001/*
002 * GWTEventService
003 * Copyright (c) 2011 and beyond, strawbill UG (haftungsbeschr?nkt)
004 *
005 * This is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU Lesser General Public License as
007 * published by the Free Software Foundation; either version 3 of
008 * the License, or (at your option) any later version.
009 * Other licensing for GWTEventService may also be possible on request.
010 * Please view the license.txt of the project for more information.
011 *
012 * This software is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * You should have received a copy of the GNU Lesser General Public
018 * License along with this software; if not, write to the Free
019 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021 */
022package de.novanic.eventservice.service.connection.strategy.connector.longpolling;
023
024import de.novanic.eventservice.client.event.DomainEvent;
025import de.novanic.eventservice.config.EventServiceConfiguration;
026import de.novanic.eventservice.service.EventServiceException;
027import de.novanic.eventservice.service.connection.strategy.connector.ConnectionStrategyServerConnectorAdapter;
028import de.novanic.eventservice.service.registry.user.UserInfo;
029
030import java.util.List;
031
032/**
033 * The {@link de.novanic.eventservice.service.connection.strategy.connector.longpolling.LongPollingServerConnector} implements
034 * the long-polling event listen method. Long-polling means that the connection is hold open for a specified time and when an event
035 * occurs, the answer / event is sent directly to the client.
036 *
037 * The {@link de.novanic.eventservice.service.connection.strategy.connector.ConnectionStrategyServerConnector} listens for occurring events ({@link de.novanic.eventservice.client.event.Event})
038 * on the server side and has the task to prepare the transfer from the server side to the client side.
039 * @author sstrohschein
040 *         <br>Date: 15.03.2010
041 *         <br>Time: 23:00:24
042 */
043public class LongPollingServerConnector extends ConnectionStrategyServerConnectorAdapter
044{
045    /**
046     * Creates a new {@link de.novanic.eventservice.service.connection.strategy.connector.longpolling.LongPollingServerConnector}.
047     * The {@link de.novanic.eventservice.service.connection.strategy.connector.longpolling.LongPollingServerConnector} implements
048     * the long-polling event listen method.
049     * @param aConfiguration configuration
050     */
051    public LongPollingServerConnector(EventServiceConfiguration aConfiguration) {
052        super(aConfiguration);
053    }
054
055    /**
056     * Listens for occurring events with the long-polling strategy. The connection is hold open for a specified time and when an event occurs,
057     * the answer / event is sent directly to the client.
058     * @param aUserInfo {@link de.novanic.eventservice.service.registry.user.UserInfo} which holds new occurred events
059     * @return occurred events
060     * @throws EventServiceException
061     */
062    public List<DomainEvent> listen(UserInfo aUserInfo) throws EventServiceException {
063        waitMinWaitingTime();
064        waitMaxWaitingTime(aUserInfo);
065        return aUserInfo.retrieveEvents(getConfiguration().getMaxEvents());
066    }
067}