org.camunda.bpm.engine.impl.el.ProcessApplicationElResolverDelegate Maven / Gradle / Ivy
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* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
* under one or more contributor license agreements. See the NOTICE file
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* ownership. Camunda licenses this file to you under the Apache License,
* Version 2.0; you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
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package org.camunda.bpm.engine.impl.el;
import org.camunda.bpm.application.ProcessApplicationInterface;
import org.camunda.bpm.application.ProcessApplicationReference;
import org.camunda.bpm.application.ProcessApplicationUnavailableException;
import org.camunda.bpm.engine.ProcessEngineException;
import org.camunda.bpm.engine.impl.context.Context;
import org.camunda.bpm.impl.juel.jakarta.el.CompositeELResolver;
import org.camunda.bpm.impl.juel.jakarta.el.ELResolver;
/**
* This is an {@link ELResolver} implementation that delegates to a ProcessApplication-provided
* {@link ELResolver}. The idea is that in a multi-application setup, a shared process engine may orchestrate
* multiple process applications. In this setting we want to delegate to the current process application
* for performing expression resolving. This also allows individual process applications to integrate with
* different kinds of Di Containers or other expression-context providing frameworks. For instance, a first
* process application may use the spring application context for resolving Java Delegate implementations
* while a second application may use CDI or even an Apache Camel Context.
*
* The behavior of this implementation is as follows: if we are not currently running in the context of
* a process application, we are skipped. If we are, this implementation delegates to the underlying
* application-provided {@link ELResolver} which may itself be a {@link CompositeELResolver}.
*
* @author Daniel Meyer
*
*/
public class ProcessApplicationElResolverDelegate extends AbstractElResolverDelegate {
protected ELResolver getElResolverDelegate() {
ProcessApplicationReference processApplicationReference = Context.getCurrentProcessApplication();
if(processApplicationReference != null) {
try {
ProcessApplicationInterface processApplication = processApplicationReference.getProcessApplication();
return processApplication.getElResolver();
} catch (ProcessApplicationUnavailableException e) {
throw new ProcessEngineException("Cannot access process application '"+processApplicationReference.getName()+"'", e);
}
} else {
return null;
}
}
}