add Warning header field examples

[julian.reschke@…]

Quoting <​http://www.w3.org/mid/413C419A-AE9D-46F8-82A5-72B4341754AD@gbiv.com>:

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"

(...)

[julian.reschke@…]

proposed examples section

[fielding@…]

Thanks, but those examples are more extensive than needed. A warn-date serves no purpose on a 214.

I already made the section headers look like valid examples (without warn-date); I will add one example with a warn-date.

[fielding@…]

From [2409]:

add example Warning and recommend - be used as pseudonym when name is unknown; addresses #496

[julian.reschke@…]

From [2412]:

Note change for [2409] (see #496)