001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.engine;
016    
017    import java.io.IOException;
018    import java.util.HashMap;
019    import java.util.Map;
020    
021    import javax.servlet.http.HttpServletRequest;
022    import javax.servlet.http.HttpServletResponse;
023    import javax.servlet.http.HttpSession;
024    
025    import org.apache.commons.logging.Log;
026    import org.apache.tapestry.IRequestCycle;
027    import org.apache.tapestry.Tapestry;
028    import org.apache.tapestry.services.LinkFactory;
029    
030    /**
031     * Restarts the Tapestry application. This is normally reserved for dealing with
032     * catastrophic failures of the application. Discards the
033     * {@link javax.servlet.http.HttpSession}, if any, and redirects to the
034     * Tapestry application servlet URL (invoking the {@link HomeService}).
035     * 
036     * @author Howard Lewis Ship
037     * @since 1.0.9
038     */
039    
040    public class RestartService implements IEngineService
041    {
042    
043        /** @since 4.0 */
044        private Log _log;
045    
046        /** @since 4.0 */
047        private HttpServletRequest _request;
048    
049        /** @since 4.0 */
050        private HttpServletResponse _response;
051    
052        /** @since 4.0 */
053        private LinkFactory _linkFactory;
054    
055        /** @since 4.0 */
056        private String _servletPath;
057    
058        public ILink getLink(boolean post, Object parameter)
059        {
060            if (parameter != null)
061                throw new IllegalArgumentException(EngineMessages
062                        .serviceNoParameter(this));
063    
064            Map parameters = new HashMap();
065    
066            return _linkFactory.constructLink(this, post, parameters, true);
067        }
068    
069        public void service(IRequestCycle cycle)
070            throws IOException
071        {
072            HttpSession session = _request.getSession(false);
073    
074            if (session != null)
075            {
076                try
077                {
078                    session.invalidate();
079                }
080                catch (IllegalStateException ex)
081                {
082                    _log.warn("Exception thrown invalidating HttpSession.", ex);
083    
084                    // Otherwise, ignore it.
085                }
086            }
087    
088            String url = cycle.getAbsoluteURL(_servletPath);
089    
090            _response.sendRedirect(url);
091        }
092    
093        public String getName()
094        {
095            return Tapestry.RESTART_SERVICE;
096        }
097    
098        /** @since 4.0 */
099        public void setLog(Log log)
100        {
101            _log = log;
102        }
103    
104        /** @since 4.0 */
105        public void setRequest(HttpServletRequest request)
106        {
107            _request = request;
108        }
109    
110        /** @since 4.0 */
111        public void setResponse(HttpServletResponse response)
112        {
113            _response = response;
114        }
115    
116        /** @since 4.0 */
117        public void setLinkFactory(LinkFactory linkFactory)
118        {
119            _linkFactory = linkFactory;
120        }
121    
122        /** @since 4.0 */
123        public void setServletPath(String servletPath)
124        {
125            _servletPath = servletPath;
126        }
127    }