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Empty service call is not executed

asked 2014-12-08 04:15:24 -0600

odelay gravatar image

I implemented the basic empty service as proposed by the tutorial in my program:

bool callback(std_srvs::Empty::Request& request, std_srvs::Empty::Response& response) {
    return true;
ros::NodeHandle * privateNodeHandle; 
int main(int argc, char **argv) { ros::init(argc, argv, node_name); ros::NodeHandle n; privateNodeHandle = new ros::NodeHandle("~"); privateNodeHandle->param("publishFrequency", publishFrequency, 1.0); privateNodeHandle->param("maximumWaterLevel", maximumWaterLevel, 1.0);
ros::Publisher water_level_pub = n.advertise<std_msgs::float64>( topic, 1000); ros::ServiceServer service = n.advertiseService("my_service", callback); ros::Rate loop_rate(publishFrequency);
tank = new WaterTank(maximumWaterLevel); int count = 0; while (ros::ok()) { std_msgs::Float64 msg; std::stringstream ss; ss << "Water level at " << count << " is " << tank->get_water_level(); = tank->get_water_level(); ROS_INFO("%s", ss.str().c_str()); water_level_pub.publish(msg); loop_rate.sleep(); ++count; } delete tank; delete privateNodeHandle; return 0; }
It compiles fine and I see the service with rosservice list. But when I try to call it rosservice call /my_service rosservice seems to wait for the service to finish and never returns. This is weird since it is a service with empty parameter and return signature. I also added some debug output to the callback and it seems like it never gets executed. Is there some service blocking part in my main loop?

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are you able to see your service in rosservice list ?

bvbdort gravatar image bvbdort  ( 2014-12-08 05:10:40 -0600 )edit

Yes it is listed by rosservice list

odelay gravatar image odelay  ( 2014-12-08 05:18:38 -0600 )edit

2 Answers

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answered 2014-12-08 05:54:38 -0600

odelay gravatar image

updated 2014-12-08 05:55:25 -0600

The solution is to add a ros::spinOnce(); to the while loop. It will process all pending callbacks and then return.

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If this works for you please mark the answer as correct.

BennyRe gravatar image BennyRe  ( 2014-12-08 06:41:29 -0600 )edit

answered 2018-01-02 00:22:48 -0600

No spaces behind "rosservice call /my_service" ,because it is a service with empty parameter。

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Asked: 2014-12-08 04:15:24 -0600

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Last updated: Dec 08 '14