Daffodil can run the standard XSD validator that is in Xerces.
We should also be able to provide schematron-based validation. This should allow use of a separate rule file (usually filename.sch extension), or schematron annotations embedded directly in the DFDL schema.
Note: the way schematron validation commonly works is that the schematron rules are converted into an XSLT, and the XSLT is run on the XML infoset to produce the schematron output. We can do this same thing, but should insure that the conversion from schematron rules into XSLT is part of schema compilation so that aspect is done once only, and the XSLT created from that has its corresponding Java "transformer" object created only once as well.