Changeset 496
- Timestamp:
- 04/03/09 06:58:09 (13 years ago)
- File:
-
- 1 edited
Legend:
- Unmodified
- Added
- Removed
-
draft-ietf-httpbis/latest-roy/p6-cache.xml
r495 r496 640 640 641 641 <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 check643 with the origin server (or possibly an intermediate cache) to see if644 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 avoid646 re transmitting the response payload when the stored response is valid. When a stored647 response includes one or more "cache validators", such as the field values of an ETag or648 Last-Modified header field, then a validating GET request &SHOULD; be made conditional649 to those field values; a304 (Not Modified) response status code indicates that the stored642 <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 650 650 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 the652 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> 653 653 <t>If a cache receives a 5xx response while attempting to validate a response, it &MAY; 654 654 either forward this response to the requesting client, or act as if the server failed to 655 655 respond. In the latter case, it &MAY; return a previously stored response unless the 656 656 stored response includes the "must-revalidate" cache directive (see <xref 657 target=" cache-response-directive" />).</t>657 target="serving.stale.responses" />).</t> 658 658 </section> 659 659
Note: See TracChangeset
for help on using the changeset viewer.