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>XMLCast Introduction
>Parsing the XML
>Output as [simple]HTML
>Output as RSS
>Output as WML

Content Management and Distribution Using XML

Parsing the XML

It seems like every language has a different way of parsing XML. Microsoft's implementation is one of the better ones we've found. It allows for retrieval of node lists, the number of child nodes per node, and logical data extraction, to name a few. With this we've managed to walk through our XML tree and get all the data we want with a simple for loop. To keep our code organized, we've created a class for our articles:
Class xArticle Public Heading Public Link Public Summary Public Paras() End Class This simple class houses each part of our article as a public variable. That way, we can use an array and fill it with all of our article classes as we parse the XML, so when we want to output it, it's in a nice, easy-to-extract format. But before we send our XML news document to our parsing function, we pull out the non-repeating data out with the convenient .selectSingleNode method: ' Get the non-article data from the XML Document Set sLogo = XMLDoc.selectSingleNode("NEWS/LOGO") sLogo = sLogo.text Set sDate = XMLDoc.selectSingleNode("NEWS/DATE") sDate = sDate.text Now we need to go through the rest of the XML and pull out our article data. Here's the ParseXML function:

ParseXML function

Private Sub ParseXML(oXMLDoc) ' This is the main XML parsing function. ' It creates a new Article object with the appropriate data ' and fills an array (arArticles) with the objects Dim XMLNodes ' Article Nodes Dim XMLCNodes ' Article Child Nodes Dim arPara() ' Array for paragraphs ' Get all the <ARTICLE> nodes Set XMLNodes = oXMLDoc.getElementsByTagName("ARTICLE") Dim XMLPNodes ' Paragraph Nodes Dim i ' generic counter For i = 0 to (XMLNodes.length - 1) ' cycle through articles iACtr = i + 1 ' increment article counter ReDim Preserve arArticles(iACtr) Set arArticles(iACtr) = New xArticle ' create a new article object ' get article child nodes Set XMLCNodes = XMLNodes.item(i).childNodes Dim j For j = 0 to (XMLCNodes.length - 1) Select Case XMLCNodes.item(j).nodeName Case "HEADING" arArticles(iACtr).Heading = XMLCNodes.item(j).text Case "LINK" arArticles(iACtr).Link = XMLCNodes.item(j).text Case "SUMMARY" arArticles(iACtr).Summary = XMLCNodes.item(j).text Case "PARAGRAPHS" Set XMLPNodes = XMLCNodes.item(j).childNodes Dim p ' paragraph counter For p = 0 to (XMLPNodes.length - 1) ReDim Preserve arPara(p+1) arPara(p+1) = XMLPNodes.item(p).text Next ' p arArticles(iACtr).Paras = arPara End Select Next ' j Next ' i End Sub This function is run no matter what output is chosen. All we're doing here is walking through the XML tree, creating a new Article class for every article in the XML news document, setting the variables to the appropriate data, and storing it in a global arArticles array. There are about as many ways to walk an XML tree as there are DTDs, so we chose one of the simpler methods of using a For loop based on the NodeList.length() property. We set a variable called XMLNodes to a node list returned by .getElementsbyTagName passing in "ARTICLE". What we end up with is a node list of all the ARTICLE nodes. Since the rest of our data is child nodes of ARTICLE, we can loop through the node list, pulling data out (via .text) of the XML document and putting it into the public variables of our class when we run across a .nodeName we want. When we find a nodeName called "PARAGRAPHS", we do a nested loop to insert each paragraph into an array called arPara, which we set to the Paras() array in our class so we can output any number of paragraphs as called for. And that's all the XML magic we need. Now that we've got the data, let's format it.

Next: Output as [simple]HTML


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