On Mon, 25 Jan 2010 15:15:59 +0100 Markus Armbruster <arm...@redhat.com> wrote:
> Luiz Capitulino <lcapitul...@redhat.com> writes: > > > On Sun, 24 Jan 2010 18:35:14 +0000 > > Jamie Lokier <ja...@shareable.org> wrote: > > > >> Anthony Liguori wrote: > >> > >I'd like to be able to connect and be sure not to receive any async > >> > >messages, from simple scripts with simple output parsing. > >> > > >> > You can't have simple output parsing with QMP. You need a full JSON > >> > stack. The simplest script would be a python script that uses the > >> > builtin json support. Having async messages means that you'll have to > >> > loop on recv in order make sure that the response is a command response > >> > vs. an async message. It's just a few lines more of code so I have a > >> > hard time believing it's really a problem. > >> > > >> > But what you probably want is a python QMP library and that would mean > >> > you wouldn't need the few more lines of code. > >> > >> You're right. To be honest, parsing JSON can be done in a single Perl > >> regexp; a "full JSON stack" isn't much. > >> > >> On that note, it'd be good if the end of a QMP message is framed with > >> something that can't appear inside the JSON value, without having to > >> parse the JSON incrementally on each partial read(). There are plenty > >> of short character sequences to choose from that can't appear. Some > >> JSON parsers expect a whole well-formed expression or throw a parse > >> error - it's what people do over HTTP after all. So you wait until > >> you think you've read a whole one, then pass it to the JSON parser. > > > > The Monitor sends a CRLF sequence at the end of each line and I have > > maintained that behaivor for QMP, but it's hard to _guarantee_ that this > > sequence won't appear inside a json-string. > > JSON requires control characters in strings to be escaped. RFC 4627 > section 2.5: Excellent. > > In practice it doesn't, afaik. > > If it doesn't, then it's not proper JSON, is it? My 'doesn\'t' meant: no JSON string we currently generate has CR or LF in them, as far as I can remember. But even if it happens it's not a problem, as you clarified.
