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.id;
023
024import de.novanic.eventservice.service.exception.NoSessionAvailableException;
025
026import javax.servlet.http.HttpServletRequest;
027import javax.servlet.http.HttpSession;
028
029/**
030 * A {@link de.novanic.eventservice.service.connection.id.ConnectionIdGenerator} generates unique ids which are used to
031 * identify the connected clients / users.
032 *
033 * That implementation of {@link de.novanic.eventservice.service.connection.id.ConnectionIdGenerator} uses session ids
034 * as a unique connection / client id.
035 *
036 * @author sstrohschein
037 *         <br>Date: 28.03.2010
038 *         <br>Time: 23:34:26
039 */
040public class SessionConnectionIdGenerator implements ConnectionIdGenerator
041{
042    /**
043     * Generates a new connection / client id.
044     * The {@link de.novanic.eventservice.service.connection.id.SessionConnectionIdGenerator} creates a new session with that call when
045     * no session is available.
046     * @param aRequest request from the client
047     * @return unique connection / client id
048     */
049    public String generateConnectionId(HttpServletRequest aRequest) {
050        return aRequest.getSession(true).getId();
051    }
052
053    /**
054     * Returns the previous generated connection / client id
055     * (see {@link de.novanic.eventservice.service.connection.id.ConnectionIdGenerator#generateConnectionId(javax.servlet.http.HttpServletRequest)})
056     * without generating a new connection / client id.
057     * @see de.novanic.eventservice.service.connection.id.ConnectionIdGenerator#generateConnectionId(javax.servlet.http.HttpServletRequest)
058     * @param aRequest request
059     * @return the previous generated connection / client id for the specific client
060     */
061    public String getConnectionId(HttpServletRequest aRequest) {
062        final HttpSession theSession = aRequest.getSession(false);
063        if(theSession == null) {
064            throw new NoSessionAvailableException("There is no session available! Maybe no session was generated explicitly by the connection id generator.");
065        }
066        return theSession.getId();
067    }
068}