Starting a DMN Engine in a Bean does not work

AvneeshKohli · December 13, 2019, 9:19am

I will build a DMN Engine in a Bean. DMN Engine with a BPMN Business Rule Task works fine, but not the standalone way. Camunda 7.6 runs into a JBoss-EAP 7(Same WildFly Distribution) and I think the modules are on the right places. But the following code throws an error message.

DmnEngine dmnEngine = DmnEngineConfiguration.createDefaultDmnEngineConfiguration().buildEng

DecisionService is not enough for me because I want to read the inputs from DecisionLogic .

Caused by: java.lang.NoClassDefFoundError: javax/el/ELContext
    at org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.initElProvider(DefaultDmnEngineConfiguration.java:128)
    at org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.init(DefaultDmnEngineConfiguration.java:78)
    at org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.buildEngine(DefaultDmnEngineConfiguration.java:69)
    at // DmnEngineConfiguration.createDefaultDmnEngineConfiguration().buildEngine();
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.jboss.as.ee.component.ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptor.java:52)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:437)
    at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.doMethodInterception(Jsr299BindingsInterceptor.java:82)
    at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.processInvocation(Jsr299BindingsInterceptor.java:93)
    at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.as.ejb3.component.invocationmetrics.ExecutionTimeInterceptor.processInvocation(ExecutionTimeInterceptor.java:43)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.as.jpa.interceptor.SBInvocationInterceptor.processInvocation(SBInvocationInterceptor.java:47)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:437)
    at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:64)
    at org.jboss.as.weld.ejb.EjbRequestScopeActivationInterceptor.processInvocation(EjbRequestScopeActivationInterceptor.java:83)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.as.ee.concurrent.ConcurrentContextInterceptor.processInvocation(ConcurrentContextInterceptor.java:45)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
    at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:52)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.as.ejb3.component.pool.PooledInstanceInterceptor.processInvocation(PooledInstanceInterceptor.java:51)
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
    at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInCallerTx(CMTTxInterceptor.java:254)
    ... 324 more
Caused by: java.lang.ClassNotFoundException: javax.el.ELContext from [Module "org.camunda.bpm.dmn.camunda-engine-dmn:main" from local module loader @66133adc (finder: local module finder @7bfcd12c (roots: [JBOSS_HOME]\modules, [JBOSS_HOME]\modules\system\layers\base))]
    at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:198)
    at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:363)
    at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:351)
    at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:93)
    ... 357 more

The modul org.camunda.bpm.dmn.camunda-engine-dmn:main is there

Maven Dependencies

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.camunda.bpm</groupId>
            <artifactId>camunda-bom</artifactId>
            <version>${camunda.version}</version>
            <scope>import</scope>
            <type>pom</type>
        </dependency>
        <dependency>
            <groupId>org.camunda.bpm.dmn</groupId>
            <artifactId>camunda-engine-dmn-bom</artifactId>
            <version>${camunda.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        ...
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>org.camunda.bpm</groupId>
        <artifactId>camunda-engine</artifactId>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.camunda.bpm.dmn</groupId>
        <artifactId>camunda-engine-dmn</artifactId>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.camunda.bpm.javaee</groupId>
        <artifactId>camunda-ejb-client</artifactId>
    </dependency>
    <dependency>
        <groupId>org.camunda.bpm</groupId>
        <artifactId>camunda-engine-cdi</artifactId>
    </dependency>
    ...
<dependencies>

langfr · December 13, 2019, 10:03am

The module org.camunda.bpm.dmn.camunda-engine-dmn:main cannot find the class javax.el.ELContext,
You can fix this editing the file
$JBOSS_HOME\modules\org\camunda\bpm\dmn\camunda-engine-dmn\main\module.xml
and adding
<module name="javax.el.api"/>
as another dependency.
Restart JBoss EAP / Wildfly afterwards.

Stephan7 · January 31, 2023, 10:59am

Hello all,
I know this issue is already old, but i keep running into the exact same problem with the provided current Wildfly-26.0.1-Camunda-7-18.0 stack.

I have added the module “javax.el.api” as described in the Post above, but after the restart I get the following error:

java.lang.NoClassDefFoundError: de/odysseus/el/util/SimpleContext at [org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.initElProvider](mailto:org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.initElProvider)(DefaultDmnEngineConfiguration.java:178) at [org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.init](mailto:org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.init)(DefaultDmnEngineConfiguration.java:96) at [org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.buildEngine](mailto:org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.buildEngine)(DefaultDmnEngineConfiguration.java:86)

I found out, that the mentioned class “de/odysseus/el/util/SimpleContext” is contained in the juel-impl-2.2.7.jar, but when I add this one also as a Jboss-module (via jboss_cli) and add the module also to the module.xml of the camunda-engine-dmn, then I get even stranger errors which I can provide if needed.

