如何基于ignition开发mqtt模块?
时间: 2023-07-07 12:17:30 浏览: 180
基于qt的mqtt实现,源代码
您好!针对您的问题,基于Ignition开发MQTT模块需要进行以下步骤:
1. 安装mosquitto库
在Ubuntu系统下,您可以使用以下命令安装mosquitto库:
```
sudo apt-get install libmosquitto-dev
```
2. 创建ROS package
使用以下命令创建ROS package:
```
catkin_create_pkg mqtt_ros std_msgs rospy roscpp
```
其中,mqtt_ros是package的名称,std_msgs、rospy和roscpp是依赖项。
3. 编写MQTT客户端程序
在package目录下创建一个名为mqtt_client.cpp的文件,编写MQTT客户端程序。在程序中,您需要引入mosquitto.h头文件,创建MQTT客户端实例,并设置回调函数。
您可以参考以下代码:
```c++
#include <mosquitto.h>
#include <ros/ros.h>
#include <std_msgs/String.h>
void on_connect(struct mosquitto *mosq, void *obj, int rc)
{
ROS_INFO("Connected with MQTT broker");
}
void on_message(struct mosquitto *mosq, void *obj, const struct mosquitto_message *msg)
{
ROS_INFO("Received message: %s", (char *)msg->payload);
}
int main(int argc, char *argv[])
{
mosquitto_lib_init();
struct mosquitto *mosq = mosquitto_new(NULL, true, NULL);
if (!mosq) {
ROS_ERROR("Failed to create MQTT client instance");
return -1;
}
mosquitto_connect_callback_set(mosq, on_connect);
mosquitto_message_callback_set(mosq, on_message);
int rc = mosquitto_connect(mosq, "localhost", 1883, 60);
if (rc != MOSQ_ERR_SUCCESS) {
ROS_ERROR("Failed to connect to MQTT broker");
return -1;
}
mosquitto_subscribe(mosq, NULL, "test/topic", 0);
ros::init(argc, argv, "mqtt_ros");
ros::NodeHandle nh;
ros::Publisher pub = nh.advertise<std_msgs::String>("mqtt_topic", 10);
ros::Rate rate(10);
while (ros::ok()) {
std_msgs::String msg;
msg.data = "Hello, MQTT!";
pub.publish(msg);
mosquitto_loop(mosq, 0, 1);
ros::spinOnce();
rate.sleep();
}
mosquitto_disconnect(mosq);
mosquitto_destroy(mosq);
mosquitto_lib_cleanup();
return 0;
}
```
4. 编译程序
使用以下命令编译程序:
```
catkin_make
```
5. 运行程序
使用以下命令运行程序:
```
rosrun mqtt_ros mqtt_client
```
至此,基于Ignition开发MQTT模块的步骤就完成了。当您运行程序时,MQTT客户端将连接到本地MQTT broker,并订阅"test/topic"主题。同时,ROS节点将发布"mqtt_topic"主题。当MQTT broker接收到来自"test/topic"主题的消息时,回调函数on_message将被调用;当ROS节点发布"mqtt_topic"主题时,消息将被发送到MQTT broker。
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