assets/Programming-MQTT.html-8cd751bc.js

import{_ as t,C as e,O as p,P as o,ah as c,Q as n,U as s,ai as l,aW as i}from"./framework-62ad666a.js";const u={},r=n("h2",{id:"mqtt-协议",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#mqtt-协议","aria-hidden":"true"},"#"),s(" MQTT 协议")],-1),d={href:"http://mqtt.org/",target:"_blank",rel:"noopener noreferrer"},k=i(`<p>它被设计为一种非常轻量级的发布/订阅消息传递。</p><p>对于与需要较小代码占用和/或网络带宽非常宝贵的远程位置的连接很有用。</p><p>IoTDB 支持 MQTT v3.1（OASIS 标准）协议。 IoTDB 服务器包括内置的 MQTT 服务，该服务允许远程设备将消息直接发送到 IoTDB 服务器。</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="https://alioss.timecho.com/docs/img/github/78357432-0c71cf80-75e4-11ea-98aa-c43a54d469ce.png"><h3 id="内置-mqtt-服务" tabindex="-1"><a class="header-anchor" href="#内置-mqtt-服务" aria-hidden="true">#</a> 内置 MQTT 服务</h3><p>内置的 MQTT 服务提供了通过 MQTT 直接连接到 IoTDB 的能力。 它侦听来自 MQTT 客户端的发布消息，然后立即将数据写入存储。 MQTT 主题与 IoTDB 时间序列相对应。 消息有效载荷可以由 Java SPI 加载的<code>PayloadFormatter</code>格式化为事件，默认实现为<code>JSONPayloadFormatter</code> 默认的<code>json</code>格式化程序支持两种 json 格式以及由他们组成的json数组，以下是 MQTT 消息有效负载示例：</p><div class="language-json line-numbers-mode" data-ext="json"><pre class="language-json"><code> <span class="token punctuation">{</span>
      <span class="token property">&quot;device&quot;</span><span class="token operator">:</span><span class="token string">&quot;root.sg.d1&quot;</span><span class="token punctuation">,</span>
      <span class="token property">&quot;timestamp&quot;</span><span class="token operator">:</span><span class="token number">1586076045524</span><span class="token punctuation">,</span>
      <span class="token property">&quot;measurements&quot;</span><span class="token operator">:</span><span class="token punctuation">[</span><span class="token string">&quot;s1&quot;</span><span class="token punctuation">,</span><span class="token string">&quot;s2&quot;</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
      <span class="token property">&quot;values&quot;</span><span class="token operator">:</span><span class="token punctuation">[</span><span class="token number">0.530635</span><span class="token punctuation">,</span><span class="token number">0.530635</span><span class="token punctuation">]</span>
 <span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>或者</p><div class="language-json line-numbers-mode" data-ext="json"><pre class="language-json"><code> <span class="token punctuation">{</span>
      <span class="token property">&quot;device&quot;</span><span class="token operator">:</span><span class="token string">&quot;root.sg.d1&quot;</span><span class="token punctuation">,</span>
      <span class="token property">&quot;timestamps&quot;</span><span class="token operator">:</span><span class="token punctuation">[</span><span class="token number">1586076045524</span><span class="token punctuation">,</span><span class="token number">1586076065526</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
      <span class="token property">&quot;measurements&quot;</span><span class="token operator">:</span><span class="token punctuation">[</span><span class="token string">&quot;s1&quot;</span><span class="token punctuation">,</span><span class="token string">&quot;s2&quot;</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
      <span class="token property">&quot;values&quot;</span><span class="token operator">:</span><span class="token punctuation">[</span><span class="token punctuation">[</span><span class="token number">0.530635</span><span class="token punctuation">,</span><span class="token number">0.530635</span><span class="token punctuation">]</span><span class="token punctuation">,</span> <span class="token punctuation">[</span><span class="token number">0.530655</span><span class="token punctuation">,</span><span class="token number">0.530695</span><span class="token punctuation">]</span><span class="token punctuation">]</span>
 <span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>或者以上两者的JSON数组形式。</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="https://alioss.timecho.com/docs/img/github/78357469-1bf11880-75e4-11ea-978f-a53996667a0d.png"><h3 id="mqtt-配置" tabindex="-1"><a class="header-anchor" href="#mqtt-配置" aria-hidden="true">#</a> MQTT 配置</h3><p>默认情况下，IoTDB MQTT 服务从<code>\${IOTDB_HOME}/\${IOTDB_CONF}/iotdb-datanode.properties</code>加载配置。</p><p>配置如下：</p><table><thead><tr><th>名称</th><th style="text-align:center;">描述</th><th style="text-align:center;">默认</th></tr></thead><tbody><tr><td>enable_mqtt_service</td><td style="text-align:center;">是否启用 mqtt 服务</td><td style="text-align:center;">false</td></tr><tr><td>mqtt_host</td><td style="text-align:center;">mqtt 服务绑定主机</td><td style="text-align:center;">127.0.0.1</td></tr><tr><td>mqtt_port</td><td style="text-align:center;">mqtt 服务绑定端口</td><td style="text-align:center;">1883</td></tr><tr><td>mqtt_handler_pool_size</td><td style="text-align:center;">处理 mqtt 消息的处理程序池大小</td><td style="text-align:center;">1</td></tr><tr><td>mqtt_payload_formatter</td><td style="text-align:center;">mqtt 消息有效负载格式化程序</td><td style="text-align:center;">json</td></tr><tr><td>mqtt_max_message_size</td><td style="text-align:center;">mqtt 消息最大长度（字节）</td><td style="text-align:center;">1048576</td></tr></tbody></table><p>### 示例代码 以下是 mqtt 客户端将消息发送到 IoTDB 服务器的示例。</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">MQTT</span> mqtt <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">MQTT</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
mqtt<span class="token punctuation">.</span><span class="token function">setHost</span><span class="token punctuation">(</span><span class="token string">&quot;127.0.0.1&quot;</span><span class="token punctuation">,</span> <span class="token number">1883</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
mqtt<span class="token punctuation">.</span><span class="token function">setUserName</span><span class="token punctuation">(</span><span class="token string">&quot;root&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
mqtt<span class="token punctuation">.</span><span class="token function">setPassword</span><span class="token punctuation">(</span><span class="token string">&quot;root&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token class-name">BlockingConnection</span> connection <span class="token operator">=</span> mqtt<span class="token punctuation">.</span><span class="token function">blockingConnection</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
connection<span class="token punctuation">.</span><span class="token function">connect</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token class-name">Random</span> random <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> <span class="token number">10</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   <span class="token class-name">String</span> payload <span class="token operator">=</span> <span class="token class-name">String</span><span class="token punctuation">.</span><span class="token function">format</span><span class="token punctuation">(</span><span class="token string">&quot;{\\n&quot;</span> <span class="token operator">+</span>
           <span class="token string">&quot;\\&quot;device\\&quot;:\\&quot;root.sg.d1\\&quot;,\\n&quot;</span> <span class="token operator">+</span>
           <span class="token string">&quot;\\&quot;timestamp\\&quot;:%d,\\n&quot;</span> <span class="token operator">+</span>
           <span class="token string">&quot;\\&quot;measurements\\&quot;:[\\&quot;s1\\&quot;],\\n&quot;</span> <span class="token operator">+</span>
           <span class="token string">&quot;\\&quot;values\\&quot;:[%f]\\n&quot;</span> <span class="token operator">+</span>
           <span class="token string">&quot;}&quot;</span><span class="token punctuation">,</span> <span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> random<span class="token punctuation">.</span><span class="token function">nextDouble</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

