RE: Headers modified along the way against user (non) choices

What would be the objective of echoing the request?  What would we expect the browser to do with the information?  They could warn the user, but in most cases, I doubt the user cares why their DNT preference is being ignored and I would expect both the user and the browser to react exactly the same as if the server simply returned a DNT:0.  At best, the browser could provide the additional information "the site may not be at fault so you may want to try this site on a different network".  This does not seem worth the extra complexity.

The other purpose I can see of echoing the request is trying to determine which proxies or other services were altering the header.  I personally would hate to bloat the specification for debugging purposes.  There has to be a more elegant method for doing this since every new header has experienced the same problem and I am not familiar with any others requiring an echo.

What other benefits could be derived from echoing the request?

-----Original Message-----
From: Karl Dubost [mailto:karld@opera.com] 
Sent: Wednesday, November 09, 2011 11:25 AM
To: public-tracking@w3.org Group WG
Subject: Headers modified along the way against user (non) choices

On the call today, we discussed about user choice on setting the DNT header.
(Thinking out loud, not a strong opinion)

Basically the header sets 

	DNT: 1 

and along the way a proxy modified the header for

	DNT: 0 

the final server knows only the last value and then might not be able to behave according to user choices.

* CGI
  Roy proposed on IRC to have a cgi script on the final server 
  displaying what headers it has received. Issues because it 
  means the user has to understand what is happening. 

* Echo
  another possibility would be having the server sending back 
  in the response a header with the original DNT header. 
  Server sending something like (not the formal syntax)
  DNT-received: 0
  This has issues too. Ian Fette will say too heavy?
  And a proxy can still modify it on the way back too.





-- 
Karl Dubost - http://dev.opera.com/
Developer Relations & Tools, Opera Software

Received on Friday, 11 November 2011 19:49:07 UTC