.. vim: syntax=rst

.. highlight:: sh

C#
============================

本文主要介绍如何在 C# 项目中使用 paho.mqtt.m2mqtt 客户端库 ，实现客户端与 SX-IOT物联网设备的连接、订阅、收发消息等功能。

C# 是微软推出的一种基于 .NET框架的、 面向对象 的高级编程语言。 C#是一种由C和C++派生出来的面向对象的编程语言。 它在继承C和C++强大功能的同时去掉了一些它们的复杂特性，使其成为C语言家族中的一种高效强大的编程语言。

前提条件
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

安装依赖包
------------------
.. code-block:: bash
   :linenos:

   sudo apt remove 'dotnet*' 'aspnet*' 'netstandard*'
   sudo rm /etc/apt/sources.list.d/microsoft-prod.list
   sudo apt update
   sudo apt install dotnet-sdk-6.0
   dotnet --version
   dotnet new console -o mqtt-client-Csharp-paho
   cd mqtt-client-Csharp-paho
   dotnet add package M2Mqtt --version 4.3.0




连接使用
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
连接设置
------------------

本文将使用自定义的接入认证方式，服务器接入信息如下：

- Broker: **mqtt.geek-smart.cn**
- TCP Port: **1883**
- WebSocket Port: **8083**

导入依赖包
------------------
.. code-block:: csharp
   :linenos:

    using System;
    using uPLibrary.Networking.M2Mqtt;
    using uPLibrary.Networking.M2Mqtt.Messages;

定义连接地址、认证信息以及消息发布主题
------------------

设置 MQTT Broker 连接地址，端口以及 topic。

.. code-block:: csharp
   :linenos:

    string broker = "mqtt.geek-smart.cn";
    int port = 1883;
    string pub_topic = "/HYUGHV/lVtAcHuor***/4cebd60bf***/publish";
    string sub_topic = "/HYUGHV/lVtAcHuor***/4cebd60bf***/subscribe";
    string clientId = "csharp-client";
    string username = "************";
    string password = "************";


定义消息发布函数
------------------
.. code-block:: csharp
   :linenos:

    static void Publish(MqttClient client, string topic)
    {
        int msg_count = 0;
        while (true)
        {
            System.Threading.Thread.Sleep(1*1000);
            string msg = "{'type':'info'}";
            client.Publish(topic, System.Text.Encoding.UTF8.GetBytes(msg));
            Console.WriteLine("Send `{0}` to topic `{1}`", msg, topic);
            msg_count++;
        }
    }


定义 subscribe 回调函数，用于打印订阅主题接收的消息内容
------------------------------------------------------------------------
.. code-block:: csharp
   :linenos:

    static void Subscribe(MqttClient client, string topic)
    {
        client.MqttMsgPublishReceived += client_MqttMsgPublishReceived;
        client.Subscribe(new string[] { topic }, new byte[] { MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE });
    }
    static void client_MqttMsgPublishReceived(object sender,MqttMsgPublishEventArgs e)
    {
        string payload = System.Text.Encoding.Default.GetString(e.Message);
        Console.WriteLine("Received `{0}` from `{1}` topic", payload, e.Topic.ToString());
    }



初始化 MQTT 客户端并订阅主题
------------------------------------------------------------------------
.. code-block:: csharp
   :linenos:

    static MqttClient ConnectMQTT(string broker, int port, stringclientId, string username, string password)
    {
        MqttClient client = new MqttClient(broker, port, false, MqttSslProtocols.None, null, null);
        client.Connect(clientId, username, password);
        if (client.IsConnected)
        {
            Console.WriteLine("Connected to MQTT Broker");
        }
        else
        {
            Console.WriteLine("Failed to connect");
        }
        return client;
    }


完整代码
------------------------------------------------------------------------

.. code-block:: xml
   :linenos:

   <Project Sdk="Microsoft.NET.Sdk">
   
     <PropertyGroup>
       <OutputType>Exe</OutputType>
       <TargetFramework>net6.0</TargetFramework>
       <RootNamespace>mqtt_client_Csharp_paho</RootNamespace>
       <ImplicitUsings>enable</ImplicitUsings>
       <Nullable>enable</Nullable>
     </PropertyGroup>
   
     <ItemGroup>
       <PackageReference Include="M2Mqtt" Version="4.3.0" />
     </ItemGroup>
   
   </Project>


.. code-block:: csharp
   :linenos:

    using System;
    using uPLibrary.Networking.M2Mqtt;
    using uPLibrary.Networking.M2Mqtt.Messages;

    namespace csharpMQTT
    {
        class Program
        {
            static MqttClient ConnectMQTT(string broker, int port, string clientId, string username, string password)
            {
                MqttClient client = new MqttClient(broker, port, false, MqttSslProtocols.None, null, null);
                client.Connect(clientId, username, password);
                if (client.IsConnected)
                {
                    Console.WriteLine("Connected to MQTT Broker");
                }
                else
                {
                    Console.WriteLine("Failed to connect");
                }
                return client;
            }

            static void Publish(MqttClient client, string topic)
            {
                int msg_count = 0;
                while (true)
                {
                    System.Threading.Thread.Sleep(1*1000);
                    string msg = "{'type':'info'}";
                    client.Publish(topic, System.Text.Encoding.UTF8.GetBytes(msg));
                    Console.WriteLine("Send `{0}` to topic `{1}`", msg, topic);
                    msg_count++;
                }
            }

            static void Subscribe(MqttClient client, string topic)
            {
                client.MqttMsgPublishReceived += client_MqttMsgPublishReceived;
                client.Subscribe(new string[] { topic }, new byte[] { MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE });
            }
            static void client_MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
            {
                string payload = System.Text.Encoding.Default.GetString(e.Message);
                Console.WriteLine("Received `{0}` from `{1}` topic", payload, e.Topic.ToString());
            }

            static void Main(string[] args)
            {
                string broker = "mqtt.geek-smart.cn";
                int port = 1883;
                string pub_topic = "/HYUGHV/lVtAcHuor***/4cebd60bf***/publish";
                string sub_topic = "/HYUGHV/lVtAcHuor***/4cebd60bf***/subscribe";
                string clientId = "csharp-client";
                string username = "************";
                string password = "************";
                MqttClient client = ConnectMQTT(broker, port, clientId, username, password);
                Subscribe(client, sub_topic);
                Publish(client, pub_topic);
            }
        }
    }




测试验证
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

运行
------------------------------------------------------------------------
.. code-block:: bash
   :linenos:

   dotnet run