Ignore:
Timestamp:
01/10/12 01:14:48 (8 years ago)
Author:
fielding@…
Message:

(editorial) move selected representation fields to response header fields

File:
1 edited

Legend:

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

    r1918 r1920  
    529529</section>
    530530
    531 <section title="Selected Representation Header Fields" anchor="selected.representation">
    532 <t><iref primary="true" item="selected representation"/>
    533    We use the term "<x:dfn>selected representation</x:dfn>" to refer to the
    534    the current representation of a target resource that would have been
    535    selected in a successful response if the same request had used the
    536    method GET and excluded any conditional request header fields.
    537 </t>
    538 <t>
    539    Additional header fields define metadata about the selected
    540    representation, which might differ from the representation included
    541    in the message for responses to some state-changing methods.
    542    The following header fields are defined as selected representation
    543    metadata:
    544 </t>
    545 <texttable align="left">
    546   <ttcol>Header Field Name</ttcol>
    547   <ttcol>Defined in...</ttcol>
    548 
    549   <c>ETag</c> <c>&header-etag;</c>
    550   <c>Last-Modified</c> <c>&header-last-modified;</c>
    551 </texttable>
    552 </section>
    553 
    554531<section title="Representation Data" anchor="representation.data">
    555532  <x:anchor-alias value="representation-data"/>
     
    32613238  <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol>
    32623239
     3240  <c>Age</c> <c>&header-age;</c>
     3241  <c>Date</c> <c><xref target="header.date"/></c>
    32633242  <c>Location</c> <c><xref target="header.location"/></c>
    32643243  <c>Retry-After</c> <c><xref target="header.retry-after"/></c>
    32653244</texttable>
     3245
     3246<section title="Date" anchor="header.date">
     3247  <iref primary="true" item="Date header field" x:for-anchor=""/>
     3248  <x:anchor-alias value="Date"/>
     3249<t>
     3250   The "Date" header field represents the date and time at which
     3251   the message was originated, having the same semantics as the Origination
     3252   Date Field (orig-date) defined in <xref target="RFC5322" x:fmt="of" x:sec="3.6.1"/>.
     3253   The field value is an HTTP-date, as defined in <xref target="http.date"/>;
     3254   it &MUST; be sent in rfc1123-date format.
     3255</t>
     3256<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Date"/>
     3257  <x:ref>Date</x:ref> = <x:ref>HTTP-date</x:ref>
     3258</artwork></figure>
     3259<t>
     3260   An example is
     3261</t>
     3262<figure><artwork type="example">
     3263  Date: Tue, 15 Nov 1994 08:12:31 GMT
     3264</artwork></figure>
     3265<t>
     3266   Origin servers &MUST; include a Date header field in all responses,
     3267   except in these cases:
     3268  <list style="numbers">
     3269      <t>If the response status code is <x:ref>100 (Continue)</x:ref> or
     3270         <x:ref>101 (Switching Protocols)</x:ref>, the response &MAY; include a
     3271         Date header field, at the server's option.</t>
     3272
     3273      <t>If the response status code conveys a server error, e.g., <x:ref>500
     3274         (Internal Server Error)</x:ref> or <x:ref>503 (Service Unavailable)</x:ref>,
     3275         and it is inconvenient or impossible to generate a valid Date.</t>
     3276
     3277      <t>If the server does not have a clock that can provide a
     3278         reasonable approximation of the current time, its responses
     3279         &MUST-NOT; include a Date header field.</t>
     3280  </list>
     3281</t>
     3282<t>
     3283   A received message that does not have a Date header field &MUST; be
     3284   assigned one by the recipient if the message will be cached by that
     3285   recipient.
     3286</t>
     3287<t>
     3288   Clients can use the Date header field as well; in order to keep request
     3289   messages small, they are advised not to include it when it doesn't convey
     3290   any useful information (as is usually the case for requests that do not
     3291   contain a payload).
     3292</t>
     3293<t>
     3294   The HTTP-date sent in a Date header field &SHOULD-NOT; represent a date and
     3295   time subsequent to the generation of the message. It &SHOULD; represent
     3296   the best available approximation of the date and time of message
     3297   generation, unless the implementation has no means of generating a
     3298   reasonably accurate date and time. In theory, the date ought to
     3299   represent the moment just before the payload is generated. In
     3300   practice, the date can be generated at any time during the message
     3301   origination without affecting its semantic value.
     3302</t>
     3303</section>
    32663304
    32673305<section title="Location" anchor="header.location">
     
