XML Demystified

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XML Demystifi ed
You’ll notice that the XML document refers to the catalog.dtd. As you’ll recall
from Chapter 3, a DTD file contains the document type definition that defines the
markup tags that can be used in the XML document and specifies the parent-child
structure of those tags. The XML parser references the DTD when parsing elements
of the XML document.
Create a DTD for this example. You do this by writing the following information
into a file and saving the file as catalog.dtd in the directory that contains the catalog
.xml file.
The final step you’ll take to prepare to learn MSXML is to create the HTML file
that contains the JavaScript used to access the catalog.xml document. The HTML
file follows. Some of it is familiar because it’s HTML. Other parts, you’ll understand
if you know JavaScript (don’t worry if you don’t understand them; we explain
JavaScript throughout this chapter). However, the portions of the HTML file that
use MSXML are probably confusing, even if you previously worked with
JavaScript.
For now, simply create this HTML file and save it to a file called default.html in
the directory where you saved catalog.xml and catalog.dtd. We explain each part of
the HTML file throughout this chapter.
var objXML;
function LoadDocument()
{
var inputfile = document.all("inputfile").value;
objXML = new ActiveXObject("MSXML2.DOMDocument.4.0");
objXML.async = false;
objXML.load(inputfile);
if (objXML.parseError.errorCode != 0)
{
alert("Error loading input file: " + objXML.parseError.reason);
return;
}
document.all("xmldoc").value = objXML.xml;
}