Changeset 530
- Timestamp:
- 05/03/09 08:36:38 (13 years ago)
- File:
-
- 1 edited
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draft-ietf-httpbis/latest-roy/p6-cache.xml
r528 r530 389 389 390 390 <section anchor="response.cacheability" title="Response Cacheability"> 391 <t>A cache &M AY; store a response to any request, provided that: <list style="symbols">391 <t>A cache &MUST-NOT; store a response to any request, unless: <list style="symbols"> 392 392 <t>The request method is defined as being cacheable, and</t> 393 393 <t>the "no-store" cache directive (see <xref target="header.cache-control" />) does not … … 409 409 title="Storing Partial and Incomplete Responses"> 410 410 <t>A cache that receives an incomplete response (for example, with fewer bytes of data 411 than specified in a Content-Length header) &MAY; store the response. However, the412 cache &MUST; treat thisas a partial response &partial;. Partial responses413 &MAY;be combined as described in &combining-byte-ranges;; the result might be a411 than specified in a Content-Length header) can store the response, but &MUST; 412 treat it as a partial response &partial;. Partial responses 413 can be combined as described in &combining-byte-ranges;; the result might be a 414 414 full response or might still be partial. A cache &MUST-NOT; return a partial 415 415 response to a client without explicitly marking it as such using the 206 (Partial … … 424 424 <section anchor="constructing.responses.from.caches" 425 425 title="Constructing Responses from Caches"> 426 <t>For a presented request, a cache &M AY; return a stored response, provided427 that:<list style="symbols">426 <t>For a presented request, a cache &MUST-NOT; return a stored response, unless: 427 <list style="symbols"> 428 428 <t>The presented Request-URI and that of the stored response match (see 429 429 <cref>TBD</cref>), and</t> … … 454 454 <xref target="invalidation.after.updates.or.deletions" />.</t> 455 455 <t>Caches &MUST; use the most recent response (as determined by the Date header) when 456 more than one suitable response is stored. They &MAY;also forward a request with456 more than one suitable response is stored. They can also forward a request with 457 457 "Cache-Control: max-age=0" or "Cache-Control: no-cache" to disambiguate which response to 458 458 use.</t> … … 476 476 explicit expiration times to responses in the belief that the entity is not likely to 477 477 change in a semantically significant way before the expiration time is reached.</t> 478 <t>If an origin server wishes to force a cache to validate every request, it &MAY;478 <t>If an origin server wishes to force a cache to validate every request, it can 479 479 assign an explicit expiration time in the past. This means that the response is always 480 480 stale, so that caches should validate it before using it for subsequent requests. <cref>This wording may cause confusion, because the response may still be served stale.</cref></t> … … 522 522 <section anchor="heuristic.freshness" title="Calculating Heuristic Freshness"> 523 523 <t>If no explicit expiration time is present in a stored response that has a status code 524 of 200, 203, 206, 300, 301 or 410, a heuristic expiration time &MAY;be524 of 200, 203, 206, 300, 301 or 410, a heuristic expiration time can be 525 525 calculated. Heuristics &MUST-NOT; be used for other response status codes. </t> 526 526 <t> When a heuristic is used to calculate freshness lifetime, the cache &SHOULD; … … 604 604 have heuristic expiry calculated, but is not fresh according to the calculations in 605 605 <xref target="expiration.model" />.</t> 606 <t>Caches &MAY; return a stale response if disconnected (i.e., it cannot contact607 the origin server or otherwise find a forward path) or explicitly allowed (e.g.,608 the max-stale request directive; see <xref target="cache-request-directive" />).</t>609 606 <t>Caches &MUST-NOT; return a stale response if it is prohibited by an explicit 610 607 in-protocol directive (e.g., by a "no-store" or "no-cache" cache directive, a … … 612 609 "proxy-revalidate" cache-response-directive; see <xref target="cache-response-directive" 613 610 />). </t> 614 <t>Otherwise, caches &SHOULD-NOT; return stale responses.</t> 611 <t>Caches &SHOULD-NOT; return stale responses unless they are 612 disconnected (i.e., it cannot contact the origin server or otherwise find a forward path) 613 or otherwise explicitly allowed (e.g., the max-stale request directive; see <xref target="cache-request-directive" />)..</t> 615 614 <t>Stale responses &SHOULD; have a Warning header with the 110 warn-code (see <xref 616 615 target="header.warning" />). Likewise, the 112 warn-code &SHOULD; be sent on stale responses if … … 1030 1029 <t>The Cache-Control header field can be extended through the use of one or more 1031 1030 cache-extension tokens, each with an optional value. Informational extensions (those 1032 that do not require a change in cache behavior) &MAY;be added without changing the1031 that do not require a change in cache behavior) can be added without changing the 1033 1032 semantics of other directives. Behavioral extensions are designed to work by acting as 1034 1033 modifiers to the existing base of cache directives. Both the new directive and the … … 1201 1200 </artwork></figure> 1202 1201 1203 <t>Multiple warnings &MAY;be attached to a response (either by the origin server or by1202 <t>Multiple warnings can be attached to a response (either by the origin server or by 1204 1203 a cache), including multiple warnings with the same code number. For example, a server 1205 1204 might provide the same warning with texts in both English and Basque.</t> … … 1268 1267 </t> 1269 1268 <t>199 Miscellaneous warning <list> 1270 <t>The warning text &MAY;include arbitrary information to be presented to a human1269 <t>The warning text can include arbitrary information to be presented to a human 1271 1270 user, or logged. A system receiving this warning &MUST-NOT; take any automated 1272 1271 action, besides presenting the warning to the user.</t> … … 1282 1281 </t> 1283 1282 <t>299 Miscellaneous persistent warning <list> 1284 <t>The warning text &MAY;include arbitrary information to be presented to a human1283 <t>The warning text can include arbitrary information to be presented to a human 1285 1284 user, or logged. A system receiving this warning &MUST-NOT; take any automated 1286 1285 action.</t>
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