NoClassDefFoundError custom controller using external jars

Constan — Tue, 01 Sep 2020 12:48:12 GMT

Hi,

I am running into a problem with deploying a custom controller service to NiFi (I am using the latest version of NIfi 1.12 as of writing this). Now what I am trying to do is to create a custom controller service that would allow me to access a Virtuoso DB instance (similarly to DBCPConnectionPool). This controller relies on 2 external jar files (provided by Virtuoso) that I have placed inside a /libs folder under the module that implements the interface of my service. I have pointed to these jars as dependencies in the pom.xml of that same module and maven is able to import them. Furthermore, I am able to successfully compile and run a JUnit test of my implementation of the service which consists of simply getting a connection and checking if it is open.

The problem arises when I compile my service into a NAR and then deploy that service in NiFi. NiFi is able to detect it but when I try to enable it, it throws a NoClassDefFoundError that is related to these external jars. Now I am considering doing similarly to DBCPConnectionPool and create a property to point to these jars and load them externally, however, I simply do not understand what is causing the problem and I am too curious to let it go, I am also concerned that this approach may not be viable for these jars. So i am curious if someone can point me in the right way.
Here is my folder structure:

Here is the code I am trying to execute @OnEnabled. which passes JUnit

@OnEnabled public void onEnabled(final ConfigurationContext context) { getLogger().info("Initializing Virtuoso Repository"); try { ConnectionPoolDataSource dataSource = new VirtuosoConnectionPoolDataSource(); ((VirtuosoConnectionPoolDataSource)dataSource).setCharset(context.getProperty(REPOSITORY_CHARSET).getValue()); ((VirtuosoConnectionPoolDataSource)dataSource).setServerName(context.getProperty(REPOSITORY_SERVER).getValue()); ((VirtuosoConnectionPoolDataSource)dataSource).setInitialPoolSize(Integer.parseInt(context.getProperty(REPOSITORY_CONNECTIONPOOLSIZE).getValue())); ((VirtuosoConnectionPoolDataSource)dataSource).setMaxPoolSize(Integer.parseInt(context.getProperty(REPOSITORY_MAXCONNECTIONPOOLSIZE).getValue())); repository = new VirtuosoRepository(dataSource, context.getProperty(REPOSITORY_DEFAULTGRAPH).getValue(), true); repository.initialize(); }catch (Exception e){ getLogger().error("Unable to Initialize Virtuoso Repository", e); } }

Here is the pom where/how I declare the jar dependencies (This is where I am assuming the error might be)

And this is the log of the error I am getting when I try to enable it from NiFi:

2020-08-31 13:50:03,567 ERROR [Timer-Driven Process Thread-4] o.a.n.c.s.StandardControllerServiceNode Failed to invoke @OnEnabled method of StandardMyService[id=43ef57e8-0174-1000-843d-d32a07ba02bb] due to java.lang.NoClassDefFoundError: virtuoso/jdbc4/VirtuosoConnectionPoolDataSource 2020-08-31 13:50:03,567 ERROR [Timer-Driven Process Thread-4] e.e.c.dct.Virtuoso.StandardMyService StandardMyService[id=43ef57e8-0174-1000-843d-d32a07ba02bb] Could not Shut Down Repository: java.lang.NullPointerException java.lang.NullPointerException: null at eu.everis.cordis.dct.Virtuoso.StandardMyService.shutdown(StandardMyService.java:187) at jdk.internal.reflect.GeneratedMethodAccessor376.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:142)

Hope someone can explain where the problem comes from,
BR,
Tino

Re: NoClassDefFoundError custom controller using external jars

Constan — Thu, 03 Sep 2020 13:35:51 GMT

An update since I managed to solve the issue. I followed the advice given in this StackOverflow post https://stackoverflow.com/questions/364114/can-i-add-jars-to-maven-2-build-classpath-without-installing-them by creating a static in-project repository so that maven can have better access to the jars. It seemed to do the trick.

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NoClassDefFoundError custom controller using external jars

Re: NoClassDefFoundError custom controller using external jars