How to Parse the Registration Reply

To parse the SC_REPLY XML message that the CRNP server sends in response to a registration or unregistration message, you need a RegReply helper class. You can construct this class from an XML document. This class provides accessors for the status code and status message. To parse the XML stream from the server, you need to create a new XML document and use that document's parse method. The JAXP documentation at http://java.sun.com/webservices/jaxp/ describes this method in more detail.

1. Create the Java code that implements the preceding logic.

   Note that the readRegistrationReply method uses the new RegReply class.

   private void readRegistrationReply(InputStream stream) throws Exception
   {
           // Create the document builder
           DocumentBuilder db = dbf.newDocumentBuilder();
           db.setErrorHandler(new DefaultHandler());
   
           //parse the input file
           Document doc = db.parse(stream);
   
           RegReply reply = new RegReply(doc);
           reply.print(System.out);
   }

2. Implement the RegReply class.

   Note that the retrieveValues method walks the DOM tree in the XML document and pulls out the status code and status message. The JAXP documentation at http://java.sun.com/webservices/jaxp/ contains more detail.

   class RegReply
   {
           public RegReply(Document doc)
           {
                   retrieveValues(doc);
           }
   
           public String getStatusCode()
           {
                   return (statusCode);
           }
   
           public String getStatusMsg()
           {
                   return (statusMsg);
           }
           public void print(PrintStream out)
           {
                   out.println(statusCode + ": " +
                       (statusMsg != null ? statusMsg : ""));
           }
   
           private void retrieveValues(Document doc)
           {
                   Node n;
                   NodeList nl;
                   String nodeName;
   
                   // Find the SC_REPLY element.
                   nl = doc.getElementsByTagName("SC_REPLY");
                   if (nl.getLength() != 1) {
                           System.out.println("Error in parsing: can't find "
                               + "SC_REPLY node.");
                           return;
                   }
   
                   n = nl.item(0);
   
                   // Retrieve the value of the statusCode attribute
                   statusCode = ((Element)n).getAttribute("STATUS_CODE");
   
                   // Find the SC_STATUS_MSG element
                   nl = ((Element)n).getElementsByTagName("SC_STATUS_MSG");
                   if (nl.getLength() != 1) {
                           System.out.println("Error in parsing: can't find "
                               + "SC_STATUS_MSG node.");
                           return;
                   }
                   // Get the TEXT section, if there is one.
                   n = nl.item(0).getFirstChild();
                   if (n == null || n.getNodeType() != Node.TEXT_NODE) {
                   // Not an error if there isn't one, so we just silently return.
                           return;
                   }
   
                   // Retrieve the value
                   statusMsg = n.getNodeValue();
           }
   
           private String statusCode;
           private String statusMsg;
   }