   connection<span class="token punctuation">.</span><span class="token function">publish</span><span class="token punctuation">(</span><span class="token string">&quot;root.sg.d1.s1&quot;</span><span class="token punctuation">,</span> payload<span class="token punctuation">.</span><span class="token function">getBytes</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token class-name">QoS</span><span class="token punctuation">.</span><span class="token constant">AT_LEAST_ONCE</span><span class="token punctuation">,</span> <span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

connection<span class="token punctuation">.</span><span class="token function">disconnect</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="自定义-mqtt-消息格式" tabindex="-1"><a class="header-anchor" href="#自定义-mqtt-消息格式" aria-hidden="true">#</a> 自定义 MQTT 消息格式</h3><p>事实上可以通过简单编程来实现 MQTT 消息的格式自定义。 可以在源码的 <code>example/mqtt-customize</code> 项目中找到一个简单示例。</p><p>步骤:</p><ul><li>创建一个 Java 项目，增加如下依赖</li></ul><div class="language-xml line-numbers-mode" data-ext="xml"><pre class="language-xml"><code>        <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>dependency</span><span class="token punctuation">&gt;</span></span>
            <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>groupId</span><span class="token punctuation">&gt;</span></span>org.apache.iotdb<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>groupId</span><span class="token punctuation">&gt;</span></span>
            <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>artifactId</span><span class="token punctuation">&gt;</span></span>iotdb-server<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>artifactId</span><span class="token punctuation">&gt;</span></span>
            <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>version</span><span class="token punctuation">&gt;</span></span>\${project.version}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>version</span><span class="token punctuation">&gt;</span></span>
        <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>dependency</span><span class="token punctuation">&gt;</span></span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><ul><li>创建一个实现类，实现接口 <code>org.apache.iotdb.db.protocol.mqtt.PayloadFormatter</code></li></ul><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token keyword">package</span> <span class="token namespace">org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>iotdb<span class="token punctuation">.</span>mqtt<span class="token punctuation">.</span>server</span><span class="token punctuation">;</span>

<span class="token keyword">import</span> <span class="token import"><span class="token namespace">io<span class="token punctuation">.</span>netty<span class="token punctuation">.</span>buffer<span class="token punctuation">.</span></span><span class="token class-name">ByteBuf</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>iotdb<span class="token punctuation">.</span>db<span class="token punctuation">.</span>protocol<span class="token punctuation">.</span>mqtt<span class="token punctuation">.</span></span><span class="token class-name">Message</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">org<span class="token punctuation">.</span>apache<span class="token punctuation">.</span>iotdb<span class="token punctuation">.</span>db<span class="token punctuation">.</span>protocol<span class="token punctuation">.</span>mqtt<span class="token punctuation">.</span></span><span class="token class-name">PayloadFormatter</span></span><span class="token punctuation">;</span>

