Support for If-None-Match header.

Craig Servin cservin-varnish at
Mon Jan 23 16:02:00 CET 2017

Hi Jan,

You might want to consider using the libvmod-xkey and then having 
backend changes just tell varnish to invalidate based on that secondary 



On 2017-01-23 06:56, Jan Hugo Prins | BetterBe wrote:
> Hello,
> We are currently investigating the use of Varnish for our
> infrastructure. In the software we build, we depend on the
> If-None-Match header and the use of ETAG's.
> The API we have created creates mainly JSON objects, and they differ
> in size from a few hundreds of bytes to several megabytes. A lot of
> these JSON objects are perfectly suited for caching, until someone
> changes a parameter and this can happen at any moment. That is also
> why we keep a record of all ETAG's and we invalidate them when needed.
> What we would like to do is cache created JSON object in front of our
> production environment and when someone requests the same calculation
> that someone else has requested before and the ETAG is still valid,
> send out the cached object. But this basicly implies the following
> workflow:

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