p6: Warning header field

"Roy T. Fielding" <fielding@gbiv.com> Sun, 09 June 2013 07:25 UTC

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From: "Roy T. Fielding" <fielding@gbiv.com>
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Subject: p6: Warning header field
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I just noticed that the definition of the Warning header field
includes a required host or pseudonym between the warn-code and
the warn-text, and further that the warn-text is a quoted-string.

Since there are no examples provided, and the table of warn-codes
makes them look like status-code reason-phrase, it should be no
surprise that implementations send things like

  Warning: 110 Response is stale
  Warning: 110 squid/3.2.0.5 "Response is stale"
  Warning: 111 squid/3.2.0.5 "Revalidation failed"
  Warning: 111 Revalidation failed
  Warning: 112 Disconnected Operation
  Warning: 214 host.example.com Transformation applied

In fact, the only places I can find correctly formatted Warning
header fields is in an internal Apache debugging module (mod_policy,
abusing that field for other means) and within a BEA example for SIP.

  Warning: 307 isi.edu "Session parameter 'foo' not understood"

I haven't found any that send the optional warn-date.

Obviously, examples are needed in p6, unless I can delete the
header field and be done with it.

....Roy