    33673405</section>
    33683406
    3369 <section title="Cache-related" anchor="response.cache.related">
    3370 <t>
    3371    Cache-related response header fields provide metadata about the message
    3372    in order to assist downstream caches.
     3407<section title="Selected Representation Header Fields" anchor="selected.representation">
     3408<t><iref primary="true" item="selected representation"/>
     3409   We use the term "<x:dfn>selected representation</x:dfn>" to refer to the
     3410   the current representation of a target resource that would have been
     3411   selected in a successful response if the same request had used the
     3412   method GET and excluded any conditional request header fields.
     3413</t>
     3414<t>
     3415   Additional header fields define metadata about the selected
     3416   representation, which might differ from the representation included
     3417   in the message for responses to some state-changing methods.
     3418   The following header fields are defined as selected representation
     3419   metadata:
    33733420</t>
    33743421<texttable align="left">
    3375   <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol>
    3376 
    3377   <c>Age</c> <c>&header-age;</c>
    3378   <c>Date</c> <c><xref target="header.date"/></c>
     3422  <ttcol>Header Field Name</ttcol>
     3423  <ttcol>Defined in...</ttcol>
     3424
     3425  <c>ETag</c> <c>&header-etag;</c>
     3426  <c>Last-Modified</c> <c>&header-last-modified;</c>
    33793427  <c>Vary</c> <c><xref target="header.vary"/></c>
    33803428</texttable>
    3381 
    3382 <section title="Date" anchor="header.date">
    3383   <iref primary="true" item="Date header field" x:for-anchor=""/>
    3384   <x:anchor-alias value="Date"/>
    3385 <t>
    3386    The "Date" header field represents the date and time at which
    3387    the message was originated, having the same semantics as the Origination
    3388    Date Field (orig-date) defined in <xref target="RFC5322" x:fmt="of" x:sec="3.6.1"/>.
    3389    The field value is an HTTP-date, as defined in <xref target="http.date"/>;
    3390    it &MUST; be sent in rfc1123-date format.
    3391 </t>
    3392 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Date"/>
    3393   <x:ref>Date</x:ref> = <x:ref>HTTP-date</x:ref>
    3394 </artwork></figure>
    3395 <t>
    3396    An example is
    3397 </t>
    3398 <figure><artwork type="example">
    3399   Date: Tue, 15 Nov 1994 08:12:31 GMT
    3400 </artwork></figure>
    3401 <t>
    3402    Origin servers &MUST; include a Date header field in all responses,
    3403    except in these cases:
    3404   <list style="numbers">
    3405       <t>If the response status code is <x:ref>100 (Continue)</x:ref> or
    3406          <x:ref>101 (Switching Protocols)</x:ref>, the response &MAY; include a
    3407          Date header field, at the server's option.</t>
    3408 
    3409       <t>If the response status code conveys a server error, e.g., <x:ref>500
    3410          (Internal Server Error)</x:ref> or <x:ref>503 (Service Unavailable)</x:ref>,
    3411          and it is inconvenient or impossible to generate a valid Date.</t>
    3412 
    3413       <t>If the server does not have a clock that can provide a
    3414          reasonable approximation of the current time, its responses
    3415          &MUST-NOT; include a Date header field.</t>
    3416   </list>
    3417 </t>
    3418 <t>
    3419    A received message that does not have a Date header field &MUST; be
    3420    assigned one by the recipient if the message will be cached by that
    3421    recipient.
    3422 </t>
    3423 <t>
    3424    Clients can use the Date header field as well; in order to keep request
    3425    messages small, they are advised not to include it when it doesn't convey
    3426    any useful information (as is usually the case for requests that do not
    3427    contain a payload).
    3428 </t>
    3429 <t>
    3430    The HTTP-date sent in a Date header field &SHOULD-NOT; represent a date and
    3431    time subsequent to the generation of the message. It &SHOULD; represent
    3432    the best available approximation of the date and time of message
    3433    generation, unless the implementation has no means of generating a
    3434    reasonably accurate date and time. In theory, the date ought to
    3435    represent the moment just before the payload is generated. In
    3436    practice, the date can be generated at any time during the message
    3437    origination without affecting its semantic value.
    3438 </t>
    3439 </section>
    34403429
    34413430<section anchor="header.vary" title="Vary">
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