In trying to convert over several HTML pages to the DITA XML format, James Edwards came up against a problem involving recursion:

But a problem I came across several times was the sheer complexity of recursive element conversion '" <code> becomes <jsvalue> (or one of a dozen similar elements), <a> becomes <xref> '¦ and that's all simple enough; but each of these elements might contain the other, or further child elements like <em>, and as we walk through the DOM so the incidence of potential recursion increases, until it gets to the point where my brain explodes.

His solution involves working with both regular expressions and document fragments. He loads the node he wants to work with, its parsed to prepare it and is passed off to do the "text-based mangling" to update it. The result is them pushed back into an XML object (fragment) and this is pushed back into the main document with a replaceChild call.

Alejandro Gervasio has finished up his series on DevShed looking at working with the DOM extension in PHP5 with this new article, a look at parsing child nodes.

In this last chapter of the series, I'm going to teach you how to handle the child nodes of an XML document by way of two simple methods, called hasChildNode() and removeChild() respectively. So let's not waste any more time in preliminaries and learn how to use them in a helpful way.

They review some of the concepts mentioned previously before moving ahead to the use of the hasChildNodes and removeChild methods to check for children and get rid of only certain ones.

DevShed continues their series about working with XML in PHP's DOM extension with this new tutorial posted today showing how to get at attributes for tags and cloning nodes from others.

You've probably realized that the DOM XML library can be pretty useful when working with web documents. However, this extension includes some other methods, which can be utilized to parse attributes of a given XML string, as well as to clone nodes.

They show how to use the getAttributes method, hasAttribue method and cloneNode method to work with their XML examples.

DevShed continues their series looking at using the DOM extension in PHP5 to work with XML in your application. They've already looked at adding attributes and creating CDATA information in a new DOM document. This time they build on that and also include new methods - appending comment nodes and getting at XML nodes by their IDs.

I'm talking about the DOM XML extension, which allows you to handle XML documents by using the DOM API. Thus, if you're interested in learning how to put this extension to work for you quickly, look no further, because you've come to the right place. [...] In this third installment of the series, I'll be teaching you specifically how to append comment nodes to a given XML string and how to extract certain elements via their IDs.

They review the method to add attributes and CDATA to an XML document first. Then they cover the other two new topics - appending comment nodes and grabbing nodes by their ID attribute.

Builder.com as posted a quick tutorial on working with the DOM functionality in PHP to create a dynamic XML document (Doctype and all).

Over the course of this article, I'll be introducing you to the main functions in this API, showing you how to programmatically generate a complete well-formed XML document from scratch and save it to disk.

They start off with creating the Doctype declaration before actually adding the content into the file (elements and text nodes), adding some attributes to the nodes, putting CDATA blocks inside them, and pushing out the results on the other side to be saved to a local "order.xml" file.

You can also download this article if you'd like to work with it (and its included PHP files) on your own.

Alright power PHP users out there, Adam Trachtenburg has a little quiz for you to see how much you know about working with the DOM in PHP.

Here's a question based on a recent PHP bug report which shows why DOM is fun. [...] But how do you retrieve it (the namespace URI of the root node) using DOMElement::GetAttributeNS()? What are the two magical input parameters to coax that value out?

The code is simple, but it's an interesting problem - anyone have any answers?