001    /*
002      GRANITE DATA SERVICES
003      Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.
004    
005      This file is part of Granite Data Services.
006    
007      Granite Data Services is free software; you can redistribute it and/or modify
008      it under the terms of the GNU Library General Public License as published by
009      the Free Software Foundation; either version 2 of the License, or (at your
010      option) any later version.
011    
012      Granite Data Services is distributed in the hope that it will be useful, but
013      WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
014      FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
015      for more details.
016    
017      You should have received a copy of the GNU Library General Public License
018      along with this library; if not, see <http://www.gnu.org/licenses/>.
019    */
020    
021    package org.granite.clustering;
022    
023    import java.io.IOException;
024    
025    import javax.servlet.Filter;
026    import javax.servlet.FilterChain;
027    import javax.servlet.FilterConfig;
028    import javax.servlet.ServletException;
029    import javax.servlet.ServletRequest;
030    import javax.servlet.ServletResponse;
031    import javax.servlet.http.HttpServletRequest;
032    
033    /**
034     * This filter forces the creation of an HTTP session. Only useful in cluster
035     * environments when sticky-session is enabled, in order to ensure that a client
036     * will always use the same cluster node.
037     * 
038     * @author Franck WOLFF
039     */
040    public class CreateSessionFilter implements Filter {
041    
042            public void init(FilterConfig config) throws ServletException {
043            }
044    
045            public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
046                    ((HttpServletRequest)request).getSession(true);
047                    chain.doFilter(request, response);
048            }
049    
050            public void destroy() {
051            }
052    }