- From: Manu Sporny <msporny@digitalbazaar.com>
- Date: Thu, 19 Mar 2009 02:52:48 -0400
- To: Peter Mika <pmika@yahoo-inc.com>
- CC: RDFa <public-rdf-in-xhtml-tf@w3.org>, "public-rdfa@w3.org" <public-rdfa@w3.org>
Peter Mika wrote: > I would like to start by saying that we are always open for dialog! That is very good to hear and I do appreciate you following up on this thread. :) > I would like to add --simply because it seems to be a common > misunderstanding-- is that you can use any and all vocabularies in > conjunction with SearchMonkey, including your own media vocabularies. Thanks for the clarification, although my point was in reference to this page: http://developer.search.yahoo.com/help/objects/video SearchMonkey outlines what people must do to get their video listings in Yahoo's search service using the Yahoo Media vocabulary. So while you can write your own SearchMonkey apps using your own vocabularies, you can (right now) only use Yahoo's vocabulary if you want the enhanced search listings to show up on the main Yahoo search page, right? This sends a pretty strong message - use Yahoo's vocabularies or you won't show up in the enhanced listings. What's the timeline for allowing other vocabularies to be used for indexing purposes for the main search page listings? > As a way of explanation, you also have to know that when creating the > initial SearchMonkey documentation, we included vocabularies that we > felt were stable enough, covered major interests, and were widespread > including Dublin Core, FOAF and others. This was a very good move, and I commend your team for not re-inventing the wheel and for re-using pre-existing vocabularies. > However, we wanted the > documentation to be complete and provide simple vocabularies in areas > where none existed or on the contrary, too many existed. The engineer > who created the media vocabulary followed the best practice of taking an > existing format (MediaRSS) and translating it into RDF. The MediaRSS syndication format does not map cleanly into a rich RDF vocabulary. Even if it did, the vocabulary should have been called Media RSS RDF, or used the "mrss:" prefix to be more clear about what is going on. Taking something that already exists for syndication purposes and transforming it into an RDF vocabulary on a 1-to-1 basis is not a best practice because the syndication format makes some very strong assumptions about the data in the stream. RSS data is fairly strongly typed data, and is machine generated in a controlled environment. RDFa data is usually not strongly typed, is generated by humans as well as machines, and is not in a very controlled environment. MediaRSS also contains both elements /and/ attributes to refine the meaning of the elements. However, it seems that only the elements made it over to ymedia, which is unfortunate because a great deal of semantic fidelity is lost without the attributes. Also, the vocabulary specifies both ymedia:title /and/ suggests the use of dc:title. There is no need for ymedia:title since you're just re-defining what dc:title already does. There is an argument for helping web authors by only requiring them to include one vocabulary, but it is at the expense of teaching people that it's okay to re-create entire vocabularies under that argument - which is detrimental to all of this in the long run. I think the solution would be something along the lines of @profile pre-loading a set of vocabularies, so Yahoo could use multiple vocabularies in a stack without creating undue burden on the HTML author: <html profile="http://search.yahoo.com/searchmonkey-vocabs.html"> ... <span property="dc:title">Puppies</span> ... ... <span property="format:width" content="1080">HD</span> .. > We do publish OWL definitions for the vocabularies at [2]. Good! But that's so 2007! :) Why not mark up the same pages that define the human readable vocabulary with a machine readable one using RDFa, like these pages do: http://purl.org/media/ http://purl.org/media/audio http://purl.org/media/video http://purl.org/commerce/ > All your suggestions to improve this > vocabulary or any other are highly welcome. There are only two > requirements: they have to be specific enough to implement and backwards > compatible. Fair enough. > (As we are painfully aware of, schema versioning is an > unsolved problem on the Semantic Web.) Hmm, maybe... I thought the general sense on the web was that schema versioning was a bad idea and should not be done. If you really need to shift versions, you can always point people at a new URL and clearly mark the old URL as deprecated, as the Dublin Core folks did. > The only non-issue I see from > your list of comments is the issue of prefixes: we have URIs in RDF(a) > and there already plenty of namespace clashes in the sense you describe: > RDF Calendar and Dublin Core both have at least two namespaces. Right, which is why I pointed out RDFa's resiliency in the previous e-mail... but it still does create a rather large problem for these types of proposals, so I don't think it is a non-issue... just one that we may be able to begrudgingly live with: http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2009Mar/0037.html Hope to keep working through the issues and providing feedback. Thanks for replying and reading through this rather long set of thoughts :) -- manu -- Manu Sporny President/CEO - Digital Bazaar, Inc. blog: Absorbing Costs Considered Harmful http://blog.digitalbazaar.com/2009/02/27/absorbing-costs-harmful
Received on Thursday, 19 March 2009 06:53:27 UTC