API to validate a XML document from a schema in a WSDL file ?

Hello, 

I am looking for a way to validate the adequation of an XML document with a
schema in a WSDL file.

Is there an API providing all the tools to do that ?
Or is it necessary to extract in a first time the schema from the WSDL file
? And in this case, is there an API to execute this extraction, and an other
to do the checking ?

Thanks for your help.

Julien Thouand