W3C home > Mailing lists > Public > public-tracking@w3.org > March 2012

Re: Initial feedback on the well-known URI Proposal

From: Rigo Wenning <rigo@w3.org>
Date: Wed, 07 Mar 2012 09:50:13 +0100
To: public-tracking@w3.org
Cc: "Roy T. Fielding" <fielding@gbiv.com>, Matthias Schunter <mts@zurich.ibm.com>
Message-ID: <2527372.6Oglm4Z05b@hegel.sophia.w3.org>
On Tuesday 06 March 2012 14:34:43 Roy T. Fielding wrote:
> > As a consequence, a site where each URL may have a different response
> > should live easier with headers; for retrieving the same info from a
> > well-known URI, the whole site needs to be 'mirrored' under the
> > well-known URI and the number of requests would double (Roy: Correct
> > me if I am wrong!).
> Actually, you are wrong, though for reasons that very few people would
> anticipate.  First, the 'mirror' is not of the site but of the resource
> namespace, and it ends at the first ancestor that has the same tracking
> policy as all of its descendants.  Descendants would redirect up.
> Second, there are no sites where every URL has its own tracking policy.
> Finally, in the worst case, the site can simply pick the union of all
> tracking behavior for the site and present that at the single
> /.well-known/dnt --- we do not penalize sites for saying they track more
> than they actually do for a given URI.


you're contradicting the entire P3P WG here:

I've set up the ref_files myself and failed for a site as complex as W3C's. 

While I can imagine that a simple site sets the response headers in a file to 
be downloaded, complex sites will have to define the scope if the response 
header and with the above you're only scratching the opening door to a complex 
can of worms. Defining is easy, implementing is very hard in this field: 

Definition: some regex will do:
  DNT reference files make statements about what DNT feedback value applies to 
a given URI. DNT reference files support a simple wildcard character to allow 
making statements about regions of URI-space. The character asterisk ('*') is 
used to represent a sequence of 0 or more of any character. No other special 
characters (such as those found in regular expressions) are supported.


In W3C datespace, files with different levels of access are sitting in the 
same folder. And different levels of access (logged-in) mean different 
tracking status. As a consequence, the file at the well-known location has to 
contain a list of all files under DNT policy. For W3C those are some 100k 
files or more. How heavy is that file at the well-known location now? How hard 
to generate?

BTW and with a reference to Aleecia's discussion with Shane about complex 
sites and headers: P3P contained the link-tag in the html page for that use 
case. We now would have RDFa to do that. 


Received on Wednesday, 7 March 2012 08:50:42 UTC

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