<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>nio<span class="token punctuation">.</span>charset<span class="token punctuation">.</span></span><span class="token class-name">StandardCharsets</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span></span><span class="token class-name">ArrayList</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span></span><span class="token class-name">Arrays</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span></span><span class="token class-name">List</span></span><span class="token punctuation">;</span>

<span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">CustomizedJsonPayloadFormatter</span> <span class="token keyword">implements</span> <span class="token class-name">PayloadFormatter</span> <span class="token punctuation">{</span>

    <span class="token annotation punctuation">@Override</span>
    <span class="token keyword">public</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">Message</span><span class="token punctuation">&gt;</span></span> <span class="token function">format</span><span class="token punctuation">(</span><span class="token class-name">ByteBuf</span> payload<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token comment">// Suppose the payload is a json format</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>payload <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">return</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>

        <span class="token class-name">String</span> json <span class="token operator">=</span> payload<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token class-name">StandardCharsets</span><span class="token punctuation">.</span><span class="token constant">UTF_8</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token comment">// parse data from the json and generate Messages and put them into List&lt;Meesage&gt; ret</span>
        <span class="token class-name">List</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">Message</span><span class="token punctuation">&gt;</span></span> ret <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token punctuation">&gt;</span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token comment">// this is just an example, so we just generate some Messages directly</span>
        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> <span class="token number">2</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">long</span> ts <span class="token operator">=</span> i<span class="token punctuation">;</span>
            <span class="token class-name">Message</span> message <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Message</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            message<span class="token punctuation">.</span><span class="token function">setDevice</span><span class="token punctuation">(</span><span class="token string">&quot;d&quot;</span> <span class="token operator">+</span> i<span class="token punctuation">)</span><span class="token punctuation">;</span>
            message<span class="token punctuation">.</span><span class="token function">setTimestamp</span><span class="token punctuation">(</span>ts<span class="token punctuation">)</span><span class="token punctuation">;</span>
            message<span class="token punctuation">.</span><span class="token function">setMeasurements</span><span class="token punctuation">(</span><span class="token class-name">Arrays</span><span class="token punctuation">.</span><span class="token function">asList</span><span class="token punctuation">(</span><span class="token string">&quot;s1&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;s2&quot;</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            message<span class="token punctuation">.</span><span class="token function">setValues</span><span class="token punctuation">(</span><span class="token class-name">Arrays</span><span class="token punctuation">.</span><span class="token function">asList</span><span class="token punctuation">(</span><span class="token string">&quot;4.0&quot;</span> <span class="token operator">+</span> i<span class="token punctuation">,</span> <span class="token string">&quot;5.0&quot;</span> <span class="token operator">+</span> i<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
            ret<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>message<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
        <span class="token keyword">return</span> ret<span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token annotation punctuation">@Override</span>
    <span class="token keyword">public</span> <span class="token class-name">String</span> <span class="token function">getName</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token comment">// set the value of mqtt_payload_formatter in iotdb-datanode.properties as the following string:</span>
        <span class="token keyword">return</span> <span class="token string">&quot;CustomizedJson&quot;</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><ul><li>修改项目中的 <code>src/main/resources/META-INF/services/org.apache.iotdb.db.protocol.mqtt.PayloadFormatter</code> 文件: 将示例中的文件内容清除，并将刚才的实现类的全名（包名.类名）写入文件中。注意，这个文件中只有一行。 在本例中，文件内容为: <code>org.apache.iotdb.mqtt.server.CustomizedJsonPayloadFormatter</code></li><li>编译项目生成一个 jar 包: <code>mvn package -DskipTests</code></li></ul><p>在 IoTDB 服务端:</p><ul><li>创建 \${IOTDB_HOME}/ext/mqtt/ 文件夹, 将刚才的 jar 包放入此文件夹。</li><li>打开 MQTT 服务参数. (<code>enable_mqtt_service=true</code> in <code>conf/iotdb-datanode.properties</code>)</li><li>用刚才的实现类中的 getName() 方法的返回值 设置为 <code>conf/iotdb-datanode.properties</code> 中 <code>mqtt_payload_formatter</code> 的值， , 在本例中，为 <code>CustomizedJson</code></li><li>启动 IoTDB</li><li>搞定.</li></ul><p>More: MQTT 协议的消息不限于 json，你还可以用任意二进制。通过如下函数获得： <code>payload.forEachByte()</code> or <code>payload.array</code>。</p>`,28);function m(v,g){const a=e("ExternalLinkIcon");return p(),o("div",null,[c(`

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    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at
    
        http://www.apache.org/licenses/LICENSE-2.0
    
    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
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    under the License.

`),r,n("p",null,[n("a",d,[s("MQTT"),l(a)]),s(" 是机器对机器（M2M）/“物联网”连接协议。")]),k])}const q=t(u,[["render",m],["__file","Programming-MQTT.html.vue"]]);export{q as default};