External schemas must be accessible to the application server on the SAS middle tier when you generate Web services that contain data sources or targets that reference those schemas.

If the schemas are not accessible, you can receive an error message similar to the following in the response from the Web services:

<fault:Fault code="4000" xmlns:fault="http://support.sas.com/xml/namespace/biwebservices/webservicemaker-9.2">
   <fault:Exception message="com.sas.web.services.maker.WSGenerationException: Unable to retrieve schema for 'instream' data source.">
      <fault:Exception message="java.io.FileNotFoundException: /C:/<Path>/<Schema> (A file or directory in the path name does not exist.)"/>
   </fault:Exception>
</fault:Fault>