what's the problem that requires supplying a freshness parameter?

I may be dense, but I don't see what problem is solved by requiring
that HTTP 1.1 servers supply a freshness parameter.

I thought the problem you were trying to solve was one of:

1.  some caches have out of date material...
2.   content providers don't know what caches will do...

I think I understand the proposal.

I don't see how the proposal solves either of the the problems.

Basically, if 
- the content author doesn't know freshness, 
- the server administrator doesn't know freshness,
- and the cache wants to be agressive and cache things without
   contacting the origin server, even though they're not guaranteed fresh,

then there's no way to guarantee freshness. You can't solve the first
problem. Some caches will continue to have out of date material.  As
for problem 2, sure, content providers will know what caches will do,
if they care. But on the other hand, they could know what caches would
do anyway, just by supplying an Expires: now.  So how does the
proposal change anything?

For the first problem, the proposal just moves the blame around. You
can either blame the author, the server author, the server
administrator, the cache, or the user, and now, you'll be able to
blame the server administrator.

Received on Wednesday, 10 January 1996 08:44:07 UTC