Starting a DMN Engine in a Bean does not work

Question

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().buildEngine();

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>

Answer 1

I use a workaround/hack to get the DMNEngine from the processEngine.

ProcessEngineConfiguration processEngineConfiguration = processEngine.getProcessEngineConfiguration();

Method method;
DmnEngine dmnEngine;
try {
    method = ProcessEngineConfigurationImpl.class.getMethod("getDmnEngine");
    dmnEngine = (DmnEngine) method.invoke(processEngineConfiguration);

} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException
        | SecurityException e) {
    e.printStackTrace();
}