[ros-users] actionlib design questions

[Herman Bruyninckx]

On Wed, 15 Sep 2010, Tully Foote wrote:

> SMACH is the recommended way to coordinate complex systems.  actions using
> actionlib are commonly used as states within SMACH.
> actions are as you say very similar to services in their use but have more
> control and feedback.  SMACH is designed to work as a coordination engine,
> strongly based on a state machine.  SMACH has been designed that it is
> trivial to use an action as a state within a SMACH state machine.  Thus we
> use SMACH and actionlib at the same time.  

So why are they implemented in two separate code trees? Why do they not
share everything they could share? (Which is a lot, because coordination
with state machines _is_ coordination with state machines, whether inside
or outside of a certain context...) Legacy? Developer communication short
circuits? Bouncing egos? Not Invented Here Syndrome? :-)))

I'm joking of course, but I do wonder what the real differences are, since
I do not see the case for two fully separated libraries...

> Tully

Herman

> 
> On Wed, Sep 15, 2010 at 5:52 AM, Enea Scioni <enea.scioni at student.unife.it>
> wrote:
>
>       HI all,
>
>       I'm following this topic but I'm also a bit confused..
>       In order to manage the whole system, composed as hundreds nodes,
>       should I
>       use SMACH (instead actionlib)?
>       What is the " best practice " that ROS suggest? When should I
>       use actionlib
>       and when SMACH?
>
>       Starting from the documentation (and my experiments), in a
>       nutshell I see
>       actionlib more similar to a ROS Service, but with added
>       features, as
>       possibilities to receive a feedback, delete the request and so
>       on; to do
>       that actionlib use/implement an "internal" state machine in
>       order to manage
>       the communication protocol on topic between the Action Server
>       and Action
>       Client.
>       Is it true or I'm making a mistake?
>
>       Regards,
>       Enea Scioni
>       --
>       View this message in context:http://ros-users.122217.n3.nabble.com/actionlib-design-questions-tp1468507p
>       1479561.html
>       Sent from the ROS-Users mailing list archive at Nabble.com.
> _______________________________________________
> ros-users mailing list
> ros-users at code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
> 
> 
> 
> 
> --
> Tully Foote
> Systems Engineer
> Willow Garage, Inc.
> tfoote at willowgarage.com
> (650) 475-2827
> 
>

--
   K.U.Leuven, Mechanical Eng., Mechatronics & Robotics Research Group
     <http://people.mech.kuleuven.be/~bruyninc> Tel: +32 16 328056
   EURON Coordinator (European Robotics Research Network) <http://www.euron.org>
   Open Realtime Control Services <http://www.orocos.org>
   Associate Editor JOSER <http://www.joser.org>, IJRR <http://www.ijrr.org>