How to validate XML with multiple namespaces in Python?

I'm trying to write some unit tests in Python 2.7 to validate against some extensions I've made to the OAI-PMH schema: http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd

The problem that I'm running into is business with multiple nested namespaces is caused by this specification in the above mentioned XSD:

<complexType name="metadataType">
    <annotation>
        <documentation>Metadata must be expressed in XML that complies
        with another XML Schema (namespace=#other). Metadata must be 
        explicitly qualified in the response.</documentation>
    </annotation>
    <sequence>
        <any namespace="##other" processContents="strict"/>
    </sequence>
</complexType>

Here's a snippet of the code I'm using:

import lxml.etree, urllib2

query = "http://localhost:8080/OAI-PMH?verb=GetRecord&by_doc_ID=false&metadataPrefix=nsdl_dc&identifier=http://www.purplemath.com/modules/ratio.htm"
schema_file = file("../schemas/OAI/2.0/OAI-PMH.xsd", "r")
schema_doc = etree.parse(schema_file)
oaischema = etree.XMLSchema(schema_doc)

request = urllib2.Request(query, headers=xml_headers)
response = urllib2.urlopen(request)
body = response.read()
response_doc = etree.fromstring(body开发者_如何转开发)

try:
    oaischema.assertValid(response_doc)
except etree.DocumentInvalid as e:
     line = 1;
     for i in body.split("\n"):
        print "{0}\t{1}".format(line, i)
        line += 1
     print(e.message)

I end up with the following error:

AssertionError: http://localhost:8080/OAI-PMH?verb=GetRecord&by_doc_ID=false&metadataPrefix=nsdl_dc&identifier=http://www.purplemath.com/modules/ratio.htm
Element '{http://www.openarchives.org/OAI/2.0/oai_dc/}oai_dc': No matching global element declaration available, but demanded by the strict wildcard., line 22

I understand the error, in that the schema is requiring that the child element of the metadata element be strictly validated, which the sample xml does.

Now I've written a validator in Java that works - however it would be helpful for this to be in Python, since the rest of the solution I'm building is Python based. To make my Java variant work, I had to make my DocumentFactory namespace aware, otherwise I got the same error. I've not found any working example in python that performs this validation correctly.

Does anyone have an idea how I can get an XML document with multiple nested namespaces as my sample doc validate with Python?

Here is the sample XML document that i'm trying to validate:

<?xml version="1.0" encoding="UTF-8"?> 
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/
     http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
  <responseDate>2002-02-08T08:55:46Z</responseDate>
  <request verb="GetRecord" identifier="oai:arXiv.org:cs/0112017"
       metadataPrefix="oai_dc">http://arXiv.org/oai2</request>
  <GetRecord>
   <record> 
    <header>
      <identifier>oai:arXiv.org:cs/0112017</identifier> 
      <datestamp>2001-12-14</datestamp>
      <setSpec>cs</setSpec> 
      <setSpec>math</setSpec>
    </header>
    <metadata>
      <oai_dc:dc 
     xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" 
     xmlns:dc="http://purl.org/dc/elements/1.1/" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ 
     http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
    <dc:title>Using Structural Metadata to Localize Experience of 
          Digital Content</dc:title> 
    <dc:creator>Dushay, Naomi</dc:creator>
    <dc:subject>Digital Libraries</dc:subject> 
    <dc:description>With the increasing technical sophistication of 
        both information consumers and providers, there is 
        increasing demand for more meaningful experiences of digital 
        information. We present a framework that separates digital 
        object experience, or rendering, from digital object storage 
        and manipulation, so the rendering can be tailored to 
        particular communities of users.
    </dc:description> 
    <dc:description>Comment: 23 pages including 2 appendices, 
        8 figures</dc:description> 
    <dc:date>2001-12-14</dc:date>
      </oai_dc:dc>
    </metadata>
  </record>
 </GetRecord>
</OAI-PMH>

---

Found this in lxml's doc on validation:

>>> schema_root = etree.XML('''\
...   <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
...     <xsd:element name="a" type="xsd:integer"/>
...   </xsd:schema>
... ''')
>>> schema = etree.XMLSchema(schema_root)

>>> parser = etree.XMLParser(schema = schema)
>>> root = etree.fromstring("<a>5</a>", parser)

So, perhaps, what you need is this? (See last two lines.):

schema_doc = etree.parse(schema_file)
oaischema = etree.XMLSchema(schema_doc)

request = urllib2.Request(query, headers=xml_headers)
response = urllib2.urlopen(request)
body = response.read()
parser = etree.XMLParser(schema = oaischema)
response_doc = etree.fromstring(body, parser)