Re: i22: ETags on PUT responses

Werner Baumann wrote:
> Julian Reschke wrote:
>>
>> In particular:
>>
>> - E does not apply to Rq
>>
>> - the presence of E in Rs does not necessarily imply that the body 
>> sent with PUT was stored octet-by-octet
>>
>> - E does not depend on the request method, just on URI & selecting 
>> headers
>>
> I wonder what the intended use of this Etag, sent in response to a 
> PUT-request, would be. As the entity, sent in a subsequent GET is not 
> guaranteed to be equal to the body of the PUT-request, not a single 
> client knows the entity. But clients get an entity-tag - for an unknown 
> entity. What are they supposed to use it for?

They can still use it in all kinds of conditional operations. See 
<http://greenbytes.de/tech/webdav/draft-reschke-http-etag-on-write-08.html> 
for examples, and keep in mind that just because a resource supports PUT 
doesn't necessarily mean the server is a replacement for a file server 
-- the storage may be XML based, for instance.

BR, Julian