Java tutorial
/** * Vosao CMS. Simple CMS for Google App Engine. * * Copyright (C) 2009-2010 Vosao development team. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * email: vosao.dev@gmail.com */ package org.vosao.business.impl.mq; import static com.google.appengine.api.taskqueue.TaskOptions.Builder.withUrl; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.codec.binary.Base64; import org.apache.commons.lang.StringUtils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.vosao.business.Business; import org.vosao.business.impl.mq.subscriber.EntityRemove; import org.vosao.business.impl.mq.subscriber.ExportTaskSubscriber; import org.vosao.business.impl.mq.subscriber.FileChangedSubscriber; import org.vosao.business.impl.mq.subscriber.ImportFile; import org.vosao.business.impl.mq.subscriber.ImportFolder; import org.vosao.business.impl.mq.subscriber.ImportTaskSubscriber; import org.vosao.business.impl.mq.subscriber.IndexChangedPages; import org.vosao.business.impl.mq.subscriber.IndexDeletedPages; import org.vosao.business.impl.mq.subscriber.PageCacheClear; import org.vosao.business.impl.mq.subscriber.PagePublishCron; import org.vosao.business.impl.mq.subscriber.Reindex; import org.vosao.business.mq.Message; import org.vosao.business.mq.MessageQueue; import org.vosao.business.mq.QueueSpeed; import org.vosao.business.mq.Topic; import org.vosao.business.mq.Subscriber; import org.vosao.common.VosaoContext; import org.vosao.global.SystemService; import org.vosao.servlet.MessageQueueServlet; import org.vosao.utils.StreamUtil; import com.google.appengine.api.taskqueue.Queue; /** * * @author Alexander Oleynik * */ public class MessageQueueImpl implements MessageQueue { private static final Log logger = LogFactory.getLog(MessageQueueImpl.class); private Map<String, List<Class>> subscribers = new HashMap<String, List<Class>>(); public MessageQueueImpl() { registerSubscribers(); } private void registerSubscribers() { subscribe(Topic.FILE_CHANGED, FileChangedSubscriber.class); subscribe(Topic.EXPORT, ExportTaskSubscriber.class); subscribe(Topic.IMPORT, ImportTaskSubscriber.class); subscribe(Topic.PAGES_DELETED, IndexDeletedPages.class); subscribe(Topic.PAGES_DELETED, PageCacheClear.class); subscribe(Topic.PAGES_CHANGED, IndexChangedPages.class); subscribe(Topic.PAGES_CHANGED, PageCacheClear.class); subscribe(Topic.PAGE_CACHE_CLEAR, PageCacheClear.class); subscribe(Topic.REINDEX, Reindex.class); subscribe(Topic.IMPORT_FILE, ImportFile.class); subscribe(Topic.IMPORT_FOLDER, ImportFolder.class); subscribe(Topic.ENTITY_REMOVE, EntityRemove.class); subscribe(Topic.PAGE_PUBLISH_CRON, PagePublishCron.class); } private SystemService getSystemService() { return VosaoContext.getInstance().getBusiness().getSystemService(); } private String getQueueName(Message message) { if (message.getSpeed() == null) { return "mq-high"; } else if (message.getSpeed().equals(QueueSpeed.HIGH)) { return "mq-high"; } else if (message.getSpeed().equals(QueueSpeed.MEDIUM)) { return "mq-medium"; } else if (message.getSpeed().equals(QueueSpeed.LOW)) { return "mq-low"; } return "mq-high"; } @Override public void publish(Message message) { Queue queue = getSystemService().getQueue(getQueueName(message)); if (message.getTopic() == null) { logger.error("Topic is null in message " + message); return; } queue.add(withUrl(MessageQueueServlet.MQ_URL).param("message", Base64.encodeBase64(StreamUtil.toBytes(message)))); } @Override public void subscribe(Topic topic, Class subscriber) { subscribe(topic.name(), subscriber); } @Override public void subscribe(String topic, Class subscriber) { if (!subscribers.containsKey(topic)) { subscribers.put(topic, new ArrayList<Class>()); } if (!subscribers.get(topic).contains(subscriber)) { subscribers.get(topic).add(subscriber); } } @Override public void unsubscribe(String topic, Class subscriber) { if (subscribers.containsKey(topic)) { if (subscribers.get(topic).contains(subscriber)) { subscribers.get(topic).remove(subscriber); } } } @Override public void execute(Message message) { if (subscribers.containsKey(message.getTopic())) { for (Class subscriberClass : subscribers.get(message.getTopic())) { try { Subscriber subscriber = (Subscriber) subscriberClass.newInstance(); subscriber.onMessage(message); } catch (IllegalAccessException e) { logger.error(e.getMessage()); } catch (InstantiationException e) { logger.error(e.getMessage()); } } } if (!StringUtils.isEmpty(message.getCommandClassName())) { try { Class clazz = loadClass(message.getCommandClassName()); if (clazz != null) { Subscriber subscriber = (Subscriber) clazz.newInstance(); subscriber.onMessage(message); } else { logger.error("Command class not found: " + message.getCommandClassName()); } } catch (IllegalAccessException e) { logger.error(e.getMessage()); } catch (InstantiationException e) { logger.error(e.getMessage()); } } } private Class loadClass(String name) { try { return this.getClass().getClassLoader().loadClass(name); } catch (ClassNotFoundException e) { } return getBusiness().getPluginBusiness().loadClass(name); } private Business getBusiness() { return VosaoContext.getInstance().getBusiness(); } }