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Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support |
Date: |
Mon, 25 Jan 2010 15:15:59 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
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:
A string begins and ends with quotation marks. All Unicode
characters may be placed within the quotation marks except for the
characters that must be escaped: quotation mark, reverse solidus, and
the control characters (U+0000 through U+001F).
> In practice it doesn't, afaik.
If it doesn't, then it's not proper JSON, is it?
- 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, Luiz Capitulino, 2010/01/22
- Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support, Anthony Liguori, 2010/01/22
- 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, Avi Kivity, 2010/01/25
- 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, 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 <=
- 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, 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