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RE: RFC 2396 revision issue: Query definition

From: Mark Nottingham <mnot@mnot.net>
Date: Thu, 21 Nov 2002 23:50:44 -0800
To: "'Mark Nottingham'" <mnot@mnot.net>, "'Graham Klyne'" <GK@ninebynine.org>
Cc: "'Hrvoje Simic'" <hrvoje.simic@zg.hinet.hr>, <uri@w3.org>
Message-ID: <000f01c291fb$de731ce0$370ba8c0@mnotlaptop>

> Not entirely; relative URIs treat path segments and query
> components very differently. This indirectly suggested to me 
> that there might be the concept of a "located resource" which 
> differs from the more discussed "identified resource". 
> Thinking about it more, I'm not at all sure that I'm not just 
> offering guidelines as well; the semantics are determined by 
> the server alone; it's just that some common conventions are 
> provided for making URIs more useful, especially when using 
> them to locate something.

After discussing this more offline, 

'Semantics' isn't the correct term to use; Graham pointed out that this
implies too much. His suggestion was 'processing model', and that seems
to capture it very well; When used as a locator, a URI has a processing
model that is used (usually to retrieve a representation of the
resource). Each URI scheme defines its own processing model that enables
location of resources of that type.

The question, then, is whether these (not resource-, site- or
non-location) processing models are exclusive to the agent that is doing
the location. If the query is considered as data to be consumed by the
resource, this means that the processing model is effectively
distributed; the resource consumes part of the URI as well (which indeed
seems to be the case today for most uses of query).

Remember that 'Resource' is an abstract concept; it does not have to
have a one to one mapping to code on the back end. Therefore, I see no
problem with saying that query is data to be consumed by the resource
during the process of location; if the resoruce happens to be spread
across several back-end facilities on the server, so be it.

To summarize, then, the idea is that:

* Query is part of the URI for the purposes of identification; every URI
with a different query string is a different identifier (just as it is
now).

* Query is data to be consumed by the resource during the process of
location (just as 2396 says).

* It is worthwhile to distinguish between URIs and URLs, not because
they identify different things, but because these terms can be used to
distinguish between different contexts of use - identification vs.
location.

E.g.,

Given:
  http://www.example.com/foo?bar
When used as an identifier (URI), the resource is
  http://www.example.com/foo?bar
While, in the context of a locator (URL), the resource located is
considered
  http://www.example.com/foo

I realise that this is a largely theoretical problem, in that it doesn't
affect how anything actually works; however, it may affect how people
think, which is just as, if not more, important.
Received on Friday, 22 November 2002 02:50:54 UTC

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