Re: estimated Content-Length with chunked encoding

On Fri, 14 Nov 2008, Jamie Lokier wrote:

> What about sending "Expect: 100-continue" in the request headers, and 
> waiting for a "100 Continue" response.  If you get one, you _ought_ to be 
> able to assume it's a chunked-request-capable HTTP/1.1 server or proxy, and 
> if you don't, you time out, abort that connection (because you don't know if 
> it will interpret Transfer-Encoding), and try again with a non-chunked 
> request.
>
> Does that work in principle, disregarding broken implementations?
>
> Does it work in practice?

I think this is a case that would work if things worked the way we understand 
them and read the RFC, but in practise I believe the 100-continue support in 
the wild is not implemented this cleverly. I think a vast amount of 
100-continue responses are just not doing any checks at all but simply respond 
OK-continue without consideration. And then there's the opposite - servers 
that don't like 100-continue at all but would support a chunked-request.

I say "think" here because this is just my gut feeling, I haven't actually 
tested the theory.

-- 

  / daniel.haxx.se