Re: [xml] Id attribute detection in arbitrary namespace

[Daniel Veillard <veillard redhat com>]

On Sun, Aug 04, 2013 at 09:40:02PM +0400, Алексей Емельянов wrote:
> Hello.
>
> We discovered a problem with Id attribute detection, defined
> as a global attribute in some external schema.
>
> Here is an example:
>
> <soapenv:Envelope
>    xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/";
>
> xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd";
>
> xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd";>
>    <soapenv:Header>
>       <wsse:Security>
>          <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#";>
>             <ds:SignedInfo>
>                <ds:Reference URI="#body"></ds:Reference>
>             </ds:SignedInfo>
>             <ds:SignatureValue/>
>             <ds:KeyInfo>
>               <ds:KeyName/>
>             </ds:KeyInfo>
>          </ds:Signature>
>       </wsse:Security>
>    </soapenv:Header>
>    <soapenv:Body wsu:Id="body"></soapenv:Body>
> </soapenv:Envelope>
>
> Attribute "wsu:Id" is not detected as an Id attribute,
> because libxml2 knows nothing about its type,
> defined in wss-wssecurity-utility-1.0.xsd:
>
> <!-- // Global attributes // -->
> <xsd:attribute name="Id" type="xsd:ID">
>   <xsd:annotation><xsd:documentation>
>     This global attribute supports annotating arbitrary
>     elements with an ID.
>   </xsd:documentation></xsd:annotation>
> </xsd:attribute>
>
> As a result any library, such as xmlsec as an example,
> cannot process such documents using "id()"
> XPath expression.
>
> Function xmlIsID can use DTD for Id detection,
> but DTD does not allow to describe
> the global attributes.
>
> Is there known solution for this issue?

Don't bury the knowledge of the IDness in an external schemas:

  http://www.w3.org/TR/xml-id/

name your id xml:id, libxml2 will detect automatically , the spec
has been around for 8 years, and libxml2 implements it since then.

Daniel

-- 
Daniel Veillard      | Open Source and Standards, Red Hat
veillard redhat com  | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | virtualization library  http://libvirt.org/