Re: [Qemu-devel] ANN: QEMU Monitor Protocol git tree

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Sep 22, 2009 at 08:56:04PM -0500, Anthony Liguori wrote:
> Luiz Capitulino wrote:
> >Now the controversial part: it's json based. ;)
> >
> >I have chosen json because of the reasons already explained by others in
> >the original QMP thread. Basically, json is so simple that if we design
> >a small protocol from scratch, chances are it will look like json.
> >  
> 
> json is not a deal break.  My main concern was our ability to extend 
> json and whether supporting stock json libraries was a hard 
> requirement.  I also would like to see a C client library since our 
> biggest consumer (libvirt) is based in C.

I've googled around quickly and there are at least 5 pieces of C code
and/or C libraries that can parse JSON. Hopefully one of them will be
sufficient / suitable for libvirt's needs. We'll just need to try it
out and see what happens....

> >2.1 General Definitions
> >-----------------------
> >
> >All interactions transmitted by Client and Server are json-objects that end
> >with CRLF.
> >  
> 
> CRLF?  Really?
> 
> Ignoring the dos-ism, since you can parse JSON with a regexp, why do we 
> need explicit message boundaries?

I think it would be nice to be able to assume that each JSON message 
will not cross a line-end boundary. Whether we use CRLF, just CR or
just LF I don't mind. Its much easier to search for a message boundary
by just doing strchr('\n')  than having to actually parse the JSON or
use a regexp at that point.

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 :|