Introduction

• MSXML, the Microsoft XML parser included in Internet Explorer 5.0 ,includes full support for the programming interfaces described in the W3C Document Object Model Core (Level 1) recommendation.
• MSXML also adds Microsoft specific functionality.
• MSXML parse an XML document to a tree.  DOM supports classes (data types) and methods to access the manipulate the tree.
• References:
• Microsoft's DOM User Guide: http://msdn.microsoft.com/isapi/msdnlib.idc?theURL=/library/psdk/xmlsdk/xmls6g53.htm
• W3C XML Specification: http://www.w3.org/XML/
• W3C Document Object Model (DOM) Level 1 Specification: http://www.w3.org/TR/REC-DOM-Level-1/

<%
   Set objXML = Server.CreateObject("Microsoft.XMLDOM")
   objXML.async = False                 ' optional
   objXML.validateOnParse = False       ' optional
   objXML.Load(Server.MapPath("scriptingNews.xml"))
%>

Notes:

1. Server.CreateObject("Microsoft.XMLDOM") returns an XMLDOMDocument object, representing the entire XML document.
2. The async property may be set to false so that future loading will not be asynchronous.  The next statement will wait until the loading is completed.
3. The validateOnParse property may be set to false to disable DTD validation.  This will speed up the parsing.
4. MapPath performs mapping of file name of virtual directory to physical directory file name.

XMLDOMDocument Object

• XMLDOMDocument represents the top level of the XML source.
• Contains properties and methods to navigate, query, and modify the content and structure of an XML document.
• Since an XMLDOMDocument Object is also an XMLDOMNode, all methods of XMLDOMNode are available.
• Important properties and methods:
• documentElement: contains the root element of the document.
• load: Loads an XML document from the specified location, a file name or an url.
• loadXML: Loads an XML document using the supplied string.
• validateOnParse: Indicates whether the parser should validate this document.

• The XMLDOMNode object extends the core XML DOM node interface to provide support for data types, namespaces, DTDs, and schemas.
• Important properties and methods:
• attributes: the list of attributes for this node, an XMLDOMNamedNodeMap object.
• childNodes: a node list containing the children, an XMLDOMNodeList object.
• dataType: specifies the data type for this node: NODE_ATTRIBUTE, NODE_ELEMENT, NODE_TEXT, etc.
• firstChild: contains the first child of this node.
• getElementsByTagName: returns a collection of elements that have the specified name, an XMLDOMNodeList object.
• hasChildNodes: Returns true if this node has children.
• lastChild: Returns the last child node.
• nextSibling: Contains the next sibling of this node in the parent's child list.
• nodeName: Contains the qualified name of the element, attribute, or entity reference, or a fixed string for other node types.
• nodeType: Specifies the XML DOM node type, which determines valid values and whether the node can have child nodes.
• nodeValue: Contains the text associated with the node.
• parentNode: Contains the parent node (for nodes that can have parents).
• selectNodes: Applies the specified pattern-matching operation to this node's context and returns the list of matching nodes.
• text: Contains the text content of the node and its subtrees.
• There are many node types.  The most important are:
• NODE_ELEMENT: may contain attributes and children.
• NODE_ATTRIBUTE: represent an attribute of an element node.

For the parsed XML document with top elements <news>:

<news>
      <article id="_6337363">
         <headline_text>CDnow: Harbinger of E-Commerce Doom?</headline_text>
         <source>Industry Standard</source>
         <media_type>text</media_type>
         <cluster>E-commerce news</cluster>
         <tagline> </tagline>
         <document_url>http://www.thestandard.com/news/grok/</document_url>
         <harvest_time>Mar 30 2000 10:23PM</harvest_time>
         <access_registration> </access_registration>
         <access_status> </access_status>
      </article>
      <article id="_6336605">
        <headline_text>Tommy Hilfiger And Bluefly Settle Suit</headline_text>
         <source>Gomez</source>
         <media_type>text</media_type>
         <cluster>E-commerce news</cluster>
         <tagline> </tagline>
         <document_url>http://www.gomez.com/features/gomezwire.cfm?topcat_id=0&amp;section=ALL</document_url>
         <harvest_time>Mar 30 2000  9:58PM</harvest_time>
         <access_registration> </access_registration>
         <access_status> </access_status>
      </article>
</news>

To list all headline texts:

Method #1:

Set objLst = objXML.getElementsByTagName("article")
For i = 0 to (objLst.length - 1)
    strHeadline = objLst.item(i).getElementsByTagName("headline_text").item(0).childNodes(0).nodeValue
    Response.write "News item #" & (i+1) & ": " & strHeadline & "<BR>" & vbCRFL
Next

Method #2 (not so good):

Set objLst = objXML.getElementsByTagName("article")
For i = 0 to (objLst.length - 1)
    strHeadline = objLst.item(i).childNodes(0).text
    Response.write "News item #" & (i+1) & ": " & strHeadline & "<BR>" & vbCRFL
Next

Method #3:

Set objLst = objXML.getElementsByTagName("headline_text")
i = 0
For each objNode in objLst
    strHeadline = objnode.text
    i = i + 1
    Response.write "News #" & i & ": " & strHeadline & "<BR>" & vbCRFL
Next

XMLDOMNodeList Object

• The XMLDOMNodeList object supports iteration through the live collection, in addition to indexed access.
• ChildNodes and getElementsByTagName return an XMLDOMNodeList object.
• A live collection means any change to the collection is immediate.
• All collection methods can be used.
• Properties and methods:
• item: allows random access to individual nodes within the collection.
• length: indicates the number of items in the collection.
• nextNode: used as an iterator to return the next node in the collection.
• reset: Resets the iterator.

• An XMLDOMNamedNodeMap object is returned by the attributes property.
• Unlike an XMLDOMNodeList object, an XMLDOMNamedNodeMap can also be accessed by name.
• This is because attributes are uniquely identified by their names.
• In addition to the properties and methods for an XMLDOMNodeList object, an XMLDOMNamedNodeMap object also has the following properties and methods, among others:
• getNamedItem: Retrieves the attribute with the specified name.
• removeNamedItem: Removes an attribute from the collection.

To print all id attributes of attribute elements.

Set objLst = objXML.getElementsByTagName("article")
For i = 0 to (objLst.length - 1)
    strId = objLst.item(i).attributes.getNamedItem("id").nodeValue
    Response.write "News #" & i & " id: " & strId & "<BR>" & vbCRLF
next