ISSUE-120: Should the response header be mandatory (MUST) or recommended (SHOULD)

Should the response header be mandatory (MUST) or recommended (SHOULD)

State:
CLOSED
Product:
Tracking Preference Expression (DNT)
Raised by:
Matthias Schunter
Opened on:
2012-01-30
Description:
We had discussions whether the response header should be mandatory (MUST; A site not sending a header is deemed non-compliant) or recommended (SHOULD; user agent cannot derive compliance but will usually assume non-compliance if header is missing).
Related Actions Items:
Related emails:
  1. Re: Agenda for July 18, 2012 DNT WG Call on TPE (from fielding@gbiv.com on 2012-07-18)
  2. Issues mentioned in the TPE document, or non-closed in the database and applying to TPE (from singer@apple.com on 2012-04-10)
  3. Tracking Status Hybrid (from tom@mozilla.com on 2012-04-05)
  4. Re: Issue Maintenance (from jmayer@stanford.edu on 2012-03-29)
  5. Re: Issue Maintenance (from fielding@gbiv.com on 2012-03-28)
  6. Issue Maintenance (from mts-std@schunter.org on 2012-03-28)
  7. Re: Issue-107, Issue-120, Issue-124 (from fielding@gbiv.com on 2012-02-27)
  8. Re: Issue-107, Issue-120, Issue-124 (from npdoty@w3.org on 2012-02-27)
  9. Re: Issue-107, Issue-120, Issue-124 (from fielding@gbiv.com on 2012-02-27)
  10. Re: Issue-107, Issue-120, Issue-124 (from john@consumerwatchdog.org on 2012-02-27)
  11. Re: Issue-107, Issue-120, Issue-124 (from singer@apple.com on 2012-02-27)
  12. Issue-107, Issue-120, Issue-124 (from john@consumerwatchdog.org on 2012-02-27)
  13. Agenda for 2012-Feb-22 call (from mts@zurich.ibm.com on 2012-02-21)
  14. Re: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from singer@apple.com on 2012-02-07)
  15. Re: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from gelman@blurryedge.com on 2012-02-06)
  16. Re: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from gelman@blurryedge.com on 2012-02-06)
  17. RE: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from wileys@yahoo-inc.com on 2012-02-06)
  18. RE: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from wileys@yahoo-inc.com on 2012-02-06)
  19. RE: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from wileys@yahoo-inc.com on 2012-01-31)
  20. Re: Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from singer@apple.com on 2012-01-31)
  21. Agenda for 2012-02-01 call (V02: added more incoming issues with text) (from mts@zurich.ibm.com on 2012-01-31)
  22. Re: tracking-ISSUE-120: Should the response header be mandatory (MUST) or recommended (SHOULD) [Tracking Preference Expression (DNT)] (from mts@zurich.ibm.com on 2012-01-31)
  23. RE: tracking-ISSUE-120: Should the response header be mandatory (MUST) or recommended (SHOULD) [Tracking Preference Expression (DNT)] (from wileys@yahoo-inc.com on 2012-01-30)
  24. tracking-ISSUE-120: Should the response header be mandatory (MUST) or recommended (SHOULD) [Tracking Preference Expression (DNT)] (from sysbot+tracker@w3.org on 2012-01-30)

Related notes:

MUST
+User agent can reliably determine standards compliance claims
- All existing sites are rendered non-compliant (even if they do not track)

SHOULD
+ Less implementation effort
+ Allows a server a 3rd state 'don't know' similar to user preference
+ Legacy servers that do not track are compliant (even though nobody notices)

Matthias Schunter, 30 Jan 2012, 20:30:09

2012-01-19 Proposed Text (A): A site that receives DNT;1 MUST follow the corresponding practices as defined in the [standards compliance] document and SHOULD send a corresponding DNT response header.

Note: If a site chooses not to send a response header, then the user agent does not obtain information whether the preference has been accepted or not. This may have negative consequences for the site such as:
- Preventive measures by user agents
- Being flagged as non-compliant by scanning tools that look for response headers

Matthias Schunter, 31 Jan 2012, 13:08:29

Status change: OPEN [Waiting for Tom/Roy input; currently no final text on the table]

Matthias Schunter, 4 Apr 2012, 09:18:52

Completed in r1.112.

Roy Fielding, 29 Apr 2012, 11:15:52

Well-known URI is mandatory. Header only to inducate that the site-wide URI has changed and that the user agent should re-retrieve the well-known URI.

Matthias Schunter, 21 Jun 2012, 23:30:32

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