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meeting record: 2009-07-09 RDFa Task Force

From: Ralph R. Swick <swick@w3.org>
Date: Thu, 16 Jul 2009 11:17:45 -0400
Message-Id: <>
To: public-rdf-in-xhtml-tf@w3.org
Cc: public-swd-wg@w3.org
The record of *last week's* RDF-in-XHTML Task Force telecon
are now updated with the clean copy:


The delay in publishing this cleaned version is entirely mine;
Manu sent them to me the day of the meeting.  Thanks, Manu.

A text snapshot follows.


                       RDFa in XHTML Task Force

09 Jul 2009


      [2] http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2009Jul/0032.html

   See also: [3]IRC log, previous:

      [3] http://www.w3.org/2009/07/09-rdfa-irc
      [4] http://www.w3.org/2009/06/25-rdfa-minutes.html


          Manu Sporny, Steven Pemberton, Shane McCarron, Mark Birbeck,
          Ralph Swick

          Ben Adida, Michael Hausenblas

          Manu Sporny



     * Topics
         1. Use of regular CURIEs in @rel
         2. Processing of xmlns:* in non-XML languages
         3. Case sensitivity in xmlns:
     * Summary of Action Items

   <scribe> ACTION: Ben to author wiki page with charter template for
   RDFa IG. Manu to provide support where needed. [recorded in

     [10] http://www.w3.org/2009/05/28-rdfa-minutes.html#action10

   <scribe> ACTION: Ben to prepare "how to write RDFa" screencast with
   fragment parser [recorded in

     [11] http://www.w3.org/2009/06/11-rdfa-minutes.html#action05

   <scribe> ACTION: Mark create base wizard suitable for cloning
   [recorded in

     [12] http://www.w3.org/2008/09/11-rdfa-minutes.html#action12

   <scribe> ACTION: Mark to send Ben ubiquity related wizard stuff
   [recorded in

     [13] http://www.w3.org/2008/11/20-rdfa-minutes.html#action11

   <scribe> ACTION: Mark write foaf examples for wiki [recorded in

     [14] http://www.w3.org/2008/09/11-rdfa-minutes.html#action13

   <scribe> ACTION: Ralph find the statement on test suite copyright
   [recorded in
   [15]http://www.w3.org/2009/06/04-rdfa-minutes.html#action13] [DONE]

     [15] http://www.w3.org/2009/06/04-rdfa-minutes.html#action13

   <scribe> ACTION: Ralph make a request for an RDFa issue tracker
   instance [recorded in

     [16] http://www.w3.org/2009/05/28-rdfa-minutes.html#action11

   <scribe> ACTION: Ralph or Steven fix the .htaccess for the XHTML
   namespace [recorded in
   9/01/08-rdfa-minutes.html#action01] [CONTINUES]

     [17] http://www.w3.org/2009/01/08-rdfa-minutes.html#action01

   <scribe> ACTION: Ralph think about RSS+RDFa [recorded in
   1-rdfa-minutes.html#action15] [CONTINUES]

     [18] http://www.w3.org/2008/09/11-rdfa-minutes.html#action15

   Manu: Any changes to agenda?

   <Steven> Agenda:

     [19] http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2009Jul/0032

   markbirbeck: I'm concerned about safe CURIEs in @rel
   ... Could we move #4 up to the first item?
   ... It might help to address major objections - it's been hanging on
   for some time.
   ... Simple solution is to do safe CURIEs in @rel.

   Manu: Moving agenda item 4 up to 1

Use of regular CURIEs in @rel

   ShaneM: I don't think we can do safe CURIEs in @rel

   markbirbeck: I think this is a broader problem
   ... I think the whole issue is @rel="URL" is happening in Atom and
   other standards.
   ... We should recognize that this is a broader thing that people
   take issue with.
   ... We should come up with a major clarification, or we should try
   to come up with a solution.
   ... Just trying to set the context for this discussion.

   ShaneM: I agree that that is the context.
   ... I think it's good that people are using 'relations' with URIs.
   ... I don't think that Atom has anything to do with HTML.
   ... different protocol, different markup language.
   ... If we were to change the syntax of @rel now, it would break
   every page that is using RDFa already.
   ... It is an incompatible, dramatic, drastic change.

   Steven: I think you're right - it was a decision we made long ago.
   ... I don't think it's a good idea.

   markbirbeck: The argument when we made the decision was what happens
   when we use legacy values.
   ... It didn't occur to us at the time that it didn't preclude using
   safe CURIEs.

   markbirbeck: So we could've done it, but we didn't do it. It's a
   shame, really.
   ... There is another use case - the only way to get a URL into @rel
   is to use a CURIE.
   ... It's the xmlns:http hack...
   ... It's a bit of a pain for some scenarios.
   ... I can see why people don't like it - it requires prefix mappings
   to be there.

   Steven: Since you have URLs in some places and CURIEs in some places
   ... A typical syntax for that is to use <> when you use a URI.
   ... This wouldn't work now, ofcourse.

   markbirbeck: The ideal scenario would be that every attribute could
   carry a CURIE, URI or token.
   ... The use of XML namespaces in RDF makes the assumption that you
   have this concept of a prefix... it's baggage.

