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Subject: RE: [ws-rx] NEW ISSUE: XML Namespace URIs
Rich, So, you're going to parse the namespace and determine that a namespace that is a different namespace is indeed backwardly compatible? That makes no sense. When two namespace URI are different, then there is no conclusion that you can draw but that they are two distinctly separate namespaces. If you want to include version information, then it should NOT be in the namespace name but somewhere else, such as a version attribute on the schema or carried in the instance itself ala XSLT. A namespace is a space of names. Its purpose is to disambiguate between a token in one namespace and the same token in another namespace. Quoting the Namespaces in XML spec: We envision applications of Extensible Markup Language (XML) where a single XML document may contain elements and attributes (here referred to as a "markup vocabulary") that are defined for and used by multiple software modules. One motivation for this is modularity; if such a markup vocabulary exists which is well-understood and for which there is useful software available, it is better to re-use this markup rather than re-invent it. Such documents, containing multiple markup vocabularies, pose problems of recognition and collision. Software modules need to be able to recognize the tags and attributes which they are designed to process, even in the face of "collisions" occurring when markup intended for some other software package uses the same element type or attribute name. These considerations require that document constructs should have universal names, whose scope extends beyond their containing document. This specification describes a mechanism, XML namespaces, which accomplishes this. [Definition:] An XML namespace is a collection of names, identified by a URI reference [RFC2396], which are used in XML documents as element types and attribute names. XML namespaces differ from the "namespaces" conventionally used in computing disciplines in that the XML version has internal structure and is not, mathematically speaking, a set. These issues are discussed in "A. The Internal Structure of XML Namespaces". Just because a schema has a target namespace doesn't mean that when you change that schema that you should or must change its namespace. Cheers, Christopher Ferris STSM, Emerging e-business Industry Architecture email: chrisfer@us.ibm.com blog: http://webpages.charter.net/chrisfer/blog.html phone: +1 508 377 9295 Rich Salz <rsalz@datapower.com> wrote on 07/14/2005 03:45:35 PM: > > Chris indicated to the editors earlier that he preferred to > > use a date stamp to indicate version. You'll have to ask him about his > > reasons for this preference. I don't care one way or another. > > I care. Date-based version numbers have no explicit interop semantics. > There's a long history of major/minor semantics. Cf SAML 1.0, 1.1, and 2.0 > > /r$ > > -- > Rich Salz Chief Security Architect > DataPower Technology http://www.datapower.com > XS40 XML Security Gateway http://www.datapower.com/products/xs40.html >
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