Service Server and Publisher using same Node

edit

But ofcourse lots of errors and lots of problems when compiling.

You should have posted those errors in the question. Anyway, there is only 1 big problem which is fixed below:

service_server = n.advertiseService("add_two_ints", &SubscribeAndPublish::add, this);

You forgot to pass this while calling advertiseService( ... ). Below is the complete working code:

#include "ros/ros.h"
#include "beginner_tutorials/AddTwoInts.h"
#include "std_msgs/String.h"

#include <sstream>

class SubscribeAndPublish
{
public:
  SubscribeAndPublish()
  {
    chatter_pub = n.advertise<std_msgs::String>("chatter", 1000);
    service_server = n.advertiseService("add_two_ints", &SubscribeAndPublish::add, this);
  }

  bool add(beginner_tutorials::AddTwoInts::Request& req, beginner_tutorials::AddTwoInts::Response& res)
  {
    std_msgs::String msg;

    if (req.a == 1)
    {
      msg.data = "hello world";

      chatter_pub.publish(msg);
    }

    res.sum = req.a + req.b;
    ROS_INFO("request: x=%ld, y=%ld", (long int)req.a, (long int)req.b);
    ROS_INFO("sending back response: [%ld]", (long int)res.sum);
    return true;
  }

private:
  ros::NodeHandle n;
  ros::Publisher chatter_pub;
  ros::ServiceServer service_server;

};  // End of class SubscribeAndPublish

int main(int argc, char** argv)
{
  ros::init(argc, argv, "add_two_ints_server");

  SubscribeAndPublish SAPObject;

  ROS_INFO("Ready to add two ints.");
  ros::spin();

  return 0;
}

This is how, I executed it:

• Terminal 1

  $ roscore
  

• Terminal 2

  $ rosrun beginner_tutorials subscribe_and_publish
  [ INFO] [1665654555.498672244]: Ready to add two ints.
  [ INFO] [1665654646.303484866]: request: x=1, y=2
  [ INFO] [1665654646.303565863]: sending back response: [3]
  [ INFO] [1665654648.388244758]: request: x=1, y=2
  [ INFO] [1665654648.388283809]: sending back response: [3]
  [ INFO] [1665654661.012366878]: request: x=11, y=22
  [ INFO] [1665654661.012465383]: sending back response: [33]
  

• Terminal 3

  $ rostopic echo /chatter 
  data: "hello world"
  ---
  data: "hello world"
  ---