[ltt-dev] UST socket protocol

[Pierre-Marc Fournier]

On 09/07/2010 02:30 AM, Nils Carlson wrote:
> I've been looking through the socket protocol for UST and am a bit
> curious about the construction of it. Is there a reason we haven't just
> defined a ustctl package type with a command field, a result field and a
> data field?
>

Not sure I understand.

There is the socket protocol and there is the ustcmd API. The ustcmd API 
is there to make it easy to control tracing in a system from within a C 
program like TCF or ustctl. It in turn converts the commands it receives 
to the text-based ust socket protocol which libust (inside the traced 
app) is able to parse.

If I understand your question, you are asking why ustctl is not talking 
directly the socket protocol. The answer to that is that it used to do 
this. But the ustcmd api had to be introduced in order to allow other 
programs like TCF to control the tracing. The lttng TCF agent currently 
does this and depends on libustcmd.

pmf