Ignore:
Timestamp:
01/10/12 11:58:46 (8 years ago)
Author:
fielding@…
Message:

Clean up content codings and Content-Encoding sections

File:
1 edited

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Unmodified
Added
Removed
  • draft-ietf-httpbis/latest/p2-semantics.xml

    r1926 r1927  
    511511
    512512<section title="Content Codings" anchor="content.codings">
     513  <iref primary="true" item="content coding"/>
     514  <iref primary="true" item="compress (content coding)"/>
     515  <iref primary="true" item="x-compress (content coding)"/>
     516  <iref primary="true" item="deflate (content coding)"/>
     517  <iref primary="true" item="gzip (content coding)"/>
     518  <iref primary="true" item="x-gzip (content coding)"/>
    513519  <x:anchor-alias value="content-coding"/>
    514520<t>
     
    524530</artwork></figure>
    525531<t>
    526    All content-coding values are case-insensitive. HTTP/1.1 uses
    527    content-coding values in the <x:ref>Accept-Encoding</x:ref>
    528    (<xref target="header.accept-encoding"/>) and <x:ref>Content-Encoding</x:ref>
    529    (<xref target="header.content-encoding"/>) header fields. Although the value
    530    describes the content-coding, what is more important is that it
    531    indicates what decoding mechanism will be required to remove the
    532    encoding.
    533 </t>
    534 <t>
    535    compress<iref item="compress (Coding Format)"/>
    536   <list>
    537     <t>
    538       See &compress-coding;.
    539     </t>
    540   </list>
    541 </t>
    542 <t>
    543    deflate<iref item="deflate (Coding Format)"/>
    544   <list>
    545     <t>
    546       See &deflate-coding;.
    547     </t>
    548   </list>
    549 </t>
    550 <t>
    551    gzip<iref item="gzip (Coding Format)"/>
    552   <list>
    553     <t>
    554       See &gzip-coding;.
    555     </t>
    556   </list>
     532   All content-coding values are case-insensitive and &SHOULD; be registered
     533   within the HTTP Content Coding registry, as defined in
     534   <xref target="content.coding.registry"/>. They are used in the
     535   <x:ref>Accept-Encoding</x:ref> (<xref target="header.accept-encoding"/>)
     536   and <x:ref>Content-Encoding</x:ref> (<xref target="header.content-encoding"/>)
     537   header fields.
     538</t>
     539<t>
     540   The following content-coding values are defined by this specification:
     541   <list>
     542    <t>compress (and x-compress): See &compress-coding;.</t>
     543    <t>deflate: See &deflate-coding;.</t>
     544    <t>gzip (and x-gzip): See &gzip-coding;.</t>
     545   </list>
    557546</t>
    558547</section>
     
    562551  <x:anchor-alias value="Content-Encoding"/>
    563552<t>
    564    The "Content-Encoding" header field indicates what content-codings
    565    have been applied to the representation beyond those inherent in the media
    566    type, and thus what decoding mechanisms have to be applied in order to obtain
    567    the media-type referenced by the <x:ref>Content-Type</x:ref> header field.
    568    Content-Encoding is primarily used to allow a representation to be
     553   The "Content-Encoding" header field indicates what content codings
     554   have been applied to the representation, beyond those inherent in the media
     555   type, and thus what decoding mechanisms have to be applied in order to
     556   obtain data in the media type referenced by the <x:ref>Content-Type</x:ref>
     557   header field.
     558   Content-Encoding is primarily used to allow a representation's data to be
    569559   compressed without losing the identity of its underlying media type.
    570560</t>
     
    573563</artwork></figure>
    574564<t>
    575    Content codings are defined in <xref target="content.codings"/>. An example of its use is
     565   An example of its use is
    576566</t>
    577567<figure><artwork type="example">
     
    579569</artwork></figure>
    580570<t>
    581    The content-coding is a characteristic of the representation.
    582    Typically, the representation data is stored with this
    583    encoding and is only decoded before rendering or analogous usage.
    584    However, a transforming proxy &MAY; modify the content-coding if the
     571   If multiple encodings have been applied to a representation, the content
     572   codings &MUST; be listed in the order in which they were applied.
     573   Additional information about the encoding parameters &MAY; be provided
     574   by other header fields not defined by this specification.
     575</t>
     576<t>
     577   Unlike Transfer-Encoding (&header-transfer-encoding;), the codings listed
     578   in Content-Encoding are a characteristic of the representation; the
     579   representation is defined in terms of the coded form, and all other
     580   metadata about the representation is about the coded form unless otherwise
     581   noted in the metadata definition. Typically, the representation is only
     582   decoded just prior to rendering or analogous usage.
     583</t>
     584<t>
     585   A transforming proxy &MAY; modify the content coding if the
    585586   new coding is known to be acceptable to the recipient, unless the
    586587   "no-transform" cache-control directive is present in the message.
     
    590591   that is always compressed, then that encoding would not be restated as
    591592   a Content-Encoding even if it happens to be the same algorithm as one
    592    of the content-codings.  Such a content-coding would only be listed if,
     593   of the content codings.  Such a content coding would only be listed if,
    593594   for some bizarre reason, it is applied a second time to form the
    594595   representation.  Likewise, an origin server might choose to publish the
     
    598599   handling of each response (e.g., open a "Save as ..." dialog instead of
    599600   automatic decompression and rendering of content).
    600 </t>
    601 <t>
    602    A representation that has a content-coding applied to it &MUST; include
    603    a Content-Encoding header field that lists the content-coding(s) applied.
    604 </t>
    605 <t>
    606    If multiple encodings have been applied to a representation, the content
    607    codings &MUST; be listed in the order in which they were applied.
    608    Additional information about the encoding parameters &MAY; be provided
    609    by other header fields not defined by this specification.
    610601</t>
    611602<t>
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