Posted: October 11th, 2011 - So I nearly pulled out all my hair last night as I spent way to long trying to figure out why my simple xpath query was not working on an EPUB container xml file. No matter what I did my Coldfusion xmlsearch function kept returning an empty array. Turns out the issue was because the EPUB OCF specification uses a default namespace in its root element.

Of course, with it being my first time using the Coldfusion XmlSearch function and xpath none of the examples I looked at online, such as here had namespaces in them. Thus, I was unaware that an xpath string like "/container/rootfiles/rootfile" would not work on xml defined like the below:

Notice the xmlns attribute in the container tag. That tells the xml document that a namespace has been defined. According to my light reading namespaces in xml are often given a prefix. However, the OCF specification uses a default namespace so a prefix is not used. That means you just use a colon(:) like so "/:container/:rootfiles/:rootfile".

Quick thanks to the site below which lead my to solve and understand my issue:

http://www.talkingtree.com/blog/index.cfm/2005/11/18/XmlSearchNoNameNamespace