log
> traces
> > here: My processor code is here:
> > I would be very
> > grateful for any guidance. It seems like a pretty simple processor so I
> was
> > surprised this happened. The code is commented so hope that helps you
> > easily understand what is going on there. Oh, I started from this very
> > helpful post (thanks Bryan):
> >
> >
> > .
> > I am running a build of Nifi from the GitHub mirror,
> > commit 90f6830003b76204e25dec9fafec2488c8bda550.
> >
> > Thanks,
> > Mark
> >

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