Why does service not work from launch file ?

asked 2021-07-06 23:05:00 -0600

elpidiovaldez
142 ●22 ●31 ●36

I create a permanent service, and its client in my launch file. All subsequent service calls fail. I have discovered that if I kill the client and run it from the command line, then the service calls work. The service also works if I call it directly from the command line using 'rosservice'.

I have also discovered that making the service temporary solves the issue. I suspect that the launch file does something before the service is ready, but I don't know what.

I still want to use a permanent service for efficiency. What can I do to fix the problem ?

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Is permanent actually persistent here?

gvdhoorn ( 2021-07-07 04:08:35 -0600 )edit

Yes, I did mean 'persistent'. I don't even remember where I got the idea they were called 'permanent' connections now. It was something I read while investigating them.

elpidiovaldez ( 2021-07-12 11:28:04 -0600 )edit

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answered 2021-07-12 12:11:56 -0600

elpidiovaldez
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I found a discussion on ROS Answers which solved the issue for me. It is here.

I simply needed to wait for the service to be created, by the launch file, before I create the service client. The way to do it is shown below:

void InitializeTTS(ros::NodeHandle &n) {
  ros::service::waitForService("/tts");
  TTSclient = n.serviceClient<tts_serv::Gtts>("/tts",true);
}

Thanks to @appie for the advice. I looked at rosparam documentation, but I could not see how to use it to solve my issue.

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answered 2021-07-07 02:44:34 -0600

appie
11 ●2 ●4 ●5

roslaunch used to run nodes and setting parameters. So you need to start the service within your node using rosparam and getting the parameters from the launch file

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Why does service not work from launch file ?

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