ThignsBoard通过服务端订阅共享属性

MQTT基础

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指南中的说明。

MQTT连接

我们将在本文中使用令牌凭据对进行设备访问，这些凭证稍后将称为** $ACCESS_TOKEN** 应用程序需要发送用户名包含**$ 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

ThingsBoard 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；

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

通过服务端订阅属性

通过服务端订阅共享属性 必须SUBSCRIBE消息到下面主题：

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v1/devices/me/attributes

如果服务端组件（例如REST API或规则链）更改了共享属性时客户端就会收到对应属性值：

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{"key1":"value1"}

# Publish client-side attributes update. Replace $THINGSBOARD_HOST_NAME and $ACCESS_TOKEN with corresponding values.
mosquitto_pub -d -h "$THINGSBOARD_HOST_NAME" -t "v1/devices/me/attributes" -u "$ACCESS_TOKEN" -m "{"attribute1": "value1", "attribute2": true}"
# For example, $THINGSBOARD_HOST_NAME reference live demo server, $ACCESS_TOKEN is ABC123:
mosquitto_pub -d -h "demo.thingsboard.io" -t "v1/devices/me/attributes" -u "ABC123" -m "{"attribute1": "value1", "attribute2": true}"

# Publish client-side attributes update from file. Replace $THINGSBOARD_HOST_NAME and $ACCESS_TOKEN with corresponding values.
mosquitto_pub -d -h "$THINGSBOARD_HOST_NAME" -t "v1/devices/me/attributes" -u "$ACCESS_TOKEN" -f "new-attributes-values.json"
# For example, $THINGSBOARD_HOST_NAME reference live demo server, $ACCESS_TOKEN is ABC123:
mosquitto_pub -d -h "demo.thingsboard.io" -t "v1/devices/me/attributes" -u "ABC123" -f "new-attributes-values.json"


# Publish client-side attributes update from file. Replace $THINGSBOARD_HOST_NAME and $ACCESS_TOKEN with corresponding values.
mosquitto_pub -d -h "$THINGSBOARD_HOST_NAME" -t "v1/devices/me/attributes" -u "$ACCESS_TOKEN" -f "new-attributes-values.json"
# For example, $THINGSBOARD_HOST_NAME reference live demo server, $ACCESS_TOKEN is ABC123:
mosquitto_pub -d -h "demo.thingsboard.io" -t "v1/devices/me/attributes" -u "ABC123" -f "new-attributes-values.json"


# Publish client-side attributes update from file. Replace $THINGSBOARD_HOST_NAME and $ACCESS_TOKEN with corresponding values.
mosquitto_pub -d -h "$THINGSBOARD_HOST_NAME" -t "v1/devices/me/attributes" -u "$ACCESS_TOKEN" -f "new-attributes-values.json"
# For example, $THINGSBOARD_HOST_NAME reference live demo server, $ACCESS_TOKEN is ABC123:
mosquitto_pub -d -h "demo.thingsboard.io" -t "v1/devices/me/attributes" -u "ABC123" -f "new-attributes-values.json"

# Publish client-side attributes update. Replace $THINGSBOARD_HOST_NAME and $ACCESS_TOKEN with corresponding values.
cat new-attributes-values.json | mqtt pub -d -h "$THINGSBOARD_HOST_NAME" -t "v1/devices/me/attributes" -u '$ACCESS_TOKEN' -s -m ""
# For example, $THINGSBOARD_HOST_NAME reference live demo server, $ACCESS_TOKEN is ABC123:
cat new-attributes-values.json | mqtt pub -d -h "demo.thingsboard.io" -t "v1/devices/me/attributes" -u 'ABC123' -s -m ""