How can XSLT and it's related technologies be used in implementing Web Services? For intance on a document based web service, let's assume there are "required" fields - is schematron "speedy" enough to use here in validating documents as they come in? What other uses might XSLT and it's related technologies have in developing web services (be they document or RPC based)?
XSLT is useful for transforming XML documents into something else (including a slightly different kind of XML document). With that in mind, I would say XSLT might be appropriate for implementing the service behind the SOAP interface.