cache empties itself?

[DHF]

Ricardo Newbery wrote:
> On Apr 7, 2008, at 5:22 PM, Michael S. Fischer wrote:
>
>   
>> Sure, but this is also the sort of content that can be cached back
>> upstream using ordinary HTTP headers.
>>     
>
>
> No, it cannot.  Again, the use case is dynamically-generated content  
> that is subject to change at unpredictable intervals but which is  
> otherwise fairly "static" for some length of time, and where serving  
> stale content after a change is unacceptable.  "Ordinary" HTTP headers  
> just don't solve that use case without unnecessary loading of the  
> backend.
>   
Isn't this what if-modified-since requests are for?  304 not modified is 
a pretty small request/response, though I can understand the tendency to 
want to push it out to the frontend caches.  I would think the 
management overhead of maintaining two seperate expirations wouldn't be 
worth the extra hassle just to save yourself some ims requests to a 
backend.  Unless of course varnish doesn't support ims requests in a 
usable way, I haven't actually tested it myself.

--Dave