XML Server Getting Started    

     } catch (e) { 

        util.messageBox("Login failed", e.description); 

     } 

   } 

The first characteristic element of the above code is the standard sequence of  Java statements related to receiving and parsing 

the input XML: 

      InputSource in = new InputSource(request.getInputStream()); 

      DOMParser parser = new DOMParser(); 

      parser.parse(in); 

      Node requestRoot = parser.getDocument().getDocumentElement(); 

Next is the way your code can apply XPath statements to  query  the document via XPathAPI: 

      XPathAPI xp = new XPathAPI(); 

       .    .    .   .   .   .  .   

      String userid = getNodeValue(xp.selectSingleNode(requestRoot, "//userid"));  

On the other hand, you can bypass XPathAPI class and use Xalan directly. 

And last, but not least, is the encoding of the `<', `&', and the quote characters, like in the following fragment: 

      StringBuffer sb = new StringBuffer(getStackTraceAsString(e)); 

      StringFunctions.replaceAll(sb, "&", "&"); 

      StringFunctions.replaceAll(sb, "<", "<"); 

      StringFunctions.replaceAll(sb, "\"", """); 

      result = "" + sb.toString() +  "" ; 

Remember, well formed XML should replace these characters with references to predefined entities `<', `&' and 

`"' correspondingly (that is   if presented inside so called  parsed character data . There is an alternative method   

declare a non parsed character or CDATA section.) 

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