Hello, Have you been able to find a way to extend the standard processors?
I was wondering what would be the proper way to do that. So I tested few things: 1. Create new custom nar which depends on nifi-standard-processors First, I tried to add new nar bundle, let's say "nifi-stdpllus-bundle" following "Maven Projects for Extensions" [1]. Then add a dependency to nifi-standard-processors so that I can write a processor extends MergeContent. When I compiled it and tried to start NiFi, I got the exact same error that you reported [2]. It indicates that the newly added custom nar "nifi-stdplus-bundle" made NiFi to load standard processors such as DetectDuplicate from nifi-stdplus-bundle class loader, because the custom nar has nifi-standard-processors.jar in it. DetectDuplicate uses org/apache/nifi/distributed/cache/client/Serializer, which resides in another jar, nifi-distributed-cache-client-service-api.jar, which is not contained in the custom jar. I assume you were in this situation. 2. Add nar reference from custom nar to standard nar The reason why nifi-standard-processors can use nifi-distributed-cache-client-service-api.jar is that nifi-standard-nar has nar reference to nifi-standard-services-api-nar (which has Serializer) in its pom. So, I added the same nar dependency in 'nifi-stdplus-bundle/pom.xml'. Then NiFi started to launch without the previous error. However, since standard processors are in two nars (standard and custom), NiFi shows warning messages [3], and also it increases file size. 3. Specify 'provided' scope In order to avoid having standard processors in the custom nar file, I used 'provided' scope for the nifi-standard-processors dependency in nifi-stdplus-processors. Please check this commit as an example [4]. Hope this helps. BTW, I'm interested in why you had to extend MergeContent processor in the first place. Would you elaborate what was the shortcomings? I wonder if it can be merged into the project. Having required change in master branch is the best way to extend (enhance) a standard processor :) [1] https://cwiki.apache.org/confluence/display/NIFI/Maven+Projects+for+Extensions [2] 2016-09-12 11:07:46,861 ERROR [main] org.apache.nifi.NiFi Failure to launch NiFi due to java.util.ServiceConfigurationError: org.apache.nifi.processor.Processor: Provider org.apache.nifi.processors.standard.DetectDuplicate could not be instantiated java.util.ServiceConfigurationError: org.apache.nifi.processor.Processor: Provider org.apache.nifi.processors.standard.DetectDuplicate could not be instantiated [3] 2016-09-12 12:00:43,981 WARN [main] org.apache.nifi.nar.ExtensionManager Attempt was made to load org.apache.nifi.processors.standard.AttributesToJSON from org.apache.nifi.nar.NarClassLoader[./work/nar/extensions/nifi-standard-nar-0.7.0.nar-unpacked] but that class name is already loaded/registered from org.apache.nifi.nar.NarClassLoader[./work/nar/extensions/nifi-stdplus-nar-0.7.0.nar-unpacked]. This may cause unpredictable behavior. Order of NARs is not guaranteed. [4] https://github.com/ijokarumawak/nifi/commit/134ff5dfc144abe463630ec9d4ab332bd16f22ac Thanks, Koji On Fri, Sep 9, 2016 at 11:25 PM, bsabin <bobocsa...@gmail.com> wrote: > Hi, > > I have a custom processor that extends the MergeContent proc and when NiFi > starts I have this error in logs: > > 2016-09-09 18:17:00,607 ERROR [main] org.apache.nifi.NiFi Failure to launch > NiFi due to java.util.ServiceConfigurationError: > org.apache.nifi.processor.Processor: Provider > org.apache.nifi.processors.standard.DetectDuplicate could not be > instantiated > java.util.ServiceConfigurationError: org.apache.nifi.processor.Processor: > Provider org.apache.nifi.processors.standard.DetectDuplicate could not be > instantiated > at java.util.ServiceLoader.fail(ServiceLoader.java:232) > ~[na:1.8.0_101] > at java.util.ServiceLoader.access$100(ServiceLoader.java:185) > ~[na:1.8.0_101] > at > java.util.ServiceLoader$LazyIterator.nextService(ServiceLoader.java:384) > ~[na:1.8.0_101] > at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:404) > ~[na:1.8.0_101] > at java.util.ServiceLoader$1.next(ServiceLoader.java:480) > ~[na:1.8.0_101] > at > org.apache.nifi.nar.ExtensionManager.loadExtensions(ExtensionManager.java:107) > ~[nifi-nar-utils-1.0.0.jar:1.0.0] > at > org.apache.nifi.nar.ExtensionManager.discoverExtensions(ExtensionManager.java:88) > ~[nifi-nar-utils-1.0.0.jar:1.0.0] > at org.apache.nifi.NiFi.<init>(NiFi.java:135) > ~[nifi-runtime-1.0.0.jar:1.0.0] > at org.apache.nifi.NiFi.main(NiFi.java:243) > ~[nifi-runtime-1.0.0.jar:1.0.0] > Caused by: java.lang.NoClassDefFoundError: > org/apache/nifi/distributed/cache/client/Serializer > at java.lang.Class.getDeclaredConstructors0(Native Method) > ~[na:1.8.0_101] > at java.lang.Class.privateGetDeclaredConstructors(Class.java:2671) > ~[na:1.8.0_101] > at java.lang.Class.getConstructor0(Class.java:3075) ~[na:1.8.0_101] > at java.lang.Class.newInstance(Class.java:412) ~[na:1.8.0_101] > at > java.util.ServiceLoader$LazyIterator.nextService(ServiceLoader.java:380) > ~[na:1.8.0_101] > ... 6 common frames omitted > Caused by: java.lang.ClassNotFoundException: > org.apache.nifi.distributed.cache.client.Serializer > at java.net.URLClassLoader.findClass(URLClassLoader.java:381) > ~[na:1.8.0_101] > at java.lang.ClassLoader.loadClass(ClassLoader.java:424) > ~[na:1.8.0_101] > at java.lang.ClassLoader.loadClass(ClassLoader.java:357) > ~[na:1.8.0_101] > > > On Nifi 0.6.1/ 0.7.0 it worked, but when I've tried to use PutSQL proc, I > could not see in the property list the Controller Service populated. > Is there a proper way to extend the behaviour of a standard processor ? > > Thanks > > > > -- > View this message in context: > http://apache-nifi-developer-list.39713.n7.nabble.com/nifi-1-0-extending-a-standard-processor-tp13306.html > Sent from the Apache NiFi Developer List mailing list archive at Nabble.com.
