Re: [Qemu-devel] [PATCH 19/22] qapi: add QMP put-event command

[Anthony Liguori]

On 03/10/2011 09:49 AM, Avi Kivity wrote:
> On 03/10/2011 05:41 PM, Anthony Liguori wrote:
> > > I also think it should be at the protocol layer:
> > >
> > > > { execute: some-command, id: foo, arguments: { ... } }
> > > < { result: { ... }, id: foo }
> > > > { subscribe: block-io-error, id: bar, arguments: { ... } }
> > > < { result: { ... } id: bar }
> > > < { event: block-io-error, id: bar, data : { ... } }
> > > > { unsubscribe: block-io-error, id: bar }
> > > < { result: { ... } id: bar }
> > >
> > > So events are now protocol-level pieces like commands, and the use 
> > > of tags is uniform.
> >
> >
> > Maybe for QMPv2, but for QMPv1, this is going to introduce an 
> > extremely incompatible change.
>
> Why?  It's 100% backwards compatible.

It's a very significant change for clients.  While technical compatible, 
it would require a change to the client infrastructure to support the 
new feature.

I'm not saying we shouldn't make a change like this, but we should 
minimize these type of changes.

Regards,

Anthony Liguori