Re: [Qemu-devel] [PATCH 01/11] QMP: Introduce specification file

[Daniel P. Berrange]

On Wed, Jun 24, 2009 at 12:55:37PM +0100, James wrote:
> > now providing there was a maintained library out there, would you use it ?
> > or do you have more concerns that were unanswered ?
> 
> I have exactly one concern. If Qemu grows an RPC protocol, it will be used 
> by a large number of other programs to control qemu. This is a good thing.
> But it is important that such a system 
> 
> 1) either supports some sort of introspection so that the functions and
>    their arguments can be divined by the external program without knowing
>    which particular version of qemu it is talking to.
> 
> 2) and/or supports an IDL so that the interface is properly documented in
>    something other than an under-edited text file.
> 
>       
> To this end I tentitatively suggest d-bus as a possible choice. It fills 1 
> and 2
> nicely and also allows each module to have its own interfaces and objects. 
> The IDL will also generate C bindings for both ends.

It depends what you mean by 'dbus' here. I don't think managing QEMU over
the dbus bus provides the right architecture - I don't think you want
every QEMU appearing on the bus.5B You could do direct peer-to-peer comms
so you're just using libdbus for message encapsulation / processing, but
there's not really much above XDR. XDR is nice because its a portable
library that works on any OS, including OS-X and WIndows, and solely
concerns itself with data encoding, not data transport.  

Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|