It's not on our roadmap for ROS 1.4:

http://www.ros.org/reps/rep-0101.html

For rospy, I was waiting until I redesigned the inner i/o engine. I
won't speak for roscpp.

best,
Ken

2010/10/5 Stéphane Magnenat <stephane.magnenat@mavt.ethz.ch>:
> 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
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