[relaxng-user] Embedding HTML in a document: 'foreign-nodes' versus namespaces

[Nicholas Hemley]

Hello,

I am trying to allow HTML content within nodes of documents used in a
Java/XML application and have therefore used a 'foreign-nodes'
declaration in a Relax NG schema which is then converted to XML Schema
(since the app server only uses XML Schema) using the Jing utility:

Relax NG Schema [snippet]
...
define name="element-choice">
    <element name="choice">
      <zeroOrMore>
        <ref name="element-choice-title"/>
      </zeroOrMore>
      <zeroOrMore>
--> here is the usage:        <ref name="foreign-nodes"/>
      </zeroOrMore>
    </element>
  </define>
...
<define name="foreign-elements">
    <zeroOrMore>
      <element>
        <anyName/>
        <ref name="anything"/>
      </element>
    </zeroOrMore>
  </define>
  <define name="anything">
    <zeroOrMore>
      <choice>
        <element>
          <anyName/>
          <ref name="anything"/>
        </element>
        <attribute>
          <anyName/>
        </attribute>
        <text/>
      </choice>
    </zeroOrMore>
  </define>
  <define name="foreign-attributes">
    <zeroOrMore>
      <attribute>
        <anyName/>
      </attribute>
    </zeroOrMore>
  </define>
  <define name="foreign-nodes">
    <zeroOrMore>
      <choice>
        <text/>
        <ref name="foreign-attributes"/>
        <ref name="foreign-elements"/>
      </choice>
    </zeroOrMore>
  </define>

And here is a snippet of the generated XML Schema:

XML Schema [snippet - generated]
...
<xs:group name="foreign-elements">
    <xs:sequence>
      <xs:any minOccurs="0" maxOccurs="unbounded"
processContents="skip"/>
    </xs:sequence>
  </xs:group>
  <xs:group name="anything">
    <xs:sequence>
      <xs:any minOccurs="0" maxOccurs="unbounded"
processContents="skip"/>
    </xs:sequence>
  </xs:group>
  <xs:attributeGroup name="anything">
    <xs:anyAttribute processContents="skip"/>
  </xs:attributeGroup>
  <xs:attributeGroup name="foreign-attributes">
    <xs:anyAttribute processContents="skip"/>
  </xs:attributeGroup>
  <xs:group name="foreign-nodes">
    <xs:sequence>
      <xs:group minOccurs="0" maxOccurs="unbounded"
ref="foreign-elements"/>
    </xs:sequence>
  </xs:group>
  <xs:attributeGroup name="foreign-nodes">
    <xs:attributeGroup ref="foreign-attributes"/>
  </xs:attributeGroup>
...

Firstly, is this schema correct? Could someone explain why it has
created a group and attributeGroup with the same name?

When I try and view the XML through my application I get the following
error reported:

Root cause follows.
com.sun.msv.verifier.jarv.FactoryImpl$WrapperException: reference to
the undefined attribute group: "foreign-attributes"

My question is therefore this: is the problem with how Jing has
converted the schema or my initial schema?

My other question is this: can I use namespaces instead of a
'foreign-nodes' declaration to achieve the same aim?

Fire those knowledge arrows at me!

Cheerio,
Nic.


Nic Hemley

Lothian NHS Webmaster & Developer

internal: 89240
external: 0131 536 9240
int'l: +00 44 131 536 9240
web: www.nhslothian.scot.nhs.uk


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