org.apache.felix.eventadmin/src/main/java/org/apache/felix/eventadmin/impl/adapter/ServiceEventAdapter.java

/*
 *   Copyright 2005 The Apache Software Foundation
 *
 *   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.apache.felix.eventadmin.impl.adapter;

import java.util.Dictionary;
import java.util.Hashtable;

import org.apache.felix.eventadmin.impl.util.LogWrapper;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventAdmin;
import org.osgi.service.event.EventConstants;

/**
 * This class registers itself as a listener for service events and posts them via
 * the EventAdmin as specified in 113.6.5 OSGi R4 compendium.
 * 
 * @author <a href="mailto:felix-dev@incubator.apache.org">Felix Project Team</a>
 */
public class ServiceEventAdapter implements ServiceListener
{
    private final EventAdmin m_admin;
    
    /**
     * The constructor of the adapter. This will register the adapter with the
     * given context as a <tt>ServiceListener</tt> and subsequently, will
     * post received events via the given EventAdmin.
     * 
     * @param context The bundle context with which to register as a listener.
     * @param admin The <tt>EventAdmin</tt> to use for posting events.
     */
    public ServiceEventAdapter(final BundleContext context, final EventAdmin admin)
    {
        m_admin = admin;
        
        context.addServiceListener(this);
    }

    /**
     * Once a Service event is received this method assembles and posts an event 
     * via the <tt>EventAdmin</tt> as specified in 113.6.5 OSGi R4 compendium. 
     * 
     * @param event The event to adapt.
     */
    public void serviceChanged(final ServiceEvent event)
    {
        final Dictionary properties = new Hashtable();

        properties.put(EventConstants.EVENT, event);

        properties.put(EventConstants.SERVICE, event
            .getServiceReference());

        final Object id = event.getServiceReference().getProperty(
            EventConstants.SERVICE_ID);

        if (null != id)
        {
            try
            {
                properties.put(EventConstants.SERVICE_ID, new Long(id
                    .toString()));
            } catch (NumberFormatException ne)
            {
                // LOG and IGNORE
                LogWrapper.getLogger().log(event.getServiceReference(),
                    LogWrapper.LOG_WARNING, "Exception parsing " + 
                    EventConstants.SERVICE_ID + "=" + id, ne);
            }
        }

        final Object pid = event.getServiceReference().getProperty(
            EventConstants.SERVICE_PID);

        if (null != pid)
        {
            properties.put(EventConstants.SERVICE_PID, pid.toString());
        }

        final Object objectClass = event.getServiceReference()
            .getProperty(Constants.OBJECTCLASS);

        if (null != objectClass)
        {
            if (objectClass instanceof String[])
            {
                properties.put(EventConstants.SERVICE_OBJECTCLASS,
                    objectClass);
            }
            else
            {
                properties.put(EventConstants.SERVICE_OBJECTCLASS,
                    new String[] { objectClass.toString() });
            }
        }

        final StringBuffer topic = new StringBuffer(ServiceEvent.class
            .getName().replace('.', '/')).append('/');

        switch (event.getType())
        {
            case ServiceEvent.REGISTERED:
                topic.append("REGISTERED");
                break;
            case ServiceEvent.MODIFIED:
                topic.append("MODIFIED");
                break;
            case ServiceEvent.UNREGISTERING:
                topic.append("UNREGISTERING");
                break;
            default:
                return; // IGNORE
        }

        try {
            m_admin.postEvent(new Event(topic.toString(), properties));
        } catch(IllegalStateException e) {
            // This is o.k. - indicates that we are stopped.
        }
    }
}