On mandag 2. august 2004, 17:06, Tod Harter wrote: > In the absence of an Expires: header doesn't the ETag essentially > tell all? If you issue a HEAD request and get back the same ETag as > whatever is cached then you shouldn't need to refetch the resource, > correct?
Yup, but the point is that you shouldn't issue a HEAD request. It would have been superfluous if they just had used Expires (or Control-cache: max-age), for what it is for.... The distinction is made a big point of in HTTP/1.1, the second paragraph of Section 13: Caching would be useless if it did not significantly improve performance. The goal of caching in HTTP/1.1 is to eliminate the need to send requests in many cases, and to eliminate the need to send full responses in many other cases. The former reduces the number of network round-trips required for many operations; we use an "expiration" mechanism for this purpose (see section 13.2). The latter reduces network bandwidth requirements; we use a "validation" mechanism for this purpose (see section 13.3). It isn't quite clear what slashdot means when they say that you shouldn't access the file, but I think it means they don't want you to throw any requests at them... Actually, what I found was that RSS has fields for how often you should update, and /. wants you to parse the RSS and figure that out. Now, that's Harmful, when HTTP allready has a much better way to handle stuff like that. Not a caching proxy in the entire world is going to parse RSS to find out when to update, but they allready respect Expires. But I guess a Provider is the solution, and the Provider actually has to parse RSS and act accordingly... Cheers, Kjetil -- Kjetil Kjernsmo Astrophysicist/IT Consultant/Skeptic/Ski-orienteer/Orienteer/Mountaineer [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] Homepage: http://www.kjetil.kjernsmo.net/ OpenPGP KeyID: 6A6A0BBC --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
