Hello,
you can simply produce your xml and it's schema,(the schema saves in a XSD file not XML)
Code:
objDataSet.WriteXml("C:\\...\\file.xml");//your XMLFile
objDataSet.WriteXmlSchema("C:\\...\\schema.xsd");//your Schema
if you encounter some errors about access control you should change the permissions and roles of your user where you make your result files.
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Mehdi.:)