[ros-users] Publish/Subscriber loosing first message

[Sebastian Schneider]

Thank you for the link to the ticket. According to the third comment the 
behaviour seems to be expected, or better said: One should not rely on a 
"one-shot" publisher to work.

But read for yourself:
https://code.ros.org/trac/ros/ticket/3450#comment:3

Personally, I agree, that in a publish/subscriber communication one can 
never guarantee that each subscriber will get each message. Since one 
never nows how many subscribers are listening this would be a hard job 
anyway. But, if the circumstances are that the subscriber is already 
listening and there are no connection problems (e.g. both parties 
running on the same host) then I don't see why a published message 
should not be received by the subscriber.

Sebastian



Am 11.05.2011 12:19, schrieb Ugo Cupcic:
> Hi,
>
> You can have a look at this:
> https://code.ros.org/trac/ros/ticket/3450#comment:2
>
> <https://code.ros.org/trac/ros/ticket/3450#comment:2>Could you ask the
> question again on ros-answer? This way we can put this answer here.
>
> Cheers,
>
> Ugo
>
> On Wed, May 11, 2011 at 11:14 AM, Sebastian Schneider
> <s.schneider at unibw.de <mailto:s.schneider at unibw.de>> wrote:
>
>     Hello,
>
>     I'm currently trying out the Tutorials from the ROS Wiki and I have a
>     question to the part "Examining the Simple Publisher and Subscriber"
>     (http://www.ros.org/wiki/ROS/Tutorials/ExaminingPublisherSubscriber). So
>     far, my programs are working as expected, but I wonder why the first
>     message from the publisher "Hello there! This is message [0]" does not
>     reach the subscriber. The first message the subscriber receives is
>     "Hello there! This is message [1]".
>
>     This also happens, if I start the subscriber before I start the
>     publisher.
>
>     Any ideas?
>
>     Sebastian Schneider
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>
>
> --
> Ugo Cupcic | Shadow Robot Company | ugo at shadowrobot.com
> <mailto:ugo at shadowrobot.com>
> Software Engineer | 251 Liverpool Road |
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>
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