[lttng-dev] Human read-writeable format for CTF traces

[Mathieu Desnoyers]

----- Original Message -----
> From: "Michel Dagenais" <michel.dagenais at polymtl.ca>
> To: "Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>
> Cc: lttng-dev at lists.lttng.org, "Geneviève Bastien" <gbastien+lttng at versatic.net>
> Sent: Monday, February 3, 2014 11:00:17 AM
> Subject: Re: [lttng-dev] Human read-writeable format for CTF traces
> 
> 
> > I would expect that the ctf writer API recently added to babeltrace
> > (currently in master branch), along with the Python bindings that cover
> > trace read and write APIs, should allow you to implement things like:
> > 
> > - A plugin to read a CTF trace, and output it in an intermediate format
> >   to facilitate edits (e.g. XML as you propose),
> > - A plugin to read this XML format and output a CTF trace.
> 
> Yes, this would indeed be extremely helpful, in XML and/or JSON.
> 
> > You could also generate the XML trace completely by hand if you like, and
> > then convert it to CTF with the second plugin I'm relating to above.
> 
> The likely scenario is to add a few events by hand.
> 
> > Another possibility is that the XML description also allows
> > describing what the trace contains at a slightly higher level. For
> > instance, if you
> > have a periodic event happening for a certain amount of time, it would
> > be described in XML, and then "generated" by the XML-to-CTF
> > converter.
> 
> Do we want to describe this in XML or in Python? We could have "CTF" to
> "Python statements" generating XML. Then we could add loops by hand. We
> could also have CTF to XML, with hooks to merge Python generated events.

I very much like this idea. Indeed, with a CTF-to-Python-statements converter,
we can easily tweak the resulting python script to add events, modify events,
and even use loops and re-use functions. This would be extremely useful for
unit-testing the state system, and would allow re-use (import) of patterns
more easily than with XML descriptions.

Thanks,

Mathieu

> 
> In addition, TMF may also want to offer similar functionality, an XML dump of
> events and an XML events reader. Indeed, TMF supports a few formats other
> than CTF.
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com