W3C home > Mailing lists > Public > public-tracking@w3.org > October 2011

Re: Well-known URI vs response headers? [ISSUE-81, ISSUE-47, ISSUE-80]

From: Rigo Wenning <rigo@w3.org>
Date: Fri, 28 Oct 2011 13:24:06 +0200
To: public-tracking@w3.org
Cc: Matthias Schunter <mts@zurich.ibm.com>
Message-ID: <5994742.Sq3xYxlDfj@longtarin>
Hi Matthias, 

if all the site honors DNT or P3P, no issue. We have a well-known location in 
P3P and we had to steam-roll Dan Connolly to get it. All is now very simple: 
The browser checks the well-known location, finds the policy (or DNT 
confirmation) and done for the entire site. Simple! Do you check that with 
every http-request? It may change. What does that mean for the policy 
assertion being made?

Now imagine that some parts of a site are DNT enabled, others are not. In your 
well-known location (wkl), you will have to tell the DNT client which part of 
the site can do DNT and which can't. The client will have to remember, so it 
can avoid to request the DNT  wkl with every request. We will invent regex in 
the file on the wkl to determine the parts of the site that can do DNT and 
those they don't. And we will invent caching as sites are more complex than we 
imagined because the file became bigger and bigger.

Now imagine you're akamai or some other cloud thingy. The request of the 
content goes to your site (e.g. large images) because your globally 
distributed system is designed to improve loading times. The way this works is 
that you request the image from xyz.akamai.net. So every akamai server has to 
know about all clients it provides content for and whether they can do DNT or 
not. If you put all this information in a wkl, the file will be huge. But it 
is no issue to have a server-side smallish simple database that determines 
when to send DNT=1 (enabled) or not.

Now imagine, you're a technology provider who provides content for customers 
from own servers that are dynamically meshed into your customer's content. How 
would you construct a wkl here?

Creativity of configurations of http servers is endless. The wkl can't cope 
with that. I'm just saying that I got my fingers already burned once. 

Best, 

Rigo

On Thursday 27 October 2011 09:32:19 Matthias Schunter wrote:
> Roy (the editor & http guru) and I perceive a well-known URI to be the
> simpler option: Once a user has turned on DNT, a simple round-trip to
> check this URL to us seemed simpler than adding a response header to
> all (many!)  http responses.
Received on Friday, 28 October 2011 11:24:23 UTC

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