cache empties itself?

[Ricardo Newbery]

On Apr 7, 2008, at 5:22 PM, Michael S. Fischer wrote:

> On Fri, Apr 4, 2008 at 3:31 PM, Ricardo Newbery <ric at digitalmarbles.com 
> > wrote:
>
>>>> Again, "static" content isn't only the stuff that is served from
>>>> filesystems in the classic static web server scenario.  There are  
>>>> plenty
>> of
>>>> "dynamic" applications that process content from database --  
>>>> applying
>> skins
>>>> and compositing multiple elements into a single page while  
>>>> filtering
>> every
>>>> element or otherwise applying special processing based on a user's
>> access
>>>> privileges.  An example of this is a dynamic content management  
>>>> system
>> like
>>>> Plone or Drupal.  In many cases, these "dynamic" responses are  
>>>> fairly
>>>> "static" for some period of time but there is still a definite
>> performance
>>>> hit, especially under load
>
>> In any case, both of these examples, Plone and Drupal, can indeed  
>> cache the
>> output "locally" but that is still not as fast as placing a  
>> dedicated cache
>> server in front.  It's almost always faster to have a dedicated
>> single-purpose process do something instead of cranking up the hefty
>> machinery for requests that can be adequately served by the lighter  
>> process.
>
> 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.


> Still waiting for that compelling case that requires independent cache
> configuration,


This is an odd response.  I've already pointed out at least one common  
use case which can benefit from "independent" cache configuration.  Is  
that not compelling enough?  It might help if you can explain your  
criteria for what qualifies as "compelling".

Ric