This is another version of a question which seems to come up perennially, but it seems to be slightly different than the versions I can find discussion of.
I am using Xerces-C to validate an XML file. The file uses a namespace, but does not describe where to find the schema (.xsd file) for the namespace. So before validating the file, I call fgXercesSchemaExternalSchemaLocation to give the names of the files containing the schemas for the namespaces that the XML file might use. So far, that works fine: Xerces locates the schema for the namespace that the XML file uses. The difficulty is that one of the schemas imports another schema. Xerces seems to demand that the first schema contain an <import> element, and that the <import> provide the file name containing the imported schema; the list provided to fgXercesSchemaExternalSchemaLocation seems to have no effect. Whereas I would assume that the fgXercesSchemaExternalSchemaLocation list would be consulted first to find the imported namespace, and the schemaLocation attribute of the <import> element would be ignored. In particular, section 4.2.3 of XML Schema Part 1 suggests that omitting the schemaLocation attribute is intended to leave it to the processor to determine how the find the schema, and in the context of Xerces, I would expect Xerces to consult the fgXercesSchemaExternalSchemaLocation list. But if I omit schemaLocation, I get errors like this: Error at file file:///home/dworley/sandbox-151/dir-local/share/sipxecs/schema/alias.xsd, line 54, char 54 Message: Schema Representation Constraint: Namespace 'http://www.sipfoundry.org/sipX/schema/xml/sip-00-01' is referenced without <import> declaration And note that the message is factually incorrect; there is an <import> element: <import namespace="http://www.sipfoundry.org/sipX/schema/xml/sip-00-01"; /> Dale
