I use your getURL, postURL,toXML, and xpath functions extensively. Good stuff. 

However, I ran into an odd problem that I was able to debug. This problem throws erros both DS and in xpath builder app. 

 In DS the my xml variable cannot be updated 

In xpath builder I get the following error Error :: Invalid XML/JSON format javax.xml.xpath.XPathExpressionException

 Anyways, it turns out that the problem occurs when an xml element looks like this 

 <element attribute="" attribute="" > 

 instead of 

 <element attribute="" attribute=""> 

No joke! This fixes the issue. I don't have to tell you that the first version is still valid XML and therefore your parser should not throw errors. Please let me know when this can be updated. Thank you. Note I fixed this by replacing " > with "> in my xmlStr before parsing.