B2B with XML

Third-Party Hotel System Uses Email, AQ, and XML

Contents

• About AQ Messages and Queues
• Processing AQ Messages
• Handling Messages with a Servlet

The TPHS coordinates with the HRS application to update information and keep track of bookings for international hotels (also called third-party hotels). There are 2 modules in the TPHS:

• TPHotelSystem, implemented as a Java application, listens to the HRS via Advanced Queueing (AQ). When it receives an XML document containing booking information, this application parses it and updates the local schema.
• TPHSServlet provides an interface for the administrator at the TPHS site. Using this interface, the TPHS admin can add new room types to existing hotels, add new facilities, change room rates, etc. After making the changes, the administrator can notify the HRS via email. When the administrator presses the "Send Mail" button, this servlet fetches the new information from the database and mails it to the HRS in an XML document.

  public void startListening() {


    System.out.println("TPHotelSystem Started Listening on the queue...");
    String l_status = "START";
    try {
           ...
      while(!l_status.equals("FINISH")) {

       // Class xmla2a.utilities.AQHandler imports oracle.AQ.*.
       // AQHandler m_handler = null;
      	String l_xmlString = m_handler.dequeueMessage(m_handler.m_reqQueue);
      	ByteArrayInputStream l_bstream =
                             new ByteArrayInputStream(l_xmlString.getBytes());

        // Create an XML document from the given string.
        DOMParser l_parse = new DOMParser();

        l_parse.setPreserveWhitespace(false);
        l_parse.setValidationMode(true);
        l_parse.parse(l_bstream);

        XMLDocument l_doc = l_parse.getDocument();
        NodeList l_bookings=l_doc.getElementsByTagName("Booking");

        // Process all bookings in the XML document.
        for( int i=0; i< l_bookings.getLength(); i++){
          NodeList l_booking = l_bookings.item(i).getChildNodes();
          NodeList l_bookingType = l_booking.item(1).getChildNodes();

          // Find out the request type (Reservation or Cancellation)
          String l_requestType = l_bookingType.item(0).getNodeValue();
          if(l_requestType.equalsIgnoreCase("RESERVATION")){

             ...
          }
          else if(l_requestType.equalsIgnoreCase("CANCELLATION")) {
            l_hotelID =
              Integer.parseInt(l_booking.item(0).getChildNodes().item(0).getNodeValue());
            String l_bookingNote  = l_booking.item(7).getChildNodes().item(0).getNodeValue();
            cancelRooms(l_hotelID, l_bookingNote); 
          }
        }
        l_bstream.close();    // Close the byte array stream
      }
    } catch(Exception ex) {  // Trap the Errors
       System.out.println("Error is "+ ex.toString());
       l_status="FINISH";
    }
  }

  public String dequeueMessage(AQQueue p_queue) {
    AQMessage                l_message=null;
    AQRawPayload             l_rawPayload;
    AQDequeueOption          l_deqOption;
    byte[]                   l_array;
    try {
      // Create a AQDequeueOption object with default options:
      l_deqOption = new AQDequeueOption();
      l_deqOption.setCorrelation("5810");
      // Dequeue a message:
      l_message = p_queue.dequeue(l_deqOption);
      // Retrieve raw data from the message:
      l_rawPayload = l_message.getRawPayload();
      l_array = l_rawPayload.getBytes();
      return  new String(l_array);
    } catch(Exception e) {     // Catch the exception
       System.out.println("Exception :"+ e.toString());
       return "Fail";
    }
  }

  public void service(HttpServletRequest p_request,
                      HttpServletResponse p_response)
                      throws ServletException, IOException {

    // Set parameters for the servlet response.
    p_response.setHeader("pragma","no-cache");
    p_response.setContentType("text/html");

    String l_reqType = p_request.getParameter("REQ_TYPE");
    String l_hotelID = p_request.getParameter("HOTEL_ID");

   if (l_reqType == null){
      ...
   } else if (l_reqType.equals("CHANGE_AVAILABILITY")){
      PrintWriter l_write = p_response.getWriter();
      p_response.setContentType("text/html");
      try{
        m_data = this.fetchAvailability(l_hotelID);
        // Build HTML form for entering new availability data.
        TPHSServletHTML.putChangeAvailPage(l_write, m_data, l_hotelID);
        l_write.close();   
      } catch(Exception ex){
        l_write.println(TPHSServletHTML.showErrorPage(ex.toString()));
      }
    } else if (l_reqType.equals("COMMIT_CHANGED_AVAIL")){
       PrintWriter l_write = p_response.getWriter();
       p_response.setContentType("text/html");
       try {
         m_updatedData = m_updatedData || this.commitChangedAvail(p_request);

         // Build HTML page to display status message.
         TPHSServletHTML.genMessagePage(l_write, m_message," ");
         l_write.close();   
       } catch(Exception ex){
         l_write.println(TPHSServletHTML.showErrorPage(ex.toString()));
       }

    ...

    } else if (l_reqType.equals("SEND_MAIL")) {
      PrintWriter l_write = new PrintWriter(p_response.getOutputStream());
      if(m_updatedData){
        m_updatedData = false;
        this.sendUpdatesMailToHRS();
        TPHSServletHTML.genMessagePage(l_write,m_message,"Show RAW XML data");
      } else {
        m_message="Mail can be sent only when you have updated "+
                  "hotel information.";
        TPHSServletHTML.genMessagePage(l_write, m_message," ");
      }
      l_write.close();      // close the writer object
    }

public void sendUpdatesMailToHRS(){
  // close Updates XML doc
  m_updatesMailDoc.endElement(m_mailRoot); 

  l_mailBody = m_updatesMailDoc.getXMLDocumentString();


  // Create an empty document.

  m_updatesMailDoc = createXMLRoot();
  // Send updates to the HRS via email.

  // MailHandler m_mailHandler
  m_mailHandler.sendMail(MailParams.s_hrsMailID,
                         MailParams.s_mailServerName,
                         l_mailBody);
  m_message = "Message sent to HRS Successfully.";
}

  public void sendMail(String p_userName, 
                       String p_hostName,
                       String p_messageBody){
    try{      
      java.util.Properties l_props = System.getProperties();
      l_props.put("mail.smtp.host", p_hostName);      
      Session l_session = Session.getDefaultInstance(l_props, null);

      MimeMessage l_message = new MimeMessage(l_session);
      l_message.setSubject("TPHS XML Updates");
      l_message.setText(p_messageBody);
      l_message.setRecipients(Message.RecipientType.TO,
                              InternetAddress.parse(p_userName));

      Transport.send(l_message);
    } catch (MessagingException ex){
       ex.printStackTrace();
    }
  }