Request for detailed documentation of git pack protocol

[Jakub Narebski <jnareb@gmail.com>]

We have now proliferation of different (re)implementations of git:
JGit in Java, Dulwich in Python, Grit in Ruby; and there are other
planned: git# / managed git in C# (GSoC Mono project), ObjectiveGit
in Objective-C (for iPhone IIRC).  At some time they would reach
the point (or reached it already) of implementing git-daemon...
but currently the documentation of git protocol is lacking.

This can lead, as you can read from recent post on git mailing, to
implementing details wrong (like Dulwich not using full SHA-1 where
it should, leading to ordinary git clients to failing to fetch from it),
or fail at best practices of implementation (like JGit last issue with
deadlocking for multi_ack extension).

The current documentation of git protocol is very sparse; the docs
in Documentation/technical/pack-protocol.txt offer only a sketch of
exchange.  You can find more, including pkt-line format, a way sideband
is multiplexed, and how capabilities are negotiated between server and
client in design document for "smart" HTTP server, for example in
  Subject: Re: More on git over HTTP POST
  Message-ID: <20080803025602.GB27465@spearce.org>
  URL: http://thread.gmane.org/gmane.comp.version-control.git/91104/focus=91196

It would be really nice, I think, to have RFC for git pack protocol.
And it would help avoid incompatibilities between different clients
and servers.  If the document would contain expected behaviour of
client and server and Best Current Practices it would help avoid
pitfals when implementing git-daemon in other implementation.

Perhaps in the future it could be sent for inclusion as "official"
RFC to IETF?  (Dreaming big).


Unfortunately I don't know enough about this area of code to write
one myself.

-- 
Jakub Narebski
ShadeHawk or jnareb on #git
Poland