/* Licensed under the Apache License, Version 2.0 (the "License");
* 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,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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.engine.impl.javax.el.CompositeELResolver;
import org.camunda.bpm.engine.impl.javax.el.ELResolver;
/**
* <p>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.</p>
*
* <p>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}.</p>
*
* @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;
}
}
}