13/09/13 09:50:28 (8 years ago)

Revert [2368] that attempted to address #486 because it adds incompatible requirements to HTTP/1.1 senders of Warning

1 edited


  • draft-ietf-httpbis/latest/p6-cache.xml

    r2372 r2382  
    17551755  <x:ref>warning-value</x:ref> = <x:ref>warn-code</x:ref> <x:ref>SP</x:ref> <x:ref>warn-agent</x:ref> <x:ref>SP</x:ref> <x:ref>warn-text</x:ref>
    1756                                           <x:ref>SP</x:ref> <x:ref>warn-date</x:ref>
     1756                                        [<x:ref>SP</x:ref> <x:ref>warn-date</x:ref>]
    17581758  <x:ref>warn-code</x:ref>  = 3<x:ref>DIGIT</x:ref>
    1795    HTTP/1.0 caches will cache all Warnings in responses, without deleting the
    1796    ones in the first category. Thus, Warnings in responses carry a warning-date
    1797    field, which can help in detecting an erroneously cached Warning.
    1798 </t>
    1799 <t>
    1800    RFC 2616 made the Warning header field's warn-date component optional; it
    1801    was only required to be sent when the recipient's version was HTTP/1.0 or lower.
    1802    However, deployment experience has shown that many intermediaries
    1803    do not process the Warning header field as required by RFC 2616. This results in
    1804    situations where the field can appear in messages where it is not applicable, because
    1805    a warning-value has not been removed by an intermediary.
    1806 </t>
    1807 <t>
    1808    As a result, this specification shifts responsibility for processing of Warning from
    1809    intermediaries to the recipient that is actually consuming them.
    1810 </t>
    1811 <t>
    1812    Generators of Warning header fields &MUST; include in every warning-value
    1813    a warn-date that matches the <x:ref>Date</x:ref> header field in the message. Recipients that
    1814    process a Warning header field &MUST; ignore (and &MAY; remove before forwarding)
    1815    a warning-value whose warn-date is different from the Date value in the response.
     1795   If an implementation sends a message with one or more Warning header fields
     1796   to a receiver whose version is HTTP/1.0 or lower, then the sender &MUST;
     1797   include in each warning-value a warn-date that matches the
     1798   <x:ref>Date</x:ref> header field in the message.
     1801   If a system receives a message with a warning-value that includes a
     1802   warn-date, and that warn-date is different from the <x:ref>Date</x:ref>
     1803   value in the response, then that warning-value &MUST; be deleted from the
     1804   message before storing, forwarding, or using it (preventing the
     1805   consequences of naive caching of Warning header fields). If all of the
     1806   warning-values are deleted for this reason, the Warning header field &MUST;
     1807   be deleted as well.
    25672559  Some requirements regarding production of the <x:ref>Warning</x:ref>
    25682560  header fields have been relaxed, as it is not widely implemented.
    2569   Furthermore, presence of the warn-date component has been made required
    2570   (dropping requirements specific to HTTP/1.0). Finally, the
    2571   <x:ref>Warning</x:ref> header field no longer uses RFC 2047 encoding,
     2561  Furthermore, the <x:ref>Warning</x:ref> header field no longer uses RFC 2047 encoding,
    25722562  nor allows multiple languages, as these aspects were not implemented.
    25732563  (<xref target="header.warning" />)
    26702660<x:ref>warn-date</x:ref> = DQUOTE HTTP-date DQUOTE
    26712661<x:ref>warn-text</x:ref> = quoted-string
    2672 <x:ref>warning-value</x:ref> = warn-code SP warn-agent SP warn-text SP warn-date
     2662<x:ref>warning-value</x:ref> = warn-code SP warn-agent SP warn-text [ SP warn-date
     2663 ]
    28052796<section title="Since draft-ietf-httpbis-p6-cache-23" anchor="changes.since.23">
    2807   Closed issues:
    2808   <list style="symbols">
    2809     <t>
    2810       <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/486"/>:
    2811       "Requiring proxies to process warn-date"
    2812     </t>
    2813   </list>
     2798   None yet.
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