# MQTT协议

### 入门 <a href="#ru-men" id="ru-men"></a>

**MQTT基础**

[MQTT](https://en.wikipedia.org/wiki/MQTT)是一种轻量级的发布-订阅消息传递协议，它可能最适合各种物联网设备。

你可以在[此处](http://mqtt.org/)找到有关MQTT的更多信息，ThingsBoard服务器支持QoS级别0（最多一次）和QoS级别1（至少一次）以及一组预定义主题的MQTT代理。

**客户端**

你可以在网上找到大量的MQTT客户端库，本文中的示例将基于Mosquitto和MQTT.js您可以使用我们的[Hello World](http://www.ithingsboard.com/docs/getting-started-guides/helloworld/)指南中的说明。

**MQTT连接**

我们将在本文中[使用令牌凭据](/she-bei-jie-ru/chuang-jian-she-bei.md#huo-qu-fang-wen-ling-pai)对进行设备访问，这些凭证稍后将称&#x4E3A;**$ACCESS\_TOKEN**应用程序需要发送用户名包&#x542B;**$ACCESS\_TOKEN**的MQTT CONNECT消息。

连接状态码说明：

* **0x00 连接成功** - 成功连接
* **0x04 连接失败** - 用户名或密码错误。
* **0x05 连接未授权** - -用户名包含无效的 **$ACCESS\_TOKEN**。

### Key-value格式 <a href="#keyvalue-ge-shi" id="keyvalue-ge-shi"></a>

支持以JSON格式的key-value字符串，值可以是string、bool、float、long或者二进制格式的序列化字符串；

### MQTT连接配置

```
47.106.143.1:1883
```

**userName**: GP1109N12345678（[在平台获取访问令牌](/she-bei-jie-ru/chuang-jian-she-bei.md#huo-qu-fang-wen-ling-pai)）\
**password**: (无)

### &#x20;**TOPIC主题发布接口列表**

|   | **topic**             | **Qos-级别** | **认证方式**    | **注释** |
| - | --------------------- | ---------- | ----------- | ------ |
| 1 | v1/gateway/connect    | 1          | accessToken | 连接到网关  |
| 2 | v1/gateway/disconnect | 1          | accessToken | 断开网关   |
| 3 | v1/gateway/attributes | 1          | accessToken | 设备属性   |
| 4 | v1/gateway/telemetry  | 1          | accessToken | 数据遥测   |

payload格式例如:

```
{
	"DEVICE": [{
		"ts": "1609144280398",
		"values": {
        "stringKey":"value1", 
        "booleanKey":true, 
        "doubleKey":42.0, 
        "longKey":73, 
        "jsonKey": {
           "someNumber": 42,
           "someArray": [1,2,3],
           "someNestedObject": {"key": "value"}
        }
       }
	}]
}

```

### v1/gateway/telemetry

网关心跳包实例：

```
{
	"WG12345678": [{
		"ts": "1609145640724",
		"values": {
			"H": "60",
			"mode": "2",
			"NET4GSTA": "1,0",
			"mT": "3,0,1",
			"mFifo": "618,618,1389,1389",
			"DDA": "1",
			"boxSta": "0",
			"TH": "30.40,42.4",
			"NR": "1247,1254",
			"Lat": "22.540456",
			"Lon": "113.928825",
			"SDR": 1,
			"power": {
				"0": 0,
				"1": "6.80",
				"2": "29",
				"9": "11.48",
				"10": "3800",
				"11": "3300",
				"12": "0",
				"13": "3300",
				"14": "40"
			}
		}
	}]
}
```

终端数据包实例：

```
{
	"WG12345678/sf_2_0_340000": [{
		"ts": "1609144280398",
		"values": {
			"T": "1609144280355",
			"SN": "00006500",
			"da": "010CE735CA7C271E21FFFFFF"
		}
	}]
}
```

###

在上面的示例中我们"ts":"1609144280398"，是具有毫秒精度的[Unix时间戳](https://en.wikipedia.org/wiki/Unix_time)。例如：值’1609140420031’转换后是’2020-12-28 16:31:20’。


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://doc.yuncitys.com/xie-yi-jie-kou/mqtt-1.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.