Re: [Qemu-devel] Re: [FOR 0.12 PATCH 18/18] QMP: add human-readable description to error response

[Luiz Capitulino]

On Tue, 08 Dec 2009 07:18:11 -0600
Anthony Liguori <address@hidden> wrote:

> 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.
> >   
> 
> It's not free form English.  The 'desc' string is always autogenerated 
> based on the error object.
> 
> It's completely redundant information because you can already generate 
> that string, but it simplifies client creation because a lazy client 
> does not have to include the conversion table if they only care about 
> English error output.

 I wonder if we could have a simpler design for the internal API if
we knew in advance that 'desc' would be part of the standard
error message, eg. error code based.

 But, as Markus said it's not the 'worst' as I've put it, let's
move forward then.