Re: [Libvir] RFC [0/3]: Re-factor QEMU daemon protocol to use XDR

[Mark McLoughlin <markmc redhat com>]

Hi Dan,
	Only getting around to looking at this now ...

	This all looks perfectly reasonable to me. I don't see a good reason
why you shouldn't just go ahead with this next time we feel like
de-stabilising the tree for a while.

	The only downside is things might break a little for people during
upgrades.

	One comment ...

On Thu, 2007-03-22 at 20:46 +0000, Daniel P. Berrange wrote:

>   1. Add an extra initial message type to do a major/minor version number
>      exchange. Based on the negotiated versions, the server can activate
>      or deactivate particular requests it allows from the client.

	I think the approach I'd take would be:

  - Never remove a request from the server

  - Allow the server to tell the client the latest version of the 
    protocol it supports

  - The client, where it can, falls back to an older request if the 
    client doesn't support the appropriate newer request. Otherwise,
    it returns an error to the caller.

	The way a newer client has a chance of dealing with an older server and
an older client client works with a newer server.

Cheers,
Mark.