- From: John Erickson <olyerickson@gmail.com>
- Date: Thu, 11 Mar 2010 19:39:31 -0500
- To: Linked Data community <public-lod@w3.org>
Nathan <nathan@webr3.org> wrote: >>>> Is it correct that all representations must have consistent fragment identifiers in order to be considered equivalent? >>> A fragment identifier should not identify different things in different representations. (Though it may be unrepresented in some or all of the representations.) >From http://www.w3.org/TR/webarch/#frag-coneg , the fragment identifier must be defined consistently by the representations; the *provider* decides when definitions of fragment identifier semantics are "sufficiently consistent..." >> If I recall correctly the URI RFC..., the semantics of fragments identifiers depends on the retrieved content-type. So why would they *have* to identify the same thing? >From http://www.w3.org/TR/webarch/#frag-coneg , "Individual data formats may define their own rules for use of the fragment identifier syntax for specifying different types of subsets, views, or external references that are identifiable as secondary resources by that media type." >> That being said, I agree it sounds like a good practice. Especially if you consider an RDF/XML and a Turtle representation of the same RDF graph... If their fragment identifier were not consistent, that would be a serious headache... But is this rule written somewhere? The interpretation in http://www.w3.org/TR/webarch/#frag-coneg suggests that it would be correct either for the fragment identifier to be interpreted by the RFG/XML and Turtle representations consistently --- refers to a semantically consistent secondary representation --- or for an interpretation to not be defined at all. It is not acceptable for representations with an interpretation defined, to interpret the fragment identifier such that semantically inconsistent secondary representations are returned. Interpret them consistently, or don't interpret them, but don't do it inconsistently! So maybe an answer to Nathan's question needs qualification; IF for each representation of a resource an interpretation for a given fragment identifier has been defined, AND we assume that the server is exhibiting correct behavior, THEN we must accept that the secondary representations meet the providers definition of "consistent." Consistency is not the same as equivalence; two representations might return "consistent" secondary representations that cannot be considered "equal" because they are of entirely different content types. -- John S. Erickson, Ph.D. http://bitwacker.wordpress.com olyerickson@gmail.com Twitter: @olyerickson
Received on Friday, 12 March 2010 11:37:24 UTC