Conditional GETs

Ricardo Newbery ric at
Sun Jul 29 01:09:41 CEST 2007

On Jul 28, 2007, at 3:47 PM, Ricardo Newbery wrote:

> On Jul 28, 2007, at 1:08 AM, Dag-Erling Smørgrav wrote:
>> Ricardo Newbery <ric at> writes:
>>> I'm a little unsure as I didn't hear an affirmation to my  
>>> question...
>>> so does Varnish respect max-age and s-maxage in the response?
>> Yes, see r1386.
> Ahh... okay.  Thanks.
> Now back to the question about INM requests.  After some thought, I
> guess I'm less interested about trying to replicate INM in VCL but am
> still interested in how Varnish refreshes it's own cache.
> Since Varnish respects the maxage controls, this implies that when
> the next request comes in after expiry it will generate a conditional
> request (if Last-Modified is set) to refresh it's cache.  Correct?
> But no INM to the backend will ever be generated regardless of the
> presence of an ETag.  Correct?
> In my own use case (Plone CMS), etags are leveraged as a convenient
> index hash for the server's pagecache in RAM.  But in order to serve
> from the pagecache, we need an INM in the request.  So I'm trying to
> understand the implications of Varnish's ETag behavior on this  
> process.
> Ric

Correction.  Upon reflection the explanation of the server pagecache  
behavior didn't sound right.  So I checked the code, and I was wrong  
--- the pagecache doesn't need an INM; it regenerates the ETag based  
on the request before querying the pagecache.


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