OsgiServiceRegistry.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.camel.core.osgi;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;

import org.apache.camel.CamelContext;
import org.apache.camel.spi.Registry;
import org.apache.camel.support.LifecycleStrategySupport;
import org.apache.camel.util.ObjectHelper;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The OsgiServiceRegistry support to get the service object from the bundle context
 */
public class OsgiServiceRegistry extends LifecycleStrategySupport implements Registry {
    private static final Logger LOG = LoggerFactory.getLogger(OsgiCamelContextHelper.class);
    private final BundleContext bundleContext;
    private final Queue<ServiceReference<?>> serviceReferenceQueue = new ConcurrentLinkedQueue<ServiceReference<?>>();
    
    public OsgiServiceRegistry(BundleContext bc) {
        bundleContext = bc;
    }

    /**
     * Support to lookup the Object with filter with the (name=NAME) and class type
     */
    public <T> T lookupByNameAndType(String name, Class<T> type) {
        Object service = null;
        ServiceReference<?> sr  = null;
        try {
            ServiceReference<?>[] refs = bundleContext.getServiceReferences(type.getName(), "(name=" + name + ")");            
            if (refs != null && refs.length > 0) {
                // just return the first one
                sr = refs[0];
                serviceReferenceQueue.add(sr);
                service = bundleContext.getService(sr);
            }
        } catch (Exception ex) {
            throw ObjectHelper.wrapRuntimeCamelException(ex);
        }
        return type.cast(service);
    }

    /**
     * It's only support to look up the ServiceReference with Class name or service PID
     */
    public Object lookupByName(String name) {
        Object service = null;
        ServiceReference<?> sr = bundleContext.getServiceReference(name);
        if (sr == null) {
            // trying to lookup service by PID if not found by name
            String filterExpression = "(" + Constants.SERVICE_PID + "=" + name + ")";
            try {
                ServiceReference<?>[] refs = bundleContext.getServiceReferences((String)null, filterExpression);
                if (refs != null && refs.length > 0) {
                    // just return the first one
                    sr = refs[0];
                }
            } catch (InvalidSyntaxException ex) {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Invalid OSGi service reference filter, skipped lookup by service.pid. Filter expression: " + filterExpression, ex);
                }
            }
        }
        if (sr != null) {
            // Need to keep the track of Service
            // and call ungetService when the camel context is closed 
            serviceReferenceQueue.add(sr);
            service = bundleContext.getService(sr);
        }
        return service;
    }

    public <T> Map<String, T> findByTypeWithName(Class<T> type) {
        Map<String, T> result = new HashMap<String, T>();
        int count = 0;
        try {
            ServiceReference<?>[] refs = bundleContext.getAllServiceReferences(type.getName(), null);
            if (refs != null) {
                for (ServiceReference<?> sr : refs) {
                    if (sr != null) {
                        Object service = bundleContext.getService(sr);
                        serviceReferenceQueue.add(sr);
                        if (service != null) {
                            String name = (String)sr.getProperty("name");
                            if (name != null) {
                                result.put(name, type.cast(service));
                            } else {
                                // generate a unique name for it
                                result.put(type.getSimpleName() + count, type.cast(service));
                                count++;
                            }
                        }
                    }
                }
            }
        } catch (Exception ex) {
            throw ObjectHelper.wrapRuntimeCamelException(ex);
        }
        return result;
    }

    public <T> Set<T> findByType(Class<T> type) {
        Map<String, T> map = findByTypeWithName(type);
        return new HashSet<T>(map.values());
    }

    public Object lookup(String name) {
        return lookupByName(name);
    }

    public <T> T lookup(String name, Class<T> type) {
        return lookupByNameAndType(name, type);
    }

    public <T> Map<String, T> lookupByType(Class<T> type) {
        return findByTypeWithName(type);
    }

    @Override
    public void onContextStop(CamelContext context) {
        // Unget the OSGi service
        ServiceReference<?> sr = serviceReferenceQueue.poll();
        while (sr != null) {
            bundleContext.ungetService(sr);
            sr = serviceReferenceQueue.poll();
        }
        // Clean up the OSGi Service Cache
        serviceReferenceQueue.clear();
    }

}