Changeset 496


Ignore:
Timestamp:
Mar 3, 2009, 10:58:09 PM (11 years ago)
Author:
mnot@…
Message:

clean up validation model

File:
1 edited

Legend:

Unmodified
Added
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  • draft-ietf-httpbis/latest-roy/p6-cache.xml

    r495 r496  
    640640
    641641      <section anchor="validation.model" title="Validation Model">
    642         <t>When a cache has a stale response that it would like to use, it &SHOULD; first check
    643           with the origin server (or possibly an intermediate cache) to see if
    644           it is still usable. This is called "validating" or "revalidating" the stored response.</t>
    645         <t>HTTP's conditional request mechanism, defined in &conditional;, is used to avoid
    646           retransmitting the response payload when the stored response is valid. When a stored
    647           response includes one or more "cache validators", such as the field values of an ETag or
    648           Last-Modified header field, then a validating GET request &SHOULD; be made conditional
    649           to those field values; a 304 (Not Modified) response status code indicates that the stored
     642        <t>Checking with the origin server to see if a stale or otherwise unusable cached response
     643        can be reused is called "validating" or "revalidating." Doing so potentially avoids
     644        the overhead of retransmitting the response body when the stored response is valid.</t>
     645        <t>HTTP's conditional request mechanism &conditional; is used for this purpose. When a stored
     646          response includes one or more validators, such as the field values of an ETag or
     647          Last-Modified header field, then a validating request &SHOULD; be made conditional
     648          to those field values.</t>
     649         <t>A 304 (Not Modified) response status code indicates that the stored
    650650          response can be updated and reused; see <xref target="combining.headers"/>.</t>
    651         <t>If the cache receives a full response (i.e., one with payload), it is used to satisfy the
    652         request and replace the stored response.</t>
     651        <t>If instead the cache receives a full response (i.e., one with a response body), it is used to satisfy the
     652        request and replace the stored response. <cref>Should there be a requirement here?</cref></t>
    653653        <t>If a cache receives a 5xx response while attempting to validate a response, it &MAY;
    654654          either forward this response to the requesting client, or act as if the server failed to
    655655          respond. In the latter case, it &MAY; return a previously stored response unless the
    656656          stored response includes the "must-revalidate" cache directive (see <xref
    657             target="cache-response-directive" />).</t>
     657            target="serving.stale.responses" />).</t>
    658658      </section>
    659659
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