- From: Graham Klyne <GK-lists@ninebynine.org>
- Date: Sun, 26 Jun 2011 10:29:42 +0100
- To: Tim Berners-Lee <timbl@w3.org>
- CC: Xiaoshu Wang <xiao@renci.org>, Jonathan Rees <jar@creativecommons.org>, Alan Ruttenberg <alanruttenberg@gmail.com>, David Booth <david@dbooth.org>, Jeni Tennison <jeni@jenitennison.com>, "www-tag@w3.org List" <www-tag@w3.org>
Tim Berners-Lee wrote: > My software would assume that <http://www.knox.edu/Images/_News/news_media/img/2005/obama-barack-1ss.jpg> > was a document before doing any HTTP request, just as it assumes that <mailto:timbl@w3.org> is a mailbox > before sending any mail. However, others wanted to be able to use http: URIs like that for arbitrary things. > The TAG defined a compromise, so that you can only assume that it is a document if you get back 200. > I changed my code. I would have preferred otherwise, but I went along with the compromise > in order to get consensus and get interoperability. I think I understand and agree with the thrust of this, but the wording seems open to interpretation when you say "you can only assume that it is a document if you get back 200". I think that getting an HTTP 200 response is just *one* way that allows you to assume it is a document (if you trust the origin server). If one had (and trusted) an RDF document containing: <http://www.knox.edu/Images/_News/news_media/img/2005/obama-barack-1ss.jpg> a ex:Photo . (where ex:Photo denotes a class of things we know of as photographs, which are understood to be documents), then that is another way to justify this assertion. ... Thus, what I think we have here is that by performing an HTTP GET and receiving a 200 response allows us to infer: [ a ex:webService ; ex:runBy [ ex:withDomain "www.knox.edu" ] ] ex:claims { <http://www.knox.edu/Images/_News/news_media/img/2005/obama-barack-1ss.jpg> a ex:Photo } which under appropriate assumptions of trustworthiness may allow you to accept the inference: <http://www.knox.edu/Images/_News/news_media/img/2005/obama-barack-1ss.jpg> a ex:Photo . ... As far as I can tell, a 303 response doesn't of itself suggest any specific inferences, not even a negation of the above. I'm not up to speed on discussions of a 209 response, but I'm guessing the intent would be to license some different inferences. ... The bottom line, I think, is that the form of an HTTP URI (without fragment) tells us nothing about its denotation, but that we have network mechanisms to help us find out. #g -- Related, I think: [[ Constraint: Web software MUST NOT depend on the correctness of metadata inferred from a URI, except when the encoding of such metadata is documented by applicable standards and specifications. ]] -- http://www.w3.org/2001/tag/doc/metaDataInURI-31
Received on Sunday, 26 June 2011 14:24:56 UTC