Re: How can i write a new protocol for git

["Shawn O. Pearce" <spearce@spearce.org>]

Mike Hommey <mh@glandium.org> wrote:
> On Fri, Sep 05, 2008 at 05:22:57PM +0800, Sky Patrick wrote:
> > 
> > If i want to write a new protocol for file transfer and would like to
> > to integrate it with git. Is it possible and easy to integrate it ?
> > Currently, i know that jgit may achieve it, but it is a Java
> > implementation and may not work with git command line program that
> > written in C.

Writing a dumb protocol support isn't difficult in JGit due to the
abstractions in place.  Its a little harder in C Git, unless Mike
(or someone else) can abstract out the cURL library usage and make
it more flexible.  Though these days cURL supports just about any
file transfer protocol known.
 
> First, it would depend if you need this new protocol to be a dumb
> protocol (like rsync and http) or "native" (git or ssh).

Writing a smart protocol is a PITA.  Look at the smart HTTP effort
I am trying to do.  OK, I'm not spending a whole lot of time on
it, but its a damn difficult thing to do well, and to keep simple
enough that it can be described and reimplemented.  Otherwise we
have another that-thing-before-Git on our hands.

> I've been meaning to refactor the dumb protocol "stack" for a while, but
> haven't gone much further than ideas in my mind (i.e. no code). I also
> have some start of http code recfactoring, that is waiting for this dumb
> protocol rework to be completed.

Yea.  One reason why I'm doing the smart HTTP effort prototype in
JGit is because the C code structure makes this harder to implement
without first going through a number of refactorings.  Though for the
smart HTTP stuff I really need to refactor fetch-pack/send-pack and
upload-pack/receive-pack, not the dumb walkers.

-- 
Shawn.