ros2-docs/docs/General ROS 2/Building ROS 2 Packages/ROS 2 Publisher.md

ROS 2 Publisher

Sample Code

Here is the code for creating a node that publishes strings to /robot_news at 2Hz.

=== "Python" ``` python title="robot_news_station.py" linenums="1" #!/usr/bin/env python import rclpy from rclpy.node import Node # import message type from example_interfaces.msg import String

class RobotNewsStationNode(Node):
	def __init__(self):
		super().__init__("robot_news_station")

		# Create publisher with the proper message type
		self.publisher_ = self.create_publisher(String, "robot_news", 10)
		# Create timer to triger message at 2Hz
		self.timer_ = self.create_timer(0.5, self.publish_news)
		self.get_logger().info("Starting the robot news station")

	def publish_news(self):
		# Create massage payload
		msg = String()
		# Add 'Hello' as the data
		msg.data = "Hello"
		# Publish the data payload
		self.publisher_.publish(msg)

	  
def main (args=None):
	rclpy.init(args=args)
	node = RobotNewsStationNode()
	rclpy.spin(node)
	rclpy.shutdown()


if __name__ == '__main__':
	main()
```

=== "C++" ``` python title="robot_news_station.cpp" linenums="1" #include "rclcpp/rclcpp.hpp" #include "example_interfaces/msg/string.hpp"

class RobotNewsStationNode : public rclcpp::Node
{
	public:
		RobotNewsStationNode() : Node("robot_news_station")
		{
			publisher_ = this->create_publisher<example_interfaces::msg::String>("robot_news", 10);
			timer_ = this->create_wall_timer(std::chrono::milliseconds(500),
											std::bind(&RobotNewsStationNode::publishNews, this));
			RCLCPP_INFO(this->get_logger(),"Robot News Station has been started.");
		}

private:
	void publishNews()
	{
		auto msg = example_interfaces::msg::String();
		msg.data = std::string("Hi, this is") + robot_name_ + std::string(" from the Robot News Station") ;
		publisher_->publish(msg);
	}

	std::string robot_name_;
	rclcpp::Publisher<example_interfaces::msg::String>::SharedPtr publisher_;
	rclcpp::TimerBase::SharedPtr timer_;
};

int main(int argc, char **argv)
{
	rclcpp::init(argc, argv);
	auto node = std::make_shared<RobotNewsStationNode>();
	rclcpp::spin(node);
	rclcpp::shutdown();
	return 0;
}
```