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Re: Expires, Last-Modified, Pragma: no-cache etc.

From: Henrik Frystyk Nielsen <frystyk@w3.org>
Date: Wed, 16 Aug 1995 19:09:26 -0400
Message-Id: <9508162309.AA06942@www20>
To: David Morris <dwm@shell.portal.com>
Cc: http working group <http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com>

dwm@shell.portal.com said:
> I believe this is the wrong design.  The user *MUST* be able to 
> always flip the page backward and see the same material just viewed.  
> THis is a critical user interface usability issue. Within the same 
> session/ instance of UAgent execution. I believe it would be/is wrong 
> to silently refresh a document during history navigation when the 
> history cache has overflowed. I (and many users I know) expect the 
> history to be a record of what I've seen. I would have not objection 
> to a  browser which checked currency and via a non-modal message 
> advised that the history copy wasn't current ("Current copy not 
> current, RELOAD for the latest copy" for example).

I think this is a limited view of the world. The way that I have implemented 
it (yesterday, that is) is to let it be up to the user to choose what action 
to be taken if an expired history object is encountered:

	1) Do nothing at all and show the document

	2) Notify the user that the document is stale but do not refresh it

	3) Do an automatic reload when the document becomes active (visible) to 		   
the user.

This looks like a nice "option menu" to me!

Henrik Frystyk Nielsen, <frystyk@w3.org>
World-Wide Web Consortium, MIT/LCS NE43-356
545 Technology Square, Cambridge MA 02139, USA
Received on Wednesday, 16 August 1995 16:11:48 UTC

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