Ignore:
Timestamp:
14/09/13 05:30:06 (7 years ago)
Author:
fielding@…
Message:

remind folks why weak or strong comparison is used; addresses #495

File:
1 edited

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  • draft-ietf-httpbis/latest/p4-conditional.html

    r2389 r2390  
    704704      </p>
    705705      <p id="rfc.section.2.1.p.9">A "use" of a validator occurs when either a client generates a request and includes the validator in a precondition or when
    706          a server compares two validators. Weak validators are only usable in contexts that do not depend on exact equality of the
    707          representation data. Strong validators are usable and preferred for all conditional requests, including cache validation,
    708          partial content ranges, and "lost update" avoidance.
     706         a server compares two validators. Weak validators are only usable for use cases that do not depend on exact equality of the
     707         representation data, such as cache validation, or for limiting the scope of web traversals to recently changed representations.
     708         Strong validators are usable and preferred for all conditional requests, including cache validation, partial content ranges,
     709         and "lost update" avoidance.
    709710      </p>
    710711      <div id="rfc.iref.l.1"></div>
     
    941942         the target resource that has an entity-tag matching a member of the list of entity-tags provided in the field-value.
    942943      </p>
    943       <p id="rfc.section.3.1.p.2">A recipient <em class="bcp14">MUST</em> use the strong comparison function when comparing entity-tags for If-Match (<a href="#entity.tag.comparison" title="Comparison">Section&nbsp;2.3.2</a>).
     944      <p id="rfc.section.3.1.p.2">A recipient <em class="bcp14">MUST</em> use the strong comparison function when comparing entity-tags for If-Match (<a href="#entity.tag.comparison" title="Comparison">Section&nbsp;2.3.2</a>), since the client intends this precondition to prevent the method from being applied if there have been any changes to the
     945         representation data.
    944946      </p>
    945947      <div id="rfc.figure.u.8"></div><pre class="inline"><span id="rfc.iref.g.7"></span>  <a href="#header.if-match" class="smpl">If-Match</a> = "*" / 1#<a href="#header.etag" class="smpl">entity-tag</a>
     
    968970         target resource that has an entity-tag matching a member of the list of entity-tags provided in the field-value.
    969971      </p>
    970       <p id="rfc.section.3.2.p.2">A recipient <em class="bcp14">MUST</em> use the weak comparison function when comparing entity-tags for If-None-Match (<a href="#entity.tag.comparison" title="Comparison">Section&nbsp;2.3.2</a>).
     972      <p id="rfc.section.3.2.p.2">A recipient <em class="bcp14">MUST</em> use the weak comparison function when comparing entity-tags for If-None-Match (<a href="#entity.tag.comparison" title="Comparison">Section&nbsp;2.3.2</a>), since weak entity-tags can be used for cache validation even if there have been changes to the representation data.
    971973      </p>
    972974      <div id="rfc.figure.u.10"></div><pre class="inline"><span id="rfc.iref.g.8"></span>  <a href="#header.if-none-match" class="smpl">If-None-Match</a> = "*" / 1#<a href="#header.etag" class="smpl">entity-tag</a>
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