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Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support |
Date: |
Mon, 25 Jan 2010 12:22:58 -0200 |
On Mon, 25 Jan 2010 15:15:59 +0100
Markus Armbruster <address@hidden> wrote:
> Luiz Capitulino <address@hidden> writes:
>
> > On Sun, 24 Jan 2010 18:35:14 +0000
> > Jamie Lokier <address@hidden> 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.
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, (continued)
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Avi Kivity, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Jamie Lokier, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Anthony Liguori, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Jamie Lokier, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Luiz Capitulino, 2010/01/25
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Markus Armbruster, 2010/01/25
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support,
Luiz Capitulino <=
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Anthony Liguori, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Avi Kivity, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Anthony Liguori, 2010/01/24
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Luiz Capitulino, 2010/01/25
[Qemu-devel] Re: [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Avi Kivity, 2010/01/24
[Qemu-devel] [PATCH 09/11] Monitor: Introduce find_info_cmd(), Luiz Capitulino, 2010/01/21
[Qemu-devel] [PATCH 10/11] QError: New QERR_QMP_INVALID_MODE_COMMAND, Luiz Capitulino, 2010/01/21
[Qemu-devel] [PATCH 11/11] QMP: Enable feature negotiation support, Luiz Capitulino, 2010/01/21
Re: [Qemu-devel] [RFC 00/11]: QMP feature negotiation support, Markus Armbruster, 2010/01/22