[ros-users] re-subscription

Tully Foote tfoote at willowgarage.com
Thu Mar 4 16:34:12 UTC 2010

Are you starting your roscore seperately and is it staying up when you
restart your publisher?

This is on speculation, but the symptoms are consistent.  If you are
starting your publisher first with roslaunch it will automatically launch
roscore.  However when you take down that first roslaunch the roscore will
come down with it.  This will orphan any running nodes, and they will not
work properly once they have lost contact with the master.  If you are
relying on roslaunch to start the roscore for you, I would suggest manually
starting it separately so that you can make sure it stays up when you
restart other nodes.


On Thu, Mar 4, 2010 at 7:51 AM, Brian Gerkey <gerkey at willowgarage.com>wrote:

> On Thu, Mar 4, 2010 at 3:51 AM, Klaus Petersen
> <klaus at takanishi.mech.waseda.ac.jp> wrote:
> > I have a very basic problem: First, I establish a connection between a
> > publisher node and a subscriber node. At this point I can receive
> > messages from the publisher with the subscriber node. But when I
> > re-start my publisher node (quit and run again) the subscriber does not
> > automatically resubscribe to the message. I have to restart the
> > subscriber as well to be able to receive again. Is this the normal
> > behavior with ros or am I doing something wrong? I have quite a big
> > robot control program tied to one of the nodes, so restarting along the
> > way (the initialization of the robot takes ages) is very troublesome.
> hi Klaus,
> Something's going wrong there.  When your publisher is restarted, it
> should re-advertise with the master, which should send the new
> publisher list to your subscriber, which should then re-connect to
> your publisher.
> You can test this behavior with roscpp_tutorials/talker and
> roscpp_tutorials/listener; no matter in what order they're
> (re)started, listener will always connect to talker.
> Can you tell us something about your publisher and subscriber? Is
> there anything unusual about your subscriber?
>        brian.
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Tully Foote
Systems Engineer
Willow Garage, Inc.
tfoote at willowgarage.com
(650) 475-2827
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