[LINK] RFI: How Does the Do-Not-Cache Instruction Work?

[Adrian Chadd]

On Mon, Aug 11, 2008, Roger Clarke wrote:

> http://www.mnot.net/cache_docs/#META explains the 'Expires' and 
> 'Cache-Control' settings in the HTTP header.  (It's so much easier to 
> read documentation when you know the relevant keywords!!).
> 
> As Jan mentioned, my need is in relation to Google's StreetView.
> 
> The underlying question I'm trying to dig down into is whether 
> StreetView scenes are likely to be cached anywhere, whether on users' 
> machines or on intervening proxy-servers run by ISPs.
> 
> Knowing the answer would make it easier to understand what happens 
> when Google amends an image (e.g. by manually blurring a face) or 
> takes it down.

Give me 3 weeks and I'll try to make Squid cache it.

> Is Adobe Flash content just as capable of being cached as other 
> formats?  I can't immediately see why not.  So I assume it's cached 
> client-side too.

It can be. Its just 'data'..

The important thing to realise is that HTTP/1.1 defines caching AND
-revalidation- methods.

Its completely possible that the content can be cached client-side but
be revalidated every time the content is re-requested by the client.
This way you save lots of bandwidth but still control the content
(ie, can expire it at will.)

I've made rules for Squid to cache Youtube and Google Maps; StreetView is on
my TODO list.




Adrian

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