/*

  * Copyright (C) The Apache Software Foundation. All rights reserved.

  *

  * This software is published under the terms of the Apache Software License

  * version 1.1, a copy of which has been included with this distribution in

  * the LICENSE file.

  *

  * $Id: MessengerServlet.java 155459 2005-02-26 13:24:44Z dirkv $

  */

 package org.apache.commons.messenger;

 import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.PrintWriter;

 import javax.jms.Destination;

 import javax.jms.JMSException;

 import javax.jms.Message;

 import javax.jms.TextMessage;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 /** <p><code>MessengerServlet</code> is a simple servlet that

  * dispatches the current HTTP GET to a JMS connection to a receiveNoWait() call

  * or a HTTP POST to send() message.</p>

  *

  * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>

  * @version $Revision: 155459 $

  */

 public class MessengerServlet extends HttpServlet {

     private static final String KEY_MESSENGER = "messenger";

     private static final String KEY_DESTINATION= "destination";

     /** Holds value of property messenger. */

     private Messenger messenger;

     /** Holds value of property destination. */

     private Destination destination;

     public MessengerServlet() {

     }

     public void init() throws ServletException {

         try {

             String name = getRequiredInitParmeter( KEY_MESSENGER, "Name of the Messenger to use for this servlet" );

             String subject = getRequiredInitParmeter( KEY_DESTINATION, "Destination to be used for this servlet" );

             Messenger messenger = MessengerManager.get( name );

             if ( messenger == null ) {

                 throw new ServletException( "No Messenger configuration exists for name: " + name );

             }

             Destination destination = messenger.getDestination( subject );

             if ( destination == null ) {

                 throw new ServletException( "No Destination exists for subject: " + subject );

             }

             setMessenger( messenger );

             setDestination( destination );

         }

         catch (JMSException e) {

             throw new ServletException( "Failed to initialise Messenger and Destination: " + e, e );

         }

     }

     // Properties

     //-------------------------------------------------------------------------    

     /** Getter for property messenger.

      * @return Value of property messenger.

      */

     public Messenger getMessenger() {

         return messenger;

     }

     /** Setter for property messenger.

      * @param messenger New value of property messenger.

      */

     public void setMessenger(Messenger messenger) {

         this.messenger = messenger;

     }

     /** Getter for property destination.

      * @return Value of property destination.

      */

     public Destination getDestination() {

         return destination;

     }

     /** Setter for property destination.

      * @param destination New value of property destination.

      */

     public void setDestination(Destination destination) {

         this.destination = destination;

     }

     // Implementation methods

     //-------------------------------------------------------------------------        

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {

         try {

             Message message = getMessenger().receiveNoWait( getDestination() );

             if ( message != null ) {

                 // output the message

                 writeMessage(message, request, response);

             }

         }

         catch (IOException e) {

             throw new ServletException(e);

         }

         catch (JMSException e) {

             throw new ServletException(e);

         }

     }

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException {

         try {

             Message message = readMessage(request, response);

             if ( message != null ) {

                 getMessenger().send( getDestination(), message );

             }

         }

         catch (IOException e) {

             throw new ServletException(e);

         }

         catch (JMSException e) {

             throw new ServletException(e);

         }

     }

     protected void doPut(HttpServletRequest request, HttpServletResponse response) throws ServletException {

         try {

             Message message = readMessage(request, response);

             if ( message != null ) {

                 getMessenger().send( getDestination(), message );

             }

         }

         catch (IOException e) {

             throw new ServletException(e);

         }

         catch (JMSException e) {

             throw new ServletException(e);

         }

     }

     /** 

      * Derived classes may wish to change how a JMS Message is read from an incoming

      * request, e.g. using an XML format, such as SOAP or XML-RPC.

      */

     protected Message readMessage(HttpServletRequest request, HttpServletResponse response) throws IOException, JMSException, ServletException {

         // #### we could read the parameters as JMS properties...

         StringBuffer buffer = new StringBuffer();

         BufferedReader reader = request.getReader();

         for ( String line; (line = reader.readLine()) != null; ) {

             buffer.append(line);

         }

         String text = buffer.toString();

         Message message = null;

         if ( text.length() == 0 ) {

             message = getMessenger().createMessage();

         }

         else {

             message = getMessenger().createTextMessage(text);

         }

         return message;

     }

     protected void writeMessage(Message message, HttpServletRequest request, HttpServletResponse response) throws IOException, JMSException, ServletException {

         // #### we could output the JMS properties as HTTP headers...

         PrintWriter writer = response.getWriter();

         if ( message instanceof TextMessage ) {

             TextMessage textMessage = (TextMessage) message;

             writer.write( textMessage.getText() );

         }

     }

     protected String getRequiredInitParmeter(String key, String description) throws ServletException {

         String value = getInitParameter( key );

         if ( value == null || value.length() == 0 ) {

             throw new ServletException( 

                 "No initialization parameter for parameter: " + key 

                 + " description: " + description 

             );

         }

         return value;

     }

 }