The parser can not load an imported schema within a schema document. I suspect the underlying Xerces is buggy as well as it does not work for both cases.

The files are attached. The properties should be changed to get the appropriate location for your setting. You can also find the related file in
http://javaweb.eng/~umit/jaxp12_bugs/test/ directory in importtestfails.

Here is an example of the run:

***********PARSER TEST importtestfails with Props file = /home/umit/projects/DTD2Schema/test/importtestfails/Properties

Schema Location: file:/home/umit/projects/DTD2Schema/test/importtestfails/Test1.xsd

Using JAXP schemaSource setting:

Location of Schema is: file:/home/umit/projects/DTD2Schema/test/importtestfails/Test1.xsd

Warning: URI=null
Line=-1: src-import.0: Failed to read imported schema document 'http://www.w3.org/2001/xml.xsd'.

Error: URI=null
Line=-1: src-resolve: Cannot resolve the name 'xml:lang' to a(n) attribute declaration component.

Error: URI=null
Line=-1: src-ct.0.1: Complex Type Definition Representation Error for type 'description'. Element 'attribute' is invalid, misplaced, or occurs too often.

Error: URI=file:/home/umit/projects/DTD2Schema/test/classes/../importtestfails/instance.xml
Line=8: cvc-complex-type.3.2.2: Attribute 'xml:lang' is not allowed to appear in element 'a'.

Tag <b> occurs 1 times
Tag <a> occurs 1 times
Tag <foobar> occurs 1 times
Tag <c> occurs 1 times

###@###.### 2002-02-27

One thing to add, I also tried "file" URIs in the import declaration and it fails to load as well.