Changeset 657
- Timestamp:
- 29/07/09 11:27:37 (12 years ago)
- File:
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- 1 edited
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draft-ietf-httpbis/latest/p2-semantics.xml
r655 r657 690 690 <iref item="Idempotent Methods" primary="true"/> 691 691 <t> 692 Methods can also have the property of "idempotence" in that (aside 693 from error or expiration issues) the side-effects of N > 0 identical 694 requests is the same as for a single request. The methods GET, HEAD, 695 PUT and DELETE share this property. Also, the methods OPTIONS and 696 TRACE &SHOULD-NOT; have side effects, and so are inherently idempotent. 697 </t> 698 <t> 699 However, it is possible that a sequence of several requests is non-idempotent, 700 even if all of the methods executed in that sequence are 701 idempotent. (A sequence is idempotent if a single execution of the 702 entire sequence always yields a result that is not changed by a 703 reexecution of all, or part, of that sequence.) For example, a 704 sequence is non-idempotent if its result depends on a value that is 705 later modified in the same sequence. 706 </t> 707 <t> 708 A sequence that never has side effects is idempotent, by definition 709 (provided that no concurrent operations are being executed on the 710 same set of resources). 692 Methods can also have the property of "idempotence" in that, aside 693 from error or expiration issues, the intended effect of multiple 694 identical requests is the same as for a single request. 695 The methods PUT, DELETE, and all safe methods are idempotent. 696 It is important to note that idempotence refers only to changes 697 requested by the client: a server is free to change its state due 698 to multiple requests for the purpose of tracking those requests, 699 versioning of results, etc. 711 700 </t> 712 701 </section>
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