For me it seems unclear, if the programmatic initialization of the DmnEngineConfiguration is conceptually really meant to work also inside a Jboss or only inside standalone applications. I would have preferred to get my following initialization code running also inside Jboss, but I suspect, that I am meant to deploy the DMN-Files and run the decision evaluation via REST-API.

        dmnEngineConfiguration = DmnEngineConfiguration.createDefaultDmnEngineConfiguration();
        dmnEngine = dmnEngineConfiguration.buildEngine();
        InputStream inputStream = resourceFileReader.getFileFromResourceAsInputStream(DMN_FILE_NAME);
        DmnModelInstance dmnModelInstance = Dmn.readModelFromStream(inputStream);
        dmnDecision = dmnEngine.parseDecision(DMN_DECISION_KEY, dmnModelInstance);

Is there anyone who can clarify this?

Many thanks in advance,
Stephan

langfr · February 1, 2023, 4:48pm

I cannot reproduce your problem.

Class de.odysseus.el.util.SimpleContext
is in org/camunda/bpm/dmn/camunda-engine-feel-juel/main/camunda-engine-feel-juel-<Camunda Version>.jar
as **camundafeel/**de/odysseus/el/util/SimpleContext.class
and module org.camunda.bpm.dmn.camunda-engine-dmn has a dependency on org.camunda.bpm.dmn.camunda-engine-feel-juel.

Your error with line breaks is

java.lang.NoClassDefFoundError: de/odysseus/el/util/SimpleContext
 at [org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.initElProvider](mailto:org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.initElProvider)(DefaultDmnEngineConfiguration.java:178) 
 at [org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.init](mailto:org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.init)(DefaultDmnEngineConfiguration.java:96) 
 at [org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.buildEngine](mailto:org.camunda.bpm.dmn.camunda-engine-dmn@7.18.0//org.camunda.bpm.dmn.engine.impl.DefaultDmnEngineConfiguration.buildEngine)(DefaultDmnEngineConfiguration.java:86)

I tried this without any problems:

  DmnEngineConfiguration dmnEngineConfiguration = DmnEngineConfiguration.createDefaultDmnEngineConfiguration();
  DmnEngine dmnEngine = dmnEngineConfiguration.buildEngine();
  DmnModelInstance dmnModelInstance = Dmn.readModelFromFile( new File( "/mbi/mbi2e_all/bpm/sus_Retoure_CandidateUser.dmn" ) );
  List<DmnDecision> decisions = dmnEngine.parseDecisions( dmnModelInstance );
  for ( DmnDecision decision : decisions ) {
    CamundaInterface.LOGGER.debug( decision );
   }

Which Java Version you’re using ? I’m still on Java 8. Can you try with Java 8 ?
Also using Wildfly 26.0.1 but with Camunda 7.19.0-SNAPSHOT, but this should not make a difference.

Stephan7 · February 2, 2023, 9:19am

Thank you for your efforts!
I saw already that SimpleContext also exists in camunda-engine-feel-juel, but as you mentioned, it is in a different package. So that one didn’t seem to be a way out, because the ClassNotFound goes explicitly for “de.odysseus.el.util.SimpleContext”. That’s why I finally suspected that this kind of init code is not meant to run inside jboss because something is screwn up there with the dependencies.

I could try with Java 8, but that would just be for theory because my task includes a migration from Java 8 to Java 11 and so this code will definitely have to run with java 11 anyway.

Thanks again,
Stephan

langfr · February 2, 2023, 6:16pm

Stephan,
perhaps this old thread is helpful for you to solve your problem:
https://groups.google.com/g/camunda-bpm-users/c/Z2bKes3nIA0

Stephan7 · February 7, 2023, 10:40am

Hi Frank,
i tried the solution from your link and added these 3 dependencies so that they are included in WEB-INF/lib of my webapp, but the same error persists.
I also tried the approach to add the 3 deps either to jboss-deployment-structure.xml or to the “Dependencies:” key of the MANIFEST.MF but always the same error.
I also verified that my changes got deployed to wildfly correctly by looking into the war file under standalone/deployments to make sure that the desired change has really been incorporated into the artifact.
Any other ideas? Otherwise I will give up on this and we will go with the Shared Engine approach - which works but which is of course slower because every evaluation of a decisiontable gets written to the database. My client does a) not see the need for this persistence mechanism and b) prefers the better performance without persistence. Is there at least a way to disable the persistence of the evaluation?

Many thanks again,
Stephan

system · January 30, 2024, 12:06pm