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Re: [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable desc
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response |
Date: |
Tue, 8 Dec 2009 12:25:13 +0000 |
User-agent: |
Mutt/1.4.1i |
On Tue, Dec 08, 2009 at 10:11:48AM -0200, Luiz Capitulino wrote:
> On Mon, 7 Dec 2009 21:37:16 +0100
> Markus Armbruster <address@hidden> 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.
I think it is fine to declare that 'desc' strings are subject to
arbitrary change. Even if QEMU includes this 'desc' I think in libvirt
will end up doing its own error code -> human string conversion,
simply because we need to translate the strings. So we'd only use
'desc' in any logging calls if it were present.
> 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.
Daniel
--
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- [Qemu-devel] [FOR 0.12 PATCH 00/18] QError conversions and more, Markus Armbruster, 2009/12/07
- [Qemu-devel] [FOR 0.12 PATCH 16/18] QError: New QERR_TOO_MANY_FILES, Markus Armbruster, 2009/12/07
- [Qemu-devel] [FOR 0.12 PATCH 08/18] QError: New QERR_INVALID_BLOCK_FORMAT, Markus Armbruster, 2009/12/07
- [Qemu-devel] [FOR 0.12 PATCH 12/18] QError: New QERR_FD_NOT_FOUND, Markus Armbruster, 2009/12/07
- [Qemu-devel] [FOR 0.12 PATCH 10/18] QError: New QERR_VNC_SERVER_FAILED, Markus Armbruster, 2009/12/07
- [Qemu-devel] [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response, Markus Armbruster, 2009/12/07
- [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response, Paolo Bonzini, 2009/12/08
- [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response, Markus Armbruster, 2009/12/08
- [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response, Markus Armbruster, 2009/12/08
- Re: [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response, Anthony Liguori, 2009/12/08
- Re: [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response, Luiz Capitulino, 2009/12/08
[Qemu-devel] [FOR 0.12 PATCH 04/18] QError: Put error definitions in alphabetical order, Markus Armbruster, 2009/12/07
[Qemu-devel] [FOR 0.12 PATCH 09/18] QError: New QERR_SET_PASSWD_FAILED, Markus Armbruster, 2009/12/07
[Qemu-devel] [FOR 0.12 PATCH 13/18] monitor: convert do_closefd() to QError, Markus Armbruster, 2009/12/07