OSGiPlatformAbstraction.java

/****************************************************************************
 * Copyright (c) 2005, 2010 Jan S. Rellermeyer, Systems Group,
 * Department of Computer Science, ETH Zurich and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Jan S. Rellermeyer - initial API and implementation
 *    Markus Alexander Kuppe - enhancements and bug fixes
 *
*****************************************************************************/
package ch.ethz.iks.slp.impl;

import java.util.Dictionary;

import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceReference;
import org.osgi.service.log.LogService;

import ch.ethz.iks.slp.impl.filter.Filter;

/**
 * Platform abstraction for the OSGi implementation.
 * 
 * @author Jan S. Rellermeyer, ETH Zurich
 */
public class OSGiPlatformAbstraction implements PlatformAbstraction,
		ServiceListener {

	/**
	 * 
	 */
	private final BundleContext context;

	/**
	 * 
	 */
	private LogService log = new NullPatternLogService();		

	/**
	 * Constructor.
	 * 
	 * @param context
	 *            the bundle context from the OSGi framework.
	 * @param log
	 *            the LogService, or null.
	 * @param debug
	 *            true if debugging is enabled.
	 * @throws InvalidSyntaxException 
	 * 				may never happen
	 */
	OSGiPlatformAbstraction(BundleContext context) throws InvalidSyntaxException {
		this.context = context;

		// initially get the LogService
		final ServiceReference sref = context
				.getServiceReference(LogService.class.getName());
		if (sref != null) {
			this.log = (LogService) context.getService(sref);
		}

		// track the LogService for life cycle events
		context.addServiceListener(this, "(" + Constants.OBJECTCLASS + "=" + LogService.class.getName() + ")");

		logDebug("jSLP OSGi started.");
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#createFilter(java.lang.String)
	 */
	public Filter createFilter(String filterString) {
		try {
			final org.osgi.framework.Filter filter = context
					.createFilter(filterString);
			return new Filter() {
				public boolean match(Dictionary values) {
					return filter.match(values);
				}

				public String toString() {
					return filter.toString();
				}
			};
		} catch (InvalidSyntaxException e) {
			throw new IllegalArgumentException(e.getMessage());
		}
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logDebug(java.lang.String)
	 */
	public void logDebug(String message) {
		if(SLPCore.CONFIG.getDebugEnabled()) {
			log.log(LogService.LOG_DEBUG, message);
		}
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logDebug(java.lang.String,
	 *      java.lang.Throwable)
	 */
	public void logDebug(String message, Throwable exception) {
		if(SLPCore.CONFIG.getDebugEnabled()) {
			log.log(LogService.LOG_DEBUG, message, exception);
		}
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logError(java.lang.String)
	 */
	public void logError(String message) {
		log.log(LogService.LOG_ERROR, message);
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logError(java.lang.String,
	 *      java.lang.Throwable)
	 */
	public void logError(String message, Throwable exception) {
		log.log(LogService.LOG_ERROR, message, exception);
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logTraceMessage(java.lang.String)
	 */
	public void logTraceMessage(String message) {
		if(SLPCore.CONFIG.getTraceMessage()) {
			log.log(LogService.LOG_INFO, message);
		}
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logTraceDrop(java.lang.String)
	 */
	public void logTraceDrop(String message) {
		if(SLPCore.CONFIG.getTraceDrop()) {
			log.log(LogService.LOG_INFO, message);
		}
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logTraceMessage(java.lang.String)
	 */
	public void logTraceReg(String message) {
		if(SLPCore.CONFIG.getTraceReg()) {
			log.log(LogService.LOG_INFO, message);
		}
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logWarning(java.lang.String)
	 */
	public void logWarning(String message) {
		log.log(LogService.LOG_WARNING, message);
	}

	/**
	 * 
	 * @see ch.ethz.iks.slp.impl.PlatformAbstraction#logWarning(java.lang.String,
	 *      java.lang.Throwable)
	 */
	public void logWarning(String message, Throwable exception) {
		log.log(LogService.LOG_WARNING, message, exception);
	}

	/**
	 * 
	 * @see org.osgi.framework.ServiceListener#serviceChanged(org.osgi.framework.ServiceEvent)
	 */
	public void serviceChanged(final ServiceEvent event) {
		switch (event.getType()) {
		case ServiceEvent.REGISTERED:
			log = (LogService) context.getService(event.getServiceReference());
			return;
		case ServiceEvent.UNREGISTERING:
			log = new NullPatternLogService();
		default:
		}
	}
	
	// if no LogService is present, we use a dummy log
	private class NullPatternLogService implements LogService {

		public void log(int level, String message) {
			if(level == LogService.LOG_ERROR || level == LogService.LOG_WARNING) {
				System.err.println(message);
			} else {
				System.out.println(message);
			}
		}

		public void log(int level, String message, Throwable exception) {
			log(level, message + " " + exception.toString());
		}

		public void log(ServiceReference sr, int level, String message) {
			log(null, level, message);
		}

		public void log(ServiceReference sr, int level, String message, Throwable t) {
			log(null, level, message, t);
		}
	}
}