Re: [Bug-wget] [GSoC 2015] Basic HTTP/2 support

[Daniel Stenberg]

On Thu, 30 Apr 2015, Miquel Llobet wrote:

> > I'm glad to see this project come to life, and I'm happy to see you chosing 
> > to base it on Tatsuhiro's awesome nghttp2 library. We do this in the curl 
> > project too.
>
> I blame Giuseppe for suggesting it :-), and nghttp2 looks really good, can't 
> wait to dive into it this summer! What challenges did you face when 
> implementing HTTP/2 in curl? I would love to hear about that.

It's been a long journey for us that began long before the protocol settled, 
and nghttp2 has also been a moving target along the way. So I'm not sure what 
good lessons i have from this that are actually transferable to your project.

Some quick things I came to think about:

HTTP/2 over plain text is annoying with the Upgrade: and wasted RTT, it is 
much easier and simpler over HTTPS and ALPN.

The fact that OpenSSL doesn't support ALPN until 1.0.2 is also annoying since 
it is still not present in lots of distros. ALPN is however getting 
implemented in many TLS libraries now so things are looking good.

You should probably consider to make a translation layer from HTTP/2 headers 
to HTTP/1 and back, so that all the header parsing and request generation etc 
can remain pretty much as-is. That's what we do in curl and that's how Firefox 
does it internally.

--

 / daniel.haxx.se