- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Tue, 06 Apr 2010 17:37:22 +0200
- To: Jamie Lokier <jamie@shareable.org>
- CC: Yves Lafon <ylafon@w3.org>, nathan@webr3.org, HTTP Working Group <ietf-http-wg@w3.org>
On 06.04.2010 17:22, Jamie Lokier wrote: > ... > Changing attribute order *is* making a different representation. > > Thus Julian's idea of when to use the same weak etags is recommended > against by Yves. > ... Nope. It is a different representation (in that it may vary over time), but I wouldn't call it a different representation of a different *resource*. > I happen to agree with Julian(*), but I'm really interested in when > Yves thinks it is appropriate to use same weak etags, given the > statement that it's unsafe to use them for different representations. > > -- Jamie > > ps. (*) Why my pov matches Julian's: > > Instead of changing attribute order, what about different output > encodings at serialization time? Note that the *input* XML database > might not even *have* a character encoding. I think that is in the > same category as attribute order, because the underlying XML resource, > right down to the individual characters, is unchanged, although it's > clearly not binary identical. Absolutely. > If the underlying resource is the same for different character > encodings (Content-Type charset=), in what way is compression > (Content-Encoding) semantically different? I think it isn't. I'm not sure, and I'm even not sure the answer matters. We will need to change text to address <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/101> (please review the long history of this issue). In particular, Roy said: > A weak entity tag SHOULD change whenever the origin server considers prior representations to be unacceptable as a substitute for the current representation. In other words, an entity tag SHOULD change whenever the origin server wants caches to invalidate old responses. Best regards, Julian
Received on Tuesday, 6 April 2010 15:37:57 UTC