   <Steven> well, it would be difficult in XML/HTML, since < and > have
   special meaning

   <Steven> {[20]http://www.w3.org}

     [20] http://www.w3.org/

   markbirbeck: Maybe we should explore Shane's point about it breaking

   ShaneM: Look at Google's implementation = v:foo

   <Steven> ?[21]http://www.w3.org?

     [21] http://www.w3.org/

   markbirbeck: One way to do it would be to signal a switch - to
   specify which version of RDFa you are using.

   <Steven> |[22]http://www.w3.org|

     [22] http://www.w3.org/

   ShaneM: We didn't require any sort of announcement mechanism.
   ... @profile and @version come to mind.

   markbirbeck: There is nothing to stop defining RDFa in X as
   different in RDFa in Y.

   Steven: It would be nice if we had a unified syntax.
   ... Can't we find a good way of marking a URI when a CURIE is

   Ralph: If there are reasons for RDFa to be different because of host
   language matters, that's one thing.
   ... I don't have to want to know that there are different versions
   of RDFa.

   markbirbeck: The google example will have a defined namespace.
   ... That namespace will be defined.

   Steven: Every CURIE or token begins with a letter.
   ... We just have to choose a non-letter.

   ShaneM: I disagree.
   ... It's as simple as saying that if a namespace is not defined,
   then it is a URI.

   markbirbeck: Yes.
   ... We probably discussed this ages ago - but not that it is so
   pressing, we should revisit this.
   ... Do we get any false positives?
   ... Do you falsely get a URL when somebody forgot to add the
   namespace? Yes... but tough.
   ... We should also allow square brackets.

   ShaneM: What happens when somebody re-defines "urn:"?

   Manu: Tough - they made a concious decision to do so.

   markbirbeck: I agree.
   ... @rel="URL" is a handy thing.
   ... It addresses the cut/paste problem.
   ... If you're generating a snippet, you might as well just use URLs.
   ... I think what happened with square brackets was that we did
   rel="[next]" and people didn't like that.
   ... We never went down the road of only use rel="[prefix:suffix]"
   ... "if the prefix is undefined, it's a URI" would work everywhere.

   ShaneM: The TAG has made it very clear that the issue with CURIEs is
   that they look like URIs.
   ... Now we're going down a road that may upset the TAG - all of a
   sudden it's difficult to differentiate between CURIEs and URIs.

   Steven: We had no choice - we didn't invent this.
   ... we extended an existing notation.
   ... It looks just like QNames.

   ShaneM: The TAG has a dislike for QNames in attributes.

   Ralph: That's correct, that practice was not encouraged in attribute

   markbirbeck: The presence of a namespace prefix mapping makes it
   clear what you mean.
   ... You can diferentiate them when the statement is in context.

   Manu: Do we want to pass this approach by the list?

   ShaneM: It doesn't even change the RDFa in XHTML spec.

   markbirbeck: It's backwards compatible.

   ShaneM: The RDFa in XHTML spec would have to change a bit.

   markbirbeck: We may want to write an RDFa in HTML spec, that states
   this new rule.

   Manu: Mark, can you write a proposal and send it to the RDFa mailing

Processing of xmlns:* in non-XML languages

   Manu: Mark can you start by talking about the @token proposal?

   markbirbeck: Yes - the @token is about bridging to the simplicity of
   ... We may want to also help people create tokens on the fly to
   represent full URIs in a Microformats-style way.
   ... This @token spec would allow authors to define tokens,
   regardless of the host language.
   ... Instead of doing @prefix - you'd use @token.
   ... You could use 'dc' on it's own, without having to use a
   reference or suffix.
   ... The criticism is "How do you follow your nose?"
   ... Do you really need to make a request to find out what the tokens
   are? Via @profile?
   ... One answer is that for many of the standard use cases, you
   wouldn't have to go off to make the retrieval.
   ... Ben's criticism wonders whether the mapping should be done at
   another level.
   ... He's not here to make that case, so we may not be able to get
   much further on this.

   Manu: Shane, elaborate on criticism of @token proposal.

   ShaneM: Not concerned about multiple requests.
   ... We make MANY connections when loading a web page
   ... We also cache stuff - so it's not an issue... it's how it should
   ... Manu and I put together a proposal that is similar to this
   called RDFa Profiles.
   ... We started this discussion thinkinking that it is just a mental
   model - now we know that it's not.
   ... The problem we're trying to solve is to see if there is a way
   for authors to extend the list of reserved words.
   ... The proposal that Manu and I had was that the proposal needed an
   external document.
   ... The external document was turned for RDF automatically.
   ... My criticism of the @token proposal is that it's not clear how
   we get from embedded declaration to the RDF declaration. How do you
   follow your nose with @token?
   ... I think that's Ben's concern as well.

   markbirbeck: Just to understand... do you mean "What would the
   external document look like?"
   ... Or how to you get from @token to RDF?
   ... All I'm proposing is a small change to the CURIE spec.

