From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NZPqb-0005lG-Nd for qemu-devel@nongnu.org; Mon, 25 Jan 2010 09:23:21 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NZPqX-0005ja-8A for qemu-devel@nongnu.org; Mon, 25 Jan 2010 09:23:21 -0500 Received: from [199.232.76.173] (port=36193 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NZPqW-0005jQ-PT for qemu-devel@nongnu.org; Mon, 25 Jan 2010 09:23:16 -0500 Received: from mx20.gnu.org ([199.232.41.8]:64593) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NZPqV-0008Em-PZ for qemu-devel@nongnu.org; Mon, 25 Jan 2010 09:23:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NZPqP-0003Iw-Do for qemu-devel@nongnu.org; Mon, 25 Jan 2010 09:23:09 -0500 Date: Mon, 25 Jan 2010 12:22:58 -0200 From: Luiz Capitulino Subject: Re: [Qemu-devel] [PATCH 08/11] QMP: Asynchronous messages enable/disable support Message-ID: <20100125122258.22b2a56b@doriath> In-Reply-To: References: <1264108180-3666-1-git-send-email-lcapitulino@redhat.com> <1264108180-3666-9-git-send-email-lcapitulino@redhat.com> <4B59E8DF.5020001@codemonkey.ws> <4B5C2251.7050509@redhat.com> <20100124110725.GA5668@shareable.org> <4B5C68D6.6090502@codemonkey.ws> <20100124183514.GA14840@shareable.org> <20100125094916.5d493493@doriath> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: qemu-devel@nongnu.org, Avi Kivity On Mon, 25 Jan 2010 15:15:59 +0100 Markus Armbruster wrote: > Luiz Capitulino writes: > > > On Sun, 24 Jan 2010 18:35:14 +0000 > > Jamie Lokier 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.