Changeset 2111 for draft-ietf-httpbis/latest/p2-semantics.xml

Timestamp:

11/01/13 08:39:05 (8 years ago)

Author:

fielding@…

Message:

ensure that a validator field sent in response to a successful PUT means something useful; addresses #22 (along with [2110])

File:

• draft-ietf-httpbis/latest/p2-semantics.xml (modified) (1 diff)

draft-ietf-httpbis/latest/p2-semantics.xml

@@ -1443 +1443 @@
 </t>
 <t>
+   An origin server &MUST-NOT; send a validator header field
+   (<xref target="response.validator"/>), such as an <x:ref>ETag</x:ref> or
+   <x:ref>Last-Modified</x:ref> field, in a successful response to PUT unless
+   the request's representation data was saved without any transformation
+   applied to the body (i.e., the resource's new representation data is
+   identical to the representation data received in the PUT request) and the
+   validator field value reflects the new representation.
+   This requirement allows a user agent to know when the representation body
+   it has in memory remains current as a result of the PUT, thus not in need
+   of retrieving again from the origin server, and that the new validator(s)
+   received in the response can be used for future conditional requests in
+   order to prevent accidental overwrites.
+</t>
+<t>
    The fundamental difference between the POST and PUT methods is
    highlighted by the different intent for the enclosed representation.