Re: [Qemu-devel] Re: [libvirt] Supporting hypervisor specific APIs in libvirt

From: "Daniel P. Berrange" <berrange@redhat.com>
To: Vincent Hanquez <tab@snarc.org>
Cc: "libvir-list@redhat.com" <libvir-list@redhat.com>,
	qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>,
	Paul Brook <paul@codesourcery.com>, Avi Kivity <avi@redhat.com>
Subject: Re: [Qemu-devel] Re: [libvirt] Supporting hypervisor specific APIs in libvirt
Date: Thu, 25 Mar 2010 15:07:20 +0000	[thread overview]
Message-ID: <20100325150720.GH10705@redhat.com> (raw)
In-Reply-To: <20100325145652.GA25506@snarc.org>

On Thu, Mar 25, 2010 at 02:56:52PM +0000, Vincent Hanquez wrote:
> On Thu, Mar 25, 2010 at 01:59:22PM +0000, Daniel P. Berrange wrote:
> > > From my point of view, i wouldn't want to write a high level management 
> > > toolstack in C, specially
> > > since the API is well defined JSON which is easily available in all high 
> > > level language out there.
> > 
> > It was pretty straightforward for libvirt to talk to the JSON protocol
> > from C using the YAJL  library, so I don't think it is all that much of 
> > a barrier for low level languages like C either.
> 
> note, that it's not the talking JSON part that's difficult to do in C (it's
> just midly annoying compare to a highlevel language), but all the other part of
> a toolstack. Since there's no performance requirements, writing in C is just a
> bit of a waste ot time, but that's up to the developpers to choose the tools he
> wants, even if it's not the most appropriate one ;)
> 
> > If we want to make life easy for app/library developers working against QEMU,
> > then the far more important aspect is to guarentee stability of all the QEMU
> > interfaces since that is where all the serious pain occurs over time.
> 
> if you're talking about the QMP interface then I agree with you. This need to
> be back/forward compatible as much as possible and stable.
> 
> the other interface (i.e. the user monitor) has no business beeing
> backward-compatible though, since it should never be used to talk a RPC.

I agree apps shouldn't use it for RPC, but admins using the interactive user 
monitor are just as deserving of stable commands & args. 

Daniel
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