Re: Definitions: caches, history buffers, etc.

How's this sound?

A client or proxy cache:
	exists to model the origin servers' state (which was observed
	sometime in the past at t sub 0) at t sub now.

A client history buffer:
	exists to model the user's interaction history.  Hence use
	of the history list, or back button to return to a page
	with which the user last interacted at time t sub 0,
	should result in a state fundamentally similar to the one
	in which they were at t sub 0 (and forward should bring them
	back to t sub now)

Even if the server (and hence the cache) would provide different content
for the URL at t sub now than it did at t sub 0, the history buffer should
present the content at t sub 0.  Furthermore, if there is state associated
with that page, such as <FORM>s, Director Movies, Java Applets, etc., it
should be restored so that the user is presented with the page in the state
of last interaction.

There's a third concept that hasn't been touched upon - the distinction
between global history and the history buffer.  I feel pretty strongly
that the history buffer strongly implies consistency with the user's
navigational clickstream, so if there are multiple windows available,
and the following sequence occurs:
	Page A displayed in window 1
	Page B displayed in window 2
	user follows link to C in window 2
	Page C displayed in window 2
	user follows link to D in window 1
	Page D displayed in window 1
Use of the Back button in window 1 can result in either:
	a) Page A displayed in window 1
		-or-
	b) window 2 raised to the top, still with Page C
		-but not-
	c) Page C displayed in window 1

-Dave

Received on Tuesday, 9 January 1996 21:39:51 UTC