Idea: Using the SPDY protocol to improve Tor performance

Steven J. Murdoch tor+Steven.Murdoch at
Thu Feb 4 20:54:23 UTC 2010

Hi Carsten,

On Thu, Feb 04, 2010 at 12:13:03AM +0100, Carsten Krüger wrote:
> it's questionable is SPDY is usefull at all.

Google's benchmarks show a ~50% speed-up, and better performance in
high-latency environments. Using it in the way I suggested is
different from Google's tests, so I am not certain how much an
improvement SPDY would give, but I would like to perform some
experiments before dismissing it.

> Normally only few things changes if you visit a website seconds time
> (stylesheets, javascriptlib, pics, etc. are static).
> They are not delivered two times via http because they are cached in
> browser.
> SPDY didn't support any caching so a client that visits websites more
> than once has to load everything again. Very bad.
> If the caching problem isn't solved SPDY via tor would be worse than
> http I think.

SPDY is a transport layer for HTTP, and so has no effect on caching.
All the Cache-Control parameters supported by HTTP work with SPDY.
Browsers don't need to change their caching behaviour either.

Server push does need to be handled carefully with respect to caching,
because it would be silly to push a resource to a client, when the
client has a copy. However, all the other features of SPDY should work
just as well with caching on as with it off.



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