以MQTT为例，用C++实现物联网设备通信协议与数据处理

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    物联网设备中的C ++的通信协议实现和数据处理

    随着物联网（IoT）的快速发展，各种类型的设备通过通信，传输和接收数据。 C ++是一种广泛使用的语言，特别适用于嵌入式系统。在本文中，我们将讨论如何使用C ++在物联网设备和过程数据之间实现通信协议。我们将以MQTT（）协议为例。这是一个轻巧的消息发布/订阅协议，非常适合带宽和有限功率的物联网设备。

    MQTT简介

    MQTT是客户端服务器模型发布/订阅消息传输协议。它允许客户端（例如传感器）将消息发送到代理服务器，而其他客户端可以从代理服务器订阅这些消息。

    MQTT的工作原理

    连接：IoT设备连接到MQTT代理作为客户端。

    发布：如果设备有新数据，它将将此信息发布到特定主题（主题）。

    订阅：其他设备可以订阅感兴趣的主题以接收相关新闻。

   

    QoS（服务质量）：MQTT支持不同级别的质量保证机制，以确保可以可靠地传递该消息。

    开发环境的准备

    这是您需要安装的一些重要工具：

    C ++编译器，例如G ++

    MQTT客户库库，例如PAHO MQTT C ++库

    创建您的开发项目目录并配置相应的文件。

    安装PAHO MQTT C ++库

    在类似Unix的系统上，可以运行以下命令：

   

<p style='margin-bottom:15px;color:#555555;font-size:15px;line-height:200%;text-indent:2em;'>    <pre class="code-snippet__js" data-lang=""><code><span leaf=""><span class="code-snippet__plaintext">ounter(line</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">sudo apt install libpaho-mqttpp3-dev</span></span></code></pre></p>
    对于用户，您可以从官方网站下载PAHO，并根据相应的指南进行安装。

    示例代码：MQTT发布者和订户实现

    以下是一个简单的MQTT 和带有C ++的订户示例代码。这两个代码显示了如何建立部分或远程连接，发送和接收信息。

    （）

    首先创建.cpp文件并编写以下内容：

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class="code-snippet__string">"tcp://broker.hivemq.com:1883"</span><span class="code-snippet__plaintext">);</span></span></code><code><span leaf=""><span class="code-snippet__keyword">const</span><span class="code-snippet__plaintext"> std::</span><span class="code-snippet__variable">string</span><span class="code-snippet__plaintext"> </span><span class="code-snippet__title">CLIENT_ID</span><span class="code-snippet__plaintext">(</span><span class="code-snippet__string">"ExamplePublisher"</span><span class="code-snippet__plaintext">);</span></span></code><code><span leaf=""><span class="code-snippet__keyword">const</span><span class="code-snippet__plaintext"> std::</span><span class="code-snippet__variable">string</span><span class="code-snippet__plaintext"> </span><span class="code-snippet__title">TOPIC</span><span class="code-snippet__plaintext">(</span><span class="code-snippet__string">"iot/sensor"</span><span class="code-snippet__plaintext">);</span></span></code><code><span 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Message #"</span><span class="code-snippet__plaintext"> + std::</span><span class="code-snippet__title">to_string</span><span class="code-snippet__plaintext">(i);</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">            publisher.</span><span class="code-snippet__title">publish</span><span class="code-snippet__plaintext">(TOPIC, payload.</span><span class="code-snippet__title">c_str</span><span class="code-snippet__plaintext">(), payload.</span><span class="code-snippet__title">size</span><span class="code-snippet__plaintext">(), </span><span class="code-snippet__number">0</span><span class="code-snippet__plaintext">);</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">            std::</span><span class="code-snippet__variable">cout</span><span class="code-snippet__plaintext"> << </span><span class="code-snippet__string">"Published: "</span><span class="code-snippet__plaintext"> << payload << </span><span class="code-snippet__string">'\n'</span><span class="code-snippet__plaintext">;</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">            </span><span class="code-snippet__title">sleep</span><span class="code-snippet__plaintext">(</span><span class="code-snippet__number">1</span><span class="code-snippet__plaintext">); // 暂停一秒钟再发送下一条信息</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">        }</span></span></code><code><span leaf=""><br  /></span></code><code><span leaf=""><span class="code-snippet__plaintext">        publisher.</span><span class="code-snippet__title">disconnect</span><span class="code-snippet__plaintext">();</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">    } </span><span class="code-snippet__keyword">catch</span><span class="code-snippet__plaintext"> (</span><span class="code-snippet__keyword">const</span><span class="code-snippet__plaintext"> mqtt::</span><span class="code-snippet__variable">exception</span><span class="code-snippet__plaintext">& exc) {</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">        std::</span><span class="code-snippet__variable">cerr</span><span class="code-snippet__plaintext"> << exc.</span><span class="code-snippet__title">what</span><span class="code-snippet__plaintext">() << </span><span class="code-snippet__string">"\n"</span><span class="code-snippet__plaintext">;</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">    }</span></span></code><code><span leaf=""><br  /></span></code><code><span leaf=""><span class="code-snippet__plaintext">    </span><span class="code-snippet__keyword">return</span><span class="code-snippet__plaintext"> </span><span class="code-snippet__number">0</span><span class="code-snippet__plaintext">;</span></span></code><code><span leaf=""><span class="code-snippet__plaintext">}</span></span></code></pre></p>