Q: Caching Hierachy

[Christoph]

I need to build a hierachical caching plattform. The Goal is, to have
multiple frontends that will expire in sync. 

Currently we cascade a pool of Cacher in front of a single Intermediate
Cache. The Front-Cacher will honor any "Age"-Header it will retrieve
from the Intermediate. 

So cacher-1 will be asked for a document at 10:00. It will ask the
intermediate, this one will ask the backend. 

Next cacher-2 will be asked for a document at 10:01. It will ask the
intermediate, intermediate will return the document with an age header
of 60 Seconds. 

After max-age = 300 Seconds, the document will be invalid on cacher-1
and cacher-2. 

Is this possible with varnish? 

Greetings
   Christoph