[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [Elist Home]
Subject: [entity-resolution-comment] uri vs. system confusion
Hi All, In working to develop a robust xml catalog system for Debian that's consistent with the OASIS XML Catalogs spec, I find that I'm still a bit confused about the distinction between the uri-based elements and the system-based elements. To get to the point: The spec doesn't clearly explain the distinction between the two, and, furthermore, doesn't provide any usage recommendations. For example, here are a couple related points/questions: A. The <rewriteURI> example given in 4.3 implies that not only is the prefix rewritten, but also that the intended document/entity is also included in the 'rewritePrefix' attribute. Put another way, the _complete_ URI is rewritten, and not just the prefix. If this is indeed the intended usage, perhaps the 'rewritePrefix' attribute should be changed to 'rewriteURIString' or something of the sort. B. Given Paul Grosso's response (below) to a similar inquiry, another implied usage is IMO that SYSTEM Ids get remapped _only_ via a <rewriteSystem> element, and never via the <rewriteURI> element. (This despite the fact that all system identifiers are URIs.) Is this the intended usage? If so, a clarification in the spec on this point would be very helpful. In discussions with fellow Debian XML/SGML developers, I find that this is a common source of confusion when attempting to grok the XML Catalogs spec in all its fullness:) C. In 4.2 of the spec, the opening paragraph states: "Other URI references, for example namespace names, stylesheets, included files, graphics, and hypertext references, simply identify other resources. The input to a resolver that locates resources is simply the original URI reference." I find this confusing, as well. For example, to remap the URI that identifies a file within the current DocBook XSL stylesheet, I'd want to use <rewriteSystem .../> to point to the local filesystem like so: <rewriteSystem systemIdStartString="http://docbook.sourceforge.net/release/xsl/current/" rewritePrefix="file:///usr/share/sgml/docbook/stylesheet/xsl/nwalsh/"/> rather than using <rewriteURI.../>. But the text of the paragraph implies that <rewriteURI.../> should be used. Does the reason for using <rewriteURI.../> have something to do with the fact that the stylesheet URI does NOT appear in the XML document, and is therefore not restricted by the ExternalID as SystemLiteral constraint as per the XML spec? Again any clarification here would be greatly appreciated... FWIW, I recently joined the Entity Resolution TC (hence a prospective member), so I'll continue to request that the spec clarify these, and related issues - even if I can't yet cast a vote :-) Thanks, Mark ====================================================================== Paul Grosso's response of Mon, 28 Oct 2002 [1] to an older message that Norm reposted: David Brownell: >> - I really don't see any need to have both the "uri" and >> "systemId" sets of elements. Paul's response: "The use of systemId is expressly to model production [75], ExternalID, of the XML spec. This seems like good architecture to me. XML has no concept of a URI. It only has a concept of ExternalID with a SystemLiteral." ====================================================================== [1] http://lists.oasis-open.org/archives/entity-resolution/200210/msg00013.html -- _____________________________________ Mark Johnson <mark@dulug.duke.edu> Debian XML/SGML <mrj@debian.org> Home Page: <http://dulug.duke.edu/~mark/> GPG fp: 50DF A22D 5119 3485 E9E4 89B2 BCBC B2C8 2BE2 FE81
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [Elist Home]
Powered by eList eXpress LLC