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

[Avi Kivity]

On 06/23/2009 07:09 PM, Anthony Liguori wrote:
> Avi Kivity wrote:
> > > I'd rather not do json.
> >
> > Why not?
>
> Because it's too much complexity at this level in the stack.

I don't see that.  Just another library.

> > > As they stand, I think the current patch set is very close to being 
> > > mergable.  I'd rather not go off on a new tangent.
> >
> > It fulfils all are requirements and more.  There's a C implementation 
> > available.  We can concentrate on the commands and ignore the plumbing.
>
> The same is true for XML-RPC, CIM, dbus, etc.  RPC grow like weeds.  
> In 5 years, it will be shocking that qemu uses jsonrpc instead of the 
> next super-neat RPC protocol.

The only one that actually competes here is xml-rpc, which is 
ridiculously verbose.

> If we did a real RPC mechanism, I'd want to stick with something 
> tried-and-true like XDR.

Having some experience with xdr, I'd call it tried-and-wrong.  It's 
simply horrible.

>   But an RPC mechanism is not the monitor.  If we were going to do 
> that, there's no point in morphing the monitor into that.
>
> What we're doing here is adding a computer-mode to the existing 
> monitor.  This will be easy for current apps to consume and for us to 
> transition the code base to.  It's a safe and incremental improvement.

An RPC makes it a lot easier for clients to parse, there's no need for a 
regular expression per command, or to bother with line continuations 
etc.  You just focus on the data.

We have an opportunity to make a clean break, let's make use of it.

> I don't want to invent Xen-API here and go through that pain in QEMU.

I don't see the parallel.

--
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