- From: Paul Burchard <burchard@horizon.math.utah.edu>
- Date: Thu, 12 Jan 95 13:23:14 -0700
- To: cwilson@spry.com, allocca@openmarket.com
- Cc: Multiple recipients of list <www-talk@www0.cern.ch>, M.J.Cox@bradford.ac.uk, fielding@avron.ICS.UCI.EDU, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com, "Daniel W. Connolly" <connolly@hal.com>
Chris Wilson <cwilson@spry.com> writes: > Bill Allocca <allocca@OpenMarket.com> writes: > >Is there any way in HTTP for a Server to automatically update a page > >without requiring the user of the client to click on anything? > > Because of the other problems that you noted (namely, > that clients are not required to automatically reload a > document when it passes the Expired time- in fact, it > would be detrimental to do so), > > >there are cases where a page is valid only once -- > >they expire immediately and the client shouldn't get > >them again. The current HTTP draft spec *does* specifically interpret "Expires:" as a client directive to automatically reload the data at that time -- i.e. expiry interpreted as "data expiry". However, along with Dan Connolly, and others that Bill Allocca mentions, I also originally interpreted Expires as a server guarantee to deliver constant data up to that time -- i.e. expiry interpreted as "URL expiry". My own example of "URL expiry" without "data expiry" was that of custom inline images inside FORM-generated documents, which get deleted from the server immediately upon retrieval. According to the HTTP draft spec, I should not tell the client to "expire" these images. > I would propose an "Expires-Auto-Update:" field - with a > value of "yes" or "no", default "no" in case of the header > line not appearing - which would force the client to > automatically update the page. Since, "data expiry" and "URL expiry" are independent issues, as the examples have shown, it seems like we really need two independent time headers, say "Data-Expires:" and "URI-Expires:". According to the current HTTP spec draft, "Expires:" means "Data-Expires:", and this does seem like the more generally useful one. -------------------------------------------------------------------- Paul Burchard <burchard@math.utah.edu> ``I'm still learning how to count backwards from infinity...'' --------------------------------------------------------------------
Received on Thursday, 12 January 1995 12:48:43 UTC