[lttng-dev] RFC LTTng session and daemon configuration save and restore

[Jérémie Galarneau]

On Thu, Dec 5, 2013 at 12:38 PM, Stefan Seefeld
<stefan_seefeld at mentor.com> wrote:
> Hi Jérémie,
>
>
>
> On 12/04/2013 04:33 PM, Jérémie Galarneau wrote:
>> RFC - LTTng session and daemon configuration save and restore
>
> I think this is a great idea.
>
>
>> Session Configuration File Format
>> ---------------------------------
>>
>> Finally, it seems that using a standard hierarchical format such as JSON or
>> XML would be the most appropriate choice. Both of these formats have intrinsic
>> support for representation of hierarchical relationships. They also benefit from
>> having a lot of hardened external libraries that will provide parsing,
>> validation and write support.
>
> I fully agree that re-inventing another language (which includes both
> syntax and semantics !) is not an easy task, and should be avoided for
> lots of reasons. In fact, I would also avoid XML for that same reason,
> as it's not really a language in itself, rather than a baseline on top
> of which a language may be defined.

I don't see an XML schema as something as demanding as defining a new
language. One of the reasons why I prefer XML here is that the schema
really makes it easy to validate the files and integrate with existing
tools.

>
> There are a few existing proven solutions that are widely used in many
> different domains, all involving scripting languages that can easily be
> layered on top of C/C++ APIs. Two of the most commonly used are Python
> and Lua, which would allow you to write configuration files as Python /
> Lua scripts.
>
> Have you considered those ?

Not really. I guess it makes sense to have these script-config files
when your application is written in that language, but I'm not sure I
see the benefit here.

Furthermore, I think the integration of a LUA/Python interpreter in
lttng-tools would not go down well.

Thanks,
Jérémie

>
> Regards,
>         Stefan
>
> --
> Stefan Seefeld
> CodeSourcery / Mentor Graphics
> http://www.mentor.com/embedded-software/
>
>
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-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com