- From: <noah_mendelsohn@us.ibm.com>
- Date: Mon, 22 Apr 2002 17:45:18 -0400
- To: reagle@w3.org
- Cc: bobatk@microsoft.com, ian@w3.org, w3c-ietf-xmldsig@w3.org, www-tag@w3.org, xml-dist-app@w3.org
SOAP adopts the QName type for many purposes, but generally depends on the value space, not the lexical space as being semantically interesting. From [2] (your reference): "The ·value space· of QName is the set of tuples {namespace name, local part}, where namespace name is an anyURI and local part is an NCName. The ·lexical space· of QName is the set of strings that ·match· the QName production of [Namespaces in XML]." So, the values of Qnames are indeed expanded names. In reviewing the latest SOAP editors drafts, I think this is a point that could be made more crisply (I'm cc:'ing distApp). Still, use of QName can be taken to imply the "expanded name", as that is the value space of QName. Of course, the lexical space uses prefixing, so use of the lexical space may depend on having a proper definition for the prefix in scope. ------------------------------------------------------------------ Noah Mendelsohn Voice: 1-617-693-4036 IBM Corporation Fax: 1-617-693-8676 One Rogers Street Cambridge, MA 02142 ------------------------------------------------------------------ Joseph Reagle <reagle@w3.org> Sent by: www-tag-request@w3.org 04/19/2002 11:26 AM Please respond to reagle To: ian@w3.org, www-tag@w3.org cc: bobatk@microsoft.com, w3c-ietf-xmldsig@w3.org, www-xkms@w3.org, (bcc: Noah Mendelsohn/Cambridge/IBM) Subject: Are QNames in Attribute Values Permitted as Identifiers? I'm noting that QNames are increasingly being used as identifiers within specifications. For example, XKMS is moving this way given the precedence set by SOAP, I'm seeing it in other ws-security work as well. My primary question is an architectural one: are these acceptable replacements for URIs as identifiers within our specifications? (They're certainly easier to read!) What is the identifier, the string "foo:bar" or the tuple [0]? Do we expect all specs to treat them uniformly in the next version of XML? What about present versions? My second question is an unfounded question about security implications. I haven't thought it through, but I wonder if there's any security ambiguities arising from the use of QNames as identifiers within an attribute value. When you sign a document via XML Canonicalization, it's attribute value is a string-value (not an "expanded-name" in XPath terminology, nor a QNAME in others'), but it also doesn't rewrite prefixes either so I feel safe. UDDI's schema-centric c14n [1] does rewrite namespace prefixes [2], but it's also schema centric -- I'm not sure what the result is there. (Bob?) And in other applications, where both sorts of processing might be done (attributes as strings versus QNAMEs) it's hard to say... [0] http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#QName [1] http://www.uddi.org/pubs/SchemaCentricCanonicalization-20020213.htm [2] http://lists.w3.org/Archives/Public/w3c-ietf-xmldsig/2002JanMar/0204
Received on Monday, 22 April 2002 18:01:30 UTC