[ros-users] re-subscription

Klaus Petersen klaus at takanishi.mech.waseda.ac.jp
Fri Mar 5 01:41:05 UTC 2010

Hi Tully,

Thanks for the suggestions. I am starting roscore separately and it 
keeps running when I restart the publisher. Indeed it seems like there 
is something wrong with the communication to the master node for 
re-publishing. I hear the sound of the network blues..


Tully Foote さんは書きました:
> Klaus,
> 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. 
> Tully
> On Thu, Mar 4, 2010 at 7:51 AM, Brian Gerkey <gerkey at willowgarage.com 
> <mailto:gerkey at willowgarage.com>> wrote:
>     On Thu, Mar 4, 2010 at 3:51 AM, Klaus Petersen
>     <klaus at takanishi.mech.waseda.ac.jp
>     <mailto: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 <mailto:tfoote at willowgarage.com>
> (650) 475-2827
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