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import{_ as o,r as p,o as c,c as i,a as l,d as s,e as n,b as t,f as e}from"./app-z4N-28Th.js";const u={},r=s("h1",{id:"mqtt-protocol",tabindex:"-1"},[s("a",{class:"header-anchor",href:"#mqtt-protocol","aria-hidden":"true"},"#"),n(" MQTT Protocol")],-1),d={href:"http://mqtt.org/",target:"_blank",rel:"noopener noreferrer"},k=s("br",null,null,-1),m=s("br",null,null,-1),v=e(`<p>IoTDB supports the MQTT v3.1(an OASIS Standard) protocol.<br> IoTDB server includes a built-in MQTT service that allows remote devices to send messages to an IoTDB server directly.</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"><h2 id="built-in-mqtt-service" tabindex="-1"><a class="header-anchor" href="#built-in-mqtt-service" aria-hidden="true">#</a> Built-in MQTT Service</h2><p>The built-in MQTT Service provides the ability of a direct connection to IoTDB using MQTT.<br> It listens for publish messages from MQTT clients and then writes the data into storage immediately.<br> The MQTT topic is directly mapped to the IoTDB timeseries used for persisting the data.<br> The messages payload can be formatted to events by using the <code>PayloadFormatter</code> which loaded by Java SPI.<br> The default implementation is <code>JSONPayloadFormatter</code>.<br> The default <code>json</code> formatter supports both accepting single json objects as well as arrays of json objects.</p><p>The following are two examples of valid MQTT message payloads:</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>or</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>or json array of the above two.</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"><h2 id="mqtt-configurations" tabindex="-1"><a class="header-anchor" href="#mqtt-configurations" aria-hidden="true">#</a> MQTT Configurations</h2><p>The IoTDB MQTT service load configurations from <code>\${IOTDB_HOME}/\${IOTDB_CONF}/iotdb-common.properties</code> by default.</p><p>The <code>IoTDB MQTT service</code> loads it&#39;s configuration from <code>\${IOTDB_HOME}/\${IOTDB_CONF}/iotdb-datanode.properties</code> per default.</p><p>The configuration options of this file are as follows:</p><table><thead><tr><th>NAME</th><th style="text-align:center;">DESCRIPTION</th><th style="text-align:center;">DEFAULT</th></tr></thead><tbody><tr><td>enable_mqtt_service</td><td style="text-align:center;">whether to enable the mqtt service</td><td style="text-align:center;">false</td></tr><tr><td>mqtt_host</td><td style="text-align:center;">the mqtt service binding host</td><td style="text-align:center;">127.0.0.1</td></tr><tr><td>mqtt_port</td><td style="text-align:center;">the mqtt service binding port</td><td style="text-align:center;">1883</td></tr><tr><td>mqtt_handler_pool_size</td><td style="text-align:center;">the handler pool size for handing the mqtt messages</td><td style="text-align:center;">1</td></tr><tr><td>mqtt_payload_formatter</td><td style="text-align:center;">the mqtt message payload formatter</td><td style="text-align:center;">json</td></tr><tr><td>mqtt_max_message_size</td><td style="text-align:center;">the max mqtt message size in byte</td><td style="text-align:center;">1048576</td></tr></tbody></table><h2 id="coding-examples" tabindex="-1"><a class="header-anchor" href="#coding-examples" aria-hidden="true">#</a> Coding Examples</h2><p>The following is an example which a mqtt client send messages to IoTDB server.</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 class="line-number"></div></div></div><h2 id="customize-your-mqtt-message-format" tabindex="-1"><a class="header-anchor" href="#customize-your-mqtt-message-format" aria-hidden="true">#</a> Customize your MQTT Message Format</h2><p>If you need a special format, you can customize your MQTT Message format by writing a few lines of codes.</p>`,20),g={href:"https://github.com/apache/iotdb/tree/master/example/mqtt-customize",target:"_blank",rel:"noopener noreferrer"},b=e(`<p>Steps:</p><ul><li>Create a java project, and add dependency:</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>1.1.0-SNAPSHOT<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>Create your implementation class which implements the <code>org.apache.iotdb.db.protocol.mqtt.PayloadFormatter</code> interface:</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>Update or create a file: <code>src/main/resources/META-INF/services/org.apache.iotdb.db.protocol.mqtt.PayloadFormatter</code> containing the fully qualified class name of your formatter.<br> (In the previous example, this would be adding a single line with this content: <code>org.apache.iotdb.mqtt.server.CustomizedJsonPayloadFormatter</code>)</li><li>compile your implementation into a jar file: <code>mvn package -DskipTests</code></li></ul><p>Then, in your server:</p><ul><li>Create an <code>\${IOTDB_HOME}/ext/mqtt/</code> folder, and put the jar into this directory.</li><li>Update configuration to enable MQTT service in <code>conf/iotdb-datanode.properties</code> by setting <code>enable_mqtt_service=true</code>.</li><li>Set the value of <code>mqtt_payload_formatter</code> in <code>conf/iotdb-datanode.properties</code> to the value you are returning in your implementation of getName().<br> (In this example, the value would be: <code>CustomizedJson</code>)</li><li>Launch the IoTDB server.</li><li>Now IoTDB will use your implementation to parse the MQTT message.</li></ul><p>More: the message format can be anything you want. For example, if it is a binary format,<br> just use <code>payload.forEachByte()</code> or <code>payload.array</code> to get bytes content.</p>`,9);function h(y,f){const a=p("ExternalLinkIcon");return c(),i("div",null,[l(`
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`),r,s("p",null,[s("a",d,[n("MQTT"),t(a)]),n(' is a machine-to-machine (M2M)/"Internet of Things" connectivity protocol.'),k,n(" It was designed as an extremely lightweight publish/subscribe messaging transport."),m,n(" It is useful for connections with remote locations where a small code footprint is required and/or network bandwidth is at a premium.")]),v,s("p",null,[n("An example can be found in "),s("a",g,[n("example/mqtt-customize"),t(a)]),n(" module.")]),b])}const T=o(u,[["render",h],["__file","Programming-MQTT.html.vue"]]);export{T as default};