Subject: Would a header/schema compiler help?

From: Phillip Hallam-Baker <[email-masked]>
Date: Tue, 17 Jul 2012 10:09:56 -0400

One of the design choices I find a little troubling in SPDY is the use
of header compression over a compact representation.

Compression algorithms worry me because the only way I can implement
them is to call someone's library. I can write my own code to
implement RFC822 header parsing. In fact I have done so a dozen times
at least.

ASN.1 and XML schemas are undoubtedly how to do a protocol 'right' in
the academic sense of get some good abstractions in there. But they
both come with hideous baggage. ASN.1 started too large and has been
tweaked endlessly until it became nonsense. XML encoding is bloated
and XML Schema drags in the whole SGML legacy that the WG was meant to
chuck in the dustbin. I dare you to use a model group in your next XML
spec.

But JSON proves that it does not have to be that way. Over the past
couple of months I have put together what amounts to a schema compiler
for JSON. I am currently working on putting the compiler and the tools
used to build it out on Github under an open source license.

Unlike your regular schema compiler, this one makes it easy to
retarget the code generation at a different language. Writing a JSON
back end for C# took me about a week (and I was developing the tool at
the same time). I could modify that code to generate C in a day. Want
python, perl, Java, no problem.

The JSON protocol synthesizer is built using the Goedel
meta-synthesizer (which is of course written in itself). Comodo owns
the protocol synth, I own the meta-synth. They should both be up on
github under an MIT license in a few weeks.

It seems to me that it would be useful to have a compiler for RFC822
style headers. The basic strategy being similar to a 'jack up' house
renovation. First we jack up the level of abstraction in the HTTP spec
by defining the headers in terms of a schema that is designed for that
specific purpose. Then we build in the new ground floor (aka encoding)
underneath it.

-- 
Website: http://hallambaker.com/