In OSx, you can rely on the libxml package, which includes xmllint. You will call this on a command line, it's fast and reliable.
Wednesday, July 17, 2013
A couple of example:
To validate a xml file:
xmllint --noout yourxmlfile.xml
To validate a xml file against a schema:
xmllint --noout --schema yourxsdfile.xsd yourxmlfile.xml