   ShaneM: Yes, I get that.

   markbirbeck: So the minor change is that we can expand prefixes for
   CURIEs and stop there.
   ... The external document should itself be HTML+RDFa... as long as
   it maps to a set of triples.
   ... Somehow we get a list of mappings from that external document.
   ... The first approach is we just have @token and that's how the
   mapping is created.
   ... Not saying anything about the syntax in the @token attribute.
   ... Just saying that if one of the prefixes match in a CURIE via a
   @token, it should be used.

   ShaneM: If what we're talking about is having dynamically extensible
   reserved words... we should divorce the conversation from new
   ... If that is a fine thing to do, then so be it.
   ... We should make sure that the endpoint should be HTML+RDFa.
   ... The thing that is referenced should be an HTML+RDFa document.

   Ralph: The whole semantic web stack should be dereference-able in
   some RDF form.

   ShaneM: In the case of Microformats, we talked about how to extend
   the XMDP format that they use with RDFa to give something that looks
   almost exactly like Microformats.

   <markbirbeck> We already support this:

   <markbirbeck> @xmlns:author="[23]http://example.org/author"

     [23] http://example.org/author

   <markbirbeck> @rel="author:"

   markbirbeck: I think we should move away from using prefix:suffix to
   something that could expand without the colon.
   ... so why not this: xmlns:author="[24]http://example.org/author"
   and then rel="author"
   ... It makes it very easy to do cut/paste snippets.
   ... This is the "let's make it easier" approach.
   ... So, how do we define these things?
   ... We all agree that we need to create @prefix, so why not @token.
   ... If we are going to add a new attribute, why not add this feature
   as well?

     [24] http://example.org/author

   ShaneM: This is a fine approach.
   ... Ben's position is to say that xmlns: works, so we don't need to
   change anything.

   Ralph: There will be a discussion on distributed extensibility in
   HTML and that will probably include a discussion on xmlns:*

   <markbirbeck> "RDFa means extensibility (which is why some people
   will never support it)":

     [25] http://webbackplane.com/mark-birbeck/blog/2009/01/rdfa-means-extensibility

   Ralph: xmlns:* isn't necessarily dead, but I'm ok with referring to
   it by a different name to aid the discussion.

   ShaneM: So, we could write a new CURIE spec since there isn't a
   current CURIE spec.
   ... if we change anything like this, we're going to have to rev the
   ... If we are going to rev the spec, it would be a good change.

   markbirbeck: If we add @prefix, why not call it @token - that's
   where I was coming from.

   <ShaneM> there should be incremental improvement of RDFa by updating
   the spec.

   markbirbeck: People still have to decide whether to use RDFa or
   ... We should consider that (making RDFa easier to use) when revving
   the spec.

Case sensitivity in xmlns:

   <ShaneM> errata is here

     [26] http://www.w3.org/MarkUp/2008/REC-rdfa-syntax-20081014-errata/

   Manu: Document authors should use lower-case xmlns:prefix-names to
   be compatible across all processors.
   Steven: +1

   markbirbeck: Is it not possible to rev the spec and include HTML?

   ShaneM: No, absolutely not.
   ... not chartered to do so.

   Ralph: That is correct.


     [27] http://www.semanticuniverse.com/premium/audio/semtech-2009-audio-semantics-google-rfda-microformats-and-more.html

   <markbirbeck> That's the SemTech talk from Google, for those who
   couldn't be there.

Summary of Action Items

   [DONE] ACTION: Ralph find the statement on test suite copyright
   [recorded in
   [PENDING] ACTION: Ralph or Steven fix the .htaccess for the XHTML
   namespace [recorded in
   [PENDING] ACTION: Ben to author wiki page with charter template for
   RDFa IG. Manu to provide support where needed. [recorded in
   [PENDING] ACTION: Ben to prepare "how to write RDFa" screencast with
   fragment parser [recorded in
   [PENDING] ACTION: Mark create base wizard suitable for cloning
   [recorded in
   [PENDING] ACTION: Mark to send Ben ubiquity related wizard stuff
   [recorded in
   [PENDING] ACTION: Mark write foaf examples for wiki [recorded in
   [PENDING] ACTION: Ralph make a request for an RDFa issue tracker
   instance [recorded in
   [PENDING] ACTION: Ralph think about RSS+RDFa [recorded in

     [28] http://www.w3.org/2009/06/04-rdfa-minutes.html#action13
     [29] http://www.w3.org/2009/01/08-rdfa-minutes.html#action01
     [30] http://www.w3.org/2009/05/28-rdfa-minutes.html#action10
     [31] http://www.w3.org/2009/06/11-rdfa-minutes.html#action05
     [32] http://www.w3.org/2008/09/11-rdfa-minutes.html#action12
     [33] http://www.w3.org/2008/11/20-rdfa-minutes.html#action11
     [34] http://www.w3.org/2008/09/11-rdfa-minutes.html#action13
     [35] http://www.w3.org/2009/05/28-rdfa-minutes.html#action11
     [36] http://www.w3.org/2008/09/11-rdfa-minutes.html#action15

   [End of minutes]

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