W3C home > Mailing lists > Public > public-lod@w3.org > November 2009

Re: RDF Update Feeds + URI time travel on HTTP-level

From: Erik Hetzner <erik.hetzner@ucop.edu>
Date: Mon, 23 Nov 2009 15:59:50 -0800
To: Linked Data community <public-lod@w3.org>
Message-ID: <P-IRC-EXBE01QkdzgXO0000294d@EX.UCOP.EDU>
At Mon, 23 Nov 2009 00:40:33 -0500,
Mark Baker wrote:
> 
> On Sun, Nov 22, 2009 at 11:59 PM, Peter Ansell <ansell.peter@gmail.com> wrote:
> > It should be up to resource creators to determine when the nature of a
> > resource changes across time. A web architecture that requires every
> > single edit to have a different identifier is a large hassle and
> > likely won't catch on if people find that they can work fine with a
> > system that evolves constantly using semi-constant identifiers, rather
> > than through a series of mandatory time based checkpoints.
> 
> You seem to have read more into my argument than was there, and
> created a strawman; I agree with the above.
> 
> My claim is simply that all HTTP requests, no matter the headers, are
> requests upon the current state of the resource identified by the
> Request-URI, and therefore, a request for a representation of the
> state of "Resource X at time T" needs to be directed at the URI for
> "Resource X at time T", not "Resource X".

I think this is a very compelling argument.

On the other hand, there is, nothing I can see that prevents one URI
from representing another URI as it changes through time. This is
already the case with, e.g.,
<http://web.archive.org/web/*/http://example.org>, which represents
the URI <http://example.org> at all times. So this URI could, perhaps,
be a target for X-Accept-Datetime headers.

There is something else that I find problematic about the Memento
proposal. Archival versions of a web page are too important to hide
inside HTTP headers.

To take the canonical example, if I am viewing
<http://oakland.example.org/weather>, I don’t want the fact that I am
viewing historical weather information to be hidden in the request
headers.

Furthermore, I am viewing resource X as it appeared at time T1, I
should *not* be able to copy that URI and send it to a friend, or use
it as a reference in a document, only to have them see the URI as it
appears at time T2.

I think that those of us in the web archiving community [1] would very
much appreciate a serious look by the web architecture community into
the problem of web archiving. The problem of representing and
resolving the tuple <URI, time> is a question which has not yet been
adequately dealt with.

best,
Erik Hetzner

1. Those unfamiliar with web archives are encouraged to visit
<http://web.archive.org/>, <http://www.archive-it.org/>,
<http://www.vefsafn.is/>, <http://webarchives.cdlib.org/>, ...

;; Erik Hetzner, California Digital Library
;; gnupg key id: 1024D/01DB07E3

Received on Tuesday, 24 November 2009 00:00:00 UTC

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