Changeset 1927 for draft-ietf-httpbis/latest/p2-semantics.xml
- Timestamp:
- 01/10/12 11:58:46 (10 years ago)
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draft-ietf-httpbis/latest/p2-semantics.xml
r1926 r1927 511 511 512 512 <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)"/> 513 519 <x:anchor-alias value="content-coding"/> 514 520 <t> … … 524 530 </artwork></figure> 525 531 <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> 557 546 </t> 558 547 </section> … … 562 551 <x:anchor-alias value="Content-Encoding"/> 563 552 <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 569 559 compressed without losing the identity of its underlying media type. 570 560 </t> … … 573 563 </artwork></figure> 574 564 <t> 575 Content codings are defined in <xref target="content.codings"/>.An example of its use is565 An example of its use is 576 566 </t> 577 567 <figure><artwork type="example"> … … 579 569 </artwork></figure> 580 570 <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 585 586 new coding is known to be acceptable to the recipient, unless the 586 587 "no-transform" cache-control directive is present in the message. … … 590 591 that is always compressed, then that encoding would not be restated as 591 592 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, 593 594 for some bizarre reason, it is applied a second time to form the 594 595 representation. Likewise, an origin server might choose to publish the … … 598 599 handling of each response (e.g., open a "Save as ..." dialog instead of 599 600 automatic decompression and rendering of content). 600 </t>601 <t>602 A representation that has a content-coding applied to it &MUST; include603 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 content607 codings &MUST; be listed in the order in which they were applied.608 Additional information about the encoding parameters &MAY; be provided609 by other header fields not defined by this specification.610 601 </t> 611 602 <t>
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