From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NHyvD-0005d1-WB for qemu-devel@nongnu.org; Tue, 08 Dec 2009 07:12:04 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NHyv8-0005bR-Ib for qemu-devel@nongnu.org; Tue, 08 Dec 2009 07:12:02 -0500 Received: from [199.232.76.173] (port=44188 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NHyv7-0005bJ-P1 for qemu-devel@nongnu.org; Tue, 08 Dec 2009 07:11:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51070) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NHyv7-00081M-6i for qemu-devel@nongnu.org; Tue, 08 Dec 2009 07:11:57 -0500 Date: Tue, 8 Dec 2009 10:11:48 -0200 From: Luiz Capitulino Message-ID: <20091208101148.119bed20@doriath> In-Reply-To: <1260218236-22143-19-git-send-email-armbru@redhat.com> References: <1260218236-22143-1-git-send-email-armbru@redhat.com> <1260218236-22143-19-git-send-email-armbru@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org On Mon, 7 Dec 2009 21:37:16 +0100 Markus Armbruster wrote: > -{ "error": { "class": json-string, "data": json-value }, "id": json-value } > +{ "error": { "class": json-string, "data": json-value, "desc": json-string }, > + "id": json-value } > > Where, > > - The "class" member contains the error class name (eg. "ServiceUnavailable") > - The "data" member contains specific error data and is defined in a > per-command basis, it will be an empty json-object if the error has no data > +- The "desc" member is a human-readable error message. Clients should > + not attempt to parse this message. > - The "id" member contains the transaction identification associated with > the command execution (if issued by the Client) As we've talked on irc, I don't agree with this change. Basically, adding 'desc' to the standard error message introduces all the problems we've discussed about free-form English strings. I feel that QError is becoming the worst of all proposals. I agree with you that it's not as easy as it should be to report errors, but as we're targeting on Clients I was convinced that we could not have the best API internally but offer a good interface for Clients. Now, having 'desc' as part of the standard protocol is like not having the best API internally and offering a bad interface for Clients. Not to mention that those strings can't be modified when the protocol becomes stable and we're probably talking about dozens if not a hundred of strings. Ok, there isn't a reason to change them often, but it's still one more thing to maintain. Having said that, I would agree to have 'desc' as part of debug information. I have patches in my tree which adds CONFIG_DEBUG_QMP, if one enables it information about the error location will also be part of the error message. I would agree having 'desc' there too.