/* 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.application.impl;
import java.lang.ref.WeakReference;
import org.camunda.bpm.application.AbstractProcessApplication;
import org.camunda.bpm.application.ProcessApplicationReference;
import org.camunda.bpm.application.ProcessApplicationUnavailableException;
import org.camunda.bpm.engine.ProcessEngine;
/**
* <p>A {@link ProcessApplicationReference} implementation using
* {@link WeakReference}.</p>
*
* <p>As long as the process application is deployed, the container or the
* application will hold a strong reference to the {@link AbstractProcessApplication}
* object. This class holds a {@link WeakReference}. When the process
* application is undeployed, the container or application releases all strong
* references. Since we only pass {@link ProcessApplicationReference
* ProcessApplicationReferences} to the process engine, it is guaranteed that
* the {@link AbstractProcessApplication} object can be reclaimed by the garbage
* collector, even if the undeployment and unregistration should fail for some
* improbable reason.</p>
*
* @author Daniel Meyer
*
*/
public class ProcessApplicationReferenceImpl implements ProcessApplicationReference {
/** the weak reference to the process application */
protected WeakReference<AbstractProcessApplication> processApplication;
protected String name;
public ProcessApplicationReferenceImpl(AbstractProcessApplication processApplication) {
this.processApplication = new WeakReference<AbstractProcessApplication>(processApplication);
this.name = processApplication.getName();
}
public String getName() {
return name;
}
public AbstractProcessApplication getProcessApplication() throws ProcessApplicationUnavailableException {
AbstractProcessApplication application = processApplication.get();
if (application == null) {
throw new ProcessApplicationUnavailableException();
} else {
return application;
}
}
public void processEngineStopping(ProcessEngine processEngine) throws ProcessApplicationUnavailableException {
// do nothing
}
public void clear() {
processApplication.clear();
}
}