Subject: Re: Request for detailed documentation of git pack protocol

From: Jakub Narebski <[email-masked]>
Date: Thu, 4 Jun 2009 00:04:09 +0200

On Wed, 3 Jun 2009, Shawn O. Pearce wrote:
> Jakub Narebski <[email-masked]> wrote:

> > BTW. do "include-tag" capability MUST NOT (REQUIRED) be send if there
> > are not tags (tag objects?), or just SHOULD NOT (RECOMMENDED), or even
> > MAY NOT (OPTIONAL).  GitHub server doesn't send it if there are no 
> > tags...
> 
> Clients MAY always send include-tag, hardcoding it into a request.
> The decision for a client to request include-tag only has to do
> with the client's desires for tag data, whether or not a server
> had advertised objects in the refs/tags/* namespace.
> 
> Clients SHOULD NOT send include-tag if remote.name.tagopt was set
> to --no-tags, as the client doesn't want tag data.
> 
> Servers MUST accept include-tag without error or warning, even if the
> server does not understand or support the option.
> 
> Servers SHOULD pack the tags if their referrant is packed and the
> client has requested include-tag.
> 
> Clients MUST be prepared for the case where a server has ignored
> include-tag and has not actually sent tags in the pack.  In such
> cases the client SHOULD issue a subsequent fetch to acquire the
> tags that include-tag would have otherwise given the client.

So do I understand correctly that capabilities are governed by the
following generic rules:

1. Server sends space separated list of capabilities it support. It
   MUST NOT send capabilities it *does not* support. It MAY NOT send
   "include-tag" if there are no tag objects (or is it SHOULD NOT?).
2. Client sends space separated list of capabilities it wants. It SHOULD
   (or perhaps it is MAY?) send subset of server capabilities, i.e do
   not send capabilities served does not advertise.
3. Server MUST ignore capabilities it does not understand. Server MUST
   NOT ignore capabilities (or SHOULD NOT only?) that client requested
   and server advertised.

I know that client MUST send only maximum of one of "side-band" and 
"side-band-64k", but how should server reacts if client sends both?
Should it use "side-band-64k"?

-- 
Jakub Narebski
Poland