JAXB parser fails on multiple xsd files in same namespace

Question

I am having a problem with JAXB parsing a schema that imports 2 schema files from a similar namespace. Lets say we have 3 schema files A.xsd, B.xsd, and C.xsd as follows:
A: <xsd:schema xmlns:xsd="<http://www.w3.org/2001/XMLSchema> targetNamespace="A" xmlns="A" xmlns:z="Z" xmlns:jxb="<http://java.sun.com/xml/ns/jaxb> jxb:version="1.0" elementFormDefault="qualified"> <xsd:import namespace="Z" schemaLocation="B.xsd"/> <xsd:import namespace="Z" schemaLocation="C.xsd"/> </xsd:schema>
B: <xsd:schema xmlns:xsd="<http://www.w3.org/2001/XMLSchema> targetNamespace="Z" xmlns="Z" elementFormDefault="qualified"><xs:element name="BElement"></xs:element></xsd:schema>
C: <xsd:schema xmlns:xsd="<http://www.w3.org/2001/XMLSchema> targetNamespace="Z" xmlns="Z" elementFormDefault="qualified"> <xs:element name="CElement"></xs:element></xsd:schema>
The problem we have is that JAXB compiler fails during parsing and complains about an unresolved element (z:CElement) in the second schema (C.xsd) for the single namespace (Z). The complaint is reversed if we flip the order of the imported schema. The exact error is as follows: [ERROR] src-resolve: Cannot resolve the name 'z:CElement' to a(n) element declaration component.
So the question is, how do we get JAXB to permit the import of 2 or more elements that are defined in individual schema files that belong to the same namespace.
Thanks for your support,

Answer 1

Greg,
I believe that Xerces does not (and is not required to) parse anything other than the first <import> for a given namespace. I think what you are seeing is that Xerces is ignoring the second import for the "Z" namespace and therefore, the JAXB schema compiler is complaining that it can't resolve the element ref.
Others on this thread may have already covered these work arounds, but here goes:
1. you can disable JAXB's schema validation check by passing "-nv" to xjc or <arg value="-nv"/> to the ant task. This should allow XJC to get past the xerces behavior and generate proper code. In the current codebase, we are realying on some xerces internals to perform schema validation within XJC.
2. you might also be able to create another schema file, say Z.xsd, that <includes> all of your schemas belonging to that namespace. Then you can bring all of them in with a single <import> of Z.xsd in A.xsd.
I haven't tried it, but I think it'll work.
Greg, FYI we have a very active developer community on Java.net - that's the best place to post these kinds of questions. We (the JAXB team) don't monitor the developer forums as closely. Check it out:
http://jaxb.dev.java.net
and join the "users" interest list:
https://jaxb.dev.java.net/servlets/ProjectMailingListList
Thanks,
--Ryan Shoemaker, Sun Microsystems, Inc.