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Re: URI for abstract concepts (domain, host, origin, site, etc.)

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 26 Jun 2009 10:46:47 -0500
Cc: Dan Connolly <connolly@w3.org>, "apps-discuss@ietf.org" <apps-discuss@ietf.org>, "www-tag@w3.org" <www-tag@w3.org>, URI <uri@w3.org>
Message-Id: <66FB7DD9-7D0B-4877-ACBE-1618507CBFDA@ihmc.us>
To: Eran Hammer-Lahav <eran@hueniverse.com>

On Jun 25, 2009, at 10:18 PM, Eran Hammer-Lahav wrote:

>> From: Dan Connolly [mailto:connolly@w3.org]
>> Sent: Thursday, June 25, 2009 7:52 PM
>>> How would a client know that this URI isn't for an actual HTTP
>> resource without creating "well-known-location" URIs (option #1 in my
>> original email)?
>> It _is_ for an actual HTTP resource; i.e. something
>> described/discussed in a document you can get by HTTP. Since
>> documents can describe/discuss anything, they can describe/discuss
>> things like origins and such. RDF is particularly suited
>> for this purpose, but I can imagine other media types
>> might work too... text/html with RDFa is pretty hip
>> these days.
> In my case, the "resource" is the concept of a host, which is the  
> combination of a domain name, port number, and protocol used on that  
> port. I want to be able to describe this host by saying, "this is  
> how you transform any HTTP URI that belongs to this host to the URI  
> of its metadata". There are plenty of ways to express this statement  
> but so far I don't have a good way to express the subject of this  
> statement - the host.

To me this sounds like a clear use case for an RDF blank node. You  
want to refer to some (category of) thing that has no current naming  
convention, but which you can describe in terms of its properties.  
That is exactly what RDF bnodes were invented for. The relevant RDF  
graph fragment would look something like this, using triples notation  
for clarity:

_:x rdf:type :HostClassName .
_"x :hasDomainName <nameasastringliteral>^^xsd:string .
_:x :hasPortNumber <portnumber>^^xsd:number .  (Or maybe you want to  
keep it as a string)
_:x :usesProtocol  .... (Not sure how to express this, you might have  
to  use a literal to encode the protocol name or some such, unless  
there is an ontology of protocols out there somewhere.)

to which you then add whatever you want to say about it, with that  
same _:x as subject.

If you (as many people do) dislike bnodes, than just invent a naming  
convention with URI references #ed onto a suitable URI you own: the  
use of # gives you freedom to use your own naming style, and bypasses  
the http-range-14 referential problems arising from the use of a bare  

Pat Hayes

> Of course, I can come up with something like this:
> http://abstract.example.net/host/example.com:80:http
> And simply include in the protocol that the http://abstract.example.net/host/ 
>  prefix is a special case exception. But while such solutions (a URI  
> version of a well-known location) might be acceptable for HTTP  
> servers due to the complexity and cost of deploying changes to the  
> infrastructure (such as a new HTTP method), they are less acceptable  
> for URIs which can be easily extended with nothing more than a  
> couple pages of spec...
> It is almost as easy to register a new URI scheme or URN namespace  
> as it is for me to buy and maintain a new domain name. But I think  
> in this case, the reserved domain name is a lot more offensive to  
> web architecture than a new URI scheme or some other URI-based  
> solution.
> I am also happy to make this as specific as needed for my super  
> special use case and mint a new host: URI scheme.

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Received on Friday, 26 June 2009 15:47:29 UTC

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