[ros-users] Can service answers be asynchronous?

[Stéphane Magnenat]

Hello,

I am about to start writing a bridge between ROS and ASEBA [1]. In this 
context, ASEBA is a low-level (cross-microcontroller) middleware, whose 
features I would like to expose to ROS. I already did this with D-Bus [2].

As ASEBA talks to microcontrollers, there might be delays in answers, so 
when an RPC-like query is performed on the Service, I would like the 
function to return to the event loop and to be able to provide an answer 
to the RPC later, when the data from the microcontroller will  have 
arrived. As far as I understand, as ROS is message-based, this should be 
possible. D-Bus provides an API for this [3]. I have not found any 
information related to asynchronous answers in the context of ROS, and 
if I have read the API doc correctly, ROS does not provide such a 
feature in its service API. Is it correct? If so, do you plan to 
implement this at some point?

Thank you, kind regards,

Stéphane


[1] http://mobots.epfl.ch/aseba.html
[2] http://svn.gna.org/viewcvs/aseba/trunk/medulla/
[3] for instance, with QtDBus, see:
     http://doc.trolltech.com/latest/qdbusmessage.html#setDelayedReply

-- 
Dr Stéphane Magnenat
http://stephane.magnenat.net