001 /*
002 * Copyright (C) The Apache Software Foundation. All rights reserved.
003 *
004 * This software is published under the terms of the Apache Software License
005 * version 1.1, a copy of which has been included with this distribution in
006 * the LICENSE file.
007 *
008 * $Id: MessengerServlet.java 155459 2005-02-26 13:24:44Z dirkv $
009 */
010 package org.apache.commons.messenger;
011
012 import java.io.BufferedReader;
013 import java.io.IOException;
014 import java.io.PrintWriter;
015
016 import javax.jms.Destination;
017 import javax.jms.JMSException;
018 import javax.jms.Message;
019 import javax.jms.TextMessage;
020 import javax.servlet.ServletException;
021 import javax.servlet.http.HttpServlet;
022 import javax.servlet.http.HttpServletRequest;
023 import javax.servlet.http.HttpServletResponse;
024
025
026 /** <p><code>MessengerServlet</code> is a simple servlet that
027 * dispatches the current HTTP GET to a JMS connection to a receiveNoWait() call
028 * or a HTTP POST to send() message.</p>
029 *
030 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
031 * @version $Revision: 155459 $
032 */
033 public class MessengerServlet extends HttpServlet {
034
035 private static final String KEY_MESSENGER = "messenger";
036 private static final String KEY_DESTINATION= "destination";
037
038 /** Holds value of property messenger. */
039 private Messenger messenger;
040
041 /** Holds value of property destination. */
042 private Destination destination;
043
044 public MessengerServlet() {
045 }
046
047 public void init() throws ServletException {
048 try {
049 String name = getRequiredInitParmeter( KEY_MESSENGER, "Name of the Messenger to use for this servlet" );
050 String subject = getRequiredInitParmeter( KEY_DESTINATION, "Destination to be used for this servlet" );
051 Messenger messenger = MessengerManager.get( name );
052 if ( messenger == null ) {
053 throw new ServletException( "No Messenger configuration exists for name: " + name );
054 }
055 Destination destination = messenger.getDestination( subject );
056 if ( destination == null ) {
057 throw new ServletException( "No Destination exists for subject: " + subject );
058 }
059 setMessenger( messenger );
060 setDestination( destination );
061 }
062 catch (JMSException e) {
063 throw new ServletException( "Failed to initialise Messenger and Destination: " + e, e );
064 }
065 }
066
067
068 // Properties
069 //-------------------------------------------------------------------------
070
071 /** Getter for property messenger.
072 * @return Value of property messenger.
073 */
074 public Messenger getMessenger() {
075 return messenger;
076 }
077
078 /** Setter for property messenger.
079 * @param messenger New value of property messenger.
080 */
081 public void setMessenger(Messenger messenger) {
082 this.messenger = messenger;
083 }
084
085 /** Getter for property destination.
086 * @return Value of property destination.
087 */
088 public Destination getDestination() {
089 return destination;
090 }
091
092 /** Setter for property destination.
093 * @param destination New value of property destination.
094 */
095 public void setDestination(Destination destination) {
096 this.destination = destination;
097 }
098
099 // Implementation methods
100 //-------------------------------------------------------------------------
101 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
102 try {
103 Message message = getMessenger().receiveNoWait( getDestination() );
104 if ( message != null ) {
105 // output the message
106 writeMessage(message, request, response);
107 }
108 }
109 catch (IOException e) {
110 throw new ServletException(e);
111 }
112 catch (JMSException e) {
113 throw new ServletException(e);
114 }
115 }
116
117 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException {
118 try {
119 Message message = readMessage(request, response);
120 if ( message != null ) {
121 getMessenger().send( getDestination(), message );
122 }
123 }
124 catch (IOException e) {
125 throw new ServletException(e);
126 }
127 catch (JMSException e) {
128 throw new ServletException(e);
129 }
130 }
131
132 protected void doPut(HttpServletRequest request, HttpServletResponse response) throws ServletException {
133 try {
134 Message message = readMessage(request, response);
135 if ( message != null ) {
136 getMessenger().send( getDestination(), message );
137 }
138 }
139 catch (IOException e) {
140 throw new ServletException(e);
141 }
142 catch (JMSException e) {
143 throw new ServletException(e);
144 }
145 }
146
147 /**
148 * Derived classes may wish to change how a JMS Message is read from an incoming
149 * request, e.g. using an XML format, such as SOAP or XML-RPC.
150 */
151 protected Message readMessage(HttpServletRequest request, HttpServletResponse response) throws IOException, JMSException, ServletException {
152 // #### we could read the parameters as JMS properties...
153 StringBuffer buffer = new StringBuffer();
154 BufferedReader reader = request.getReader();
155 for ( String line; (line = reader.readLine()) != null; ) {
156 buffer.append(line);
157 }
158 String text = buffer.toString();
159 Message message = null;
160 if ( text.length() == 0 ) {
161 message = getMessenger().createMessage();
162 }
163 else {
164 message = getMessenger().createTextMessage(text);
165 }
166 return message;
167 }
168
169 protected void writeMessage(Message message, HttpServletRequest request, HttpServletResponse response) throws IOException, JMSException, ServletException {
170 // #### we could output the JMS properties as HTTP headers...
171 PrintWriter writer = response.getWriter();
172 if ( message instanceof TextMessage ) {
173 TextMessage textMessage = (TextMessage) message;
174 writer.write( textMessage.getText() );
175 }
176 }
177
178
179 protected String getRequiredInitParmeter(String key, String description) throws ServletException {
180 String value = getInitParameter( key );
181 if ( value == null || value.length() == 0 ) {
182 throw new ServletException(
183 "No initialization parameter for parameter: " + key
184 + " description: " + description
185 );
186 }
187 return value;
188 }
189 }
190