I'm trying to read and parse and XML document uploaded by the user.  What's the recommended way of doing it?  

Should I just use the built-in XML library, or try and use the outdated XML Records extension from the Forge?
What do you mean "outdated" ?

XML Records works on all supported OutSystems Platform versions and in all stacks.

I would recommend investing the time to use XML Records.
Hi Jared Tan,

Prepare structure of your XML document. Structure must be nested properly i.e. All nodes and subnodes must go at proper places. Structure attributes names must match with your XML document(Case sensitive). Then pass the XML document to "XMLToRecordList" control. Pass your root structure to the same control converted into object. You will get all XML values into the structure.

Else you can go for built-in XML library.

I hope this helps.

Best Regards,
Suraj Borade

I was having issues getting it deployed to my environment.  Solved them now.