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My concern with the namespace recommendation is not its scope. My concern is its "coherence". That is, I am concerned that aspects of the specification are incongruent with other specifications upon which it depends. Confusion about the "meaning" of the namespace URI is symptomatic. This problem arises because, while the section cited by Mr. Gudgin below states quite clearly that "it is not a goal" that the URI's entail a retrieval sematics, many examples in the specification employs http URLs. This problem could be rectified. It could have been, and well still could be. Yet the parties with authority to undertake such matters dismiss all objections to the content of the specification as misconstruing. This perplexed me when the recommendation appeared two years ago. It continues to perplex me now. Why do the examples choose to use, as namespace identifiers, URIs which, according to the referenced rfc2396, are members of "the subset of URI that identify resources via a representation of their primary access mechanism." In particular, "http" URLs? Where the reader attempts to understand what an URI, or an URL, or an URN is, they may discover that, for example, the discussion of the syntax of a "common internet scheme syntax" for uniform resource locators in rfc1738 - a syntax to which "http" URLs conform - includes discussion such as that on the "url-path" component, whereby "the rest of the locator consists of data specific to the scheme, and is known as the "url-path". It supplies the details of how the specified resource can be accessed. ..." rfc2396 itself goes on to suggest that the respective "URI scheme defines the namespace of the URI, and thus may further restrict the syntax and semantics of identifiers using that scheme". It reiterates this notion where it discusses the "Scheme Component" and suggests that "the URI syntax consists of a sequence of components separated by reserved characters, with the first component defining the semantics for the remainder of the URI string." [It's their language, not mine.] Where the chosen URI scheme is "http", the reader might reasonably expect that the semantics described in the specification of the http URL scheme should apply. That is, as noted in section 3.2.2 of rfc2068, "the 'http' scheme is used to locate network resources via the HTTP protocol." That is, the intended use of this specific URI form is to retrieve a resource. Where the uninitiated reader is left to fill in the blanks, a reasonable supposition is that the resource might well be a schema. Even though this stands in contrast to the namespace recommendation's stated goals. Where the reader attempts to resolve this quandry by asking, "well, if it's not a schema, then what is it?" the situation deteriorates from bad to worse. This is not a happy situation, but what's a reader to do? The reader expects either that the namespace recommendation would acknowledge that the consequences of retrieval are at present not understood and therefore formulate examples to employ URI's which were not associated with a retrieval semantics, or that the namespace recommendation would describe the nature and use of the resource which is to be retrieved from locations for which a URL is specified, or, at least, that the namespace recommendation would say that the conformance of a document which incorporates URI's with a retrieval semantics is defined only in the context of an additional spec which does describe those retrieval semantics. The namespace recommendation adopts the semantics of URI's with respect to authorities in pursuit of the goal of ensuring uniqueness and persistence, but then ignores the retrieval semantics of the URL's which it uses to illustrate its concepts. This is incoherent. It leads to situations like the following Lisa Rein wrote: > > Greetings Uche: > ... > However, I probably gat asked that question from throughly puzzled > students more than anything else when I was teaching: "Where does the > the namespace URI go to?" (Um. Nowhere. I just looks like a URI. It > isn't one.) > Why doesn't it go anywhere? Could it go somewhere? (No. It could say > "ooga booga" and it would still work.) > Have I ever thought about maybe having it go somewhere?......(You get > the message) > Wouldn't it be easier to fix this? Issue a correction to REC-xml-names-19990114 in which the examples use only URI forms which entails only the minimal semantics which the recommendation can explain. If the implications of a specific URI form are not understood, then don't choose to use that URI form which will lead to questions which are unanswerable. Why is it better to repeatedly respond to the confusion which otherwise inevitably ensues? Martin Gudgin wrote: > > > > Most of the unfulfilling argument surrounding it springs from the > > > assumption that, since namespace names *look* like URLs, they should > *act* > > > like URLs -- that is, that one should be able to to point a Web Browser > > > at them and retrieve something useful since they look like something one > > > might point a Web Browser at. This assumption, while not unreasonable, > > > is explicitly disclaimed by the namespaces spec. > > > > Really? Where? > > Section 2[1] says: > > 'The namespace name, to serve its intended purpose, should have the > characteristics of uniqueness and persistence. It is not a goal that it be > directly usable for retrieval of a schema (if any exists).' > > I note from this that it only mentions retrieval of schemata but maybe it is > reasonable to extend the meaning of the statement to cover all resource > types. > > Whether this is the 'explicit disclaimer' that Jonathan meant only he can > confirm or deny. > > Martin Gudgin > DevelopMentor > > [1] http://www.w3.org/TR/REC-xml-names/#ns-decl
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