XML Server Getting Started    

XML objects in XMLSP scripting  

One of the specifics of XMLSP scripting is a heavy usage of XML objects as XML becomes 

de facto

 communication 

protocol across all tiers of the distributed system. This document does not attempt to cover all types of XML objects you may 

find useful while scripting XMLSP pages (see 

on line reference of XML Dom Objects/Interfaces at MSDN Library

). Instead, 

in this section we will focus on the most often used objects: XML Document, XML Node and XML Nodelist. 

XML Document objects are, strictly speaking, pointers to instances of 

DOMDocument interface

. Several methods of 

xmlapi

object (/xmlsp/htc/xmlapi.htc)    

XMLObject()

, 

XML(), XMLfromString(),  XMLHTTPRequest()

   are specifically provided as 

convenience methods all returning DOMDocument objects. Below we describe XMLObject(), XML() and 

XMLfromString(), while function XMLHTTPRequest() is explored in the separate section 

Accessing server side objects from 

the client code:  XML over HTTP calls.

Method 

XMLObject()

 simply returns pointer to a new DOMDocument interface. Method 

XML([url]) 

takes an optional 

argument to treat it as URL to synchronously load DOMDocument with XML stream returned by the URL. It may throw 

exception when the URL does not exist or returns non well formed XML. For examples, the following script will result in 

displaying the content of the entire XML document contained at  /Examples/controls.xml : 

var xmlDoc = xmlapi.XML("/Examples/controls.xml"); 

alert(xmlDoc.xml); 

Unlike method 

XML() 

which attempts to initialize XML document object with the data streamed out by URL, another 

method    

XMLfromString(xmlDocAsString)

 does it with script based string. This method also throws exception when the 

string does not contain a well formed XML.  

The most typical case of using 

XMLfromString()

 in XMLSP scripts is to package retrieval arguments along with the name of 

the connection pool into 

context

 object to be used by 

 in 

retrieve()

 and 

update()

 operations. For instance, in 

step0.jsp we have the following script to populating  customers  control: 

 function window::onLoad() { 

    customerList.connection =  asademo ; 

    customerList.retrieve(); 

 } 

which means passing  asademo  value as the name of the connection pool for XMLControl  customerList . This could have 

been changed to 

 function window::onLoad() { 

     customerList.context = xmlapi.XMLfromString("asademo"); 

     customerList.retrieve(); 

  } 

since when 

context

 property is not specified explicitly by the application, XMLControl builds one dynamically using 

connection

 value to populate 

currentsqlid

 node. Had we had to provide retrieval arguments, say to show only customers 

living in the state of New Jersey, we could have written something like: 

function window::onLoad() { 

    customerList.context = xmlapi.XMLfromString( 

"asademoNJ" 

    ); 

 2000 2002 Computer Technology Inc. All rights reserved. 

Page 11