Re: [Qemu-devel] [PATCH 0/6]: QMP: Fix issues in parser/lexer

[Avi Kivity <avi@redhat.com>]

On 05/20/2010 12:43 AM, Anthony Liguori wrote:
>
> The JSON specification explicitly says:
>
> "A JSON parser transforms a JSON text into another representation. A 
> JSON parser MUST accept all texts that conform to the JSON grammar.  A 
> JSON parser MAY accept non-JSON forms or extensions."
>
> IOW, we're under no obligation to reject extensions and I can't think 
> of a reason why we should.

At the very least, we should document them.  If the extension doesn't 
add any value but is merely a side effect of the implementation, we 
should remove it.

Examples where this could hurt us:

- we move to a json parsing library, the extension disappears, client breaks
- someone writes a qemu simulator to test managment tool scalability 
(run zillions of fake guests on one machine), client breaks
- someone writes a debug tool that interposes between client and qemu, 
client breaks
- the json specification adds a new form that conflicts with one of our 
extensions [1], we can't use the new form

Being strict in what we accept will reduce our support burden later on.

[1] allowing infinite extensibility like this is irresponsible

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.