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Date: Wed, 24 Jun 2009 15:56:46 +0100
From: Chris Webb <chris.webb@elastichosts.com>
Subject: Re: [Qemu-devel] [PATCH 01/11] QMP: Introduce specification file
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: ehabkost@redhat.com, jan.kiszka@siemens.com, dlaor@redhat.com, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, Avi Kivity <avi@redhat.com>, Vincent Hanquez <tab@snarc.org>

Anthony Liguori <anthony@codemonkey.ws> writes:

> There are two questions to resolve.  The first is whether we should  
> continue with the current direction (line-based protocol) or whether we  
> should switch to an RPC.  The second question is which RPC we should use.
>
> I'm not at all convinced that we should switch to an RPC mechanism in  
> the first place.  Perhaps someone could summarize the advantages of  
> doing this because right now, I don't see many.
>
> With respect to RPC choice, if we did go that route, I'd be very  
> concerned about using jsonrpc verses a more well established rpc.  I  
> would honestly prefer xml-rpc over jsonrpc.

We are an example of a end user of qemu (or more specifically qemu-kvm) that
doesn't go via a management layer like libvirt. Our management shell scripts
directly control the virtual machines using the current line-oriented 'human
friendly' monitor. This is a bit of a pain, but not too bad in practice.

A more regular and well defined line-based protocol would be a big plus for
us, whereas something like jsonrpc or xml-rpc would be a complete disaster
to call from the shell---less useful than the current human oriented monitor
rather than more so.

(Aside from the practical question, personally I share your gut feeling that
it seems like a sledgehammer to crack a nut and not a good fit at all for
this layer of the stack.)

Cheers,

Chris.