https://mqtt.org/

MQTT（Message Queuing Telemetry Transport）
一种轻量级的，基于发布订阅模式的通信协议，用于在物联网和机器与机器（M2M）通信中传输消息。
它具有低带宽和低功耗的特点，适用于连续连接不稳定的网络环境。

Lightweight and Efficient
轻量高效
MQTT clients are very small, require minimal resources so can be used on small microcontrollers. MQTT message headers are small to optimize network bandwidth.
MQTT 客户端非常小，需要最少的资源，因此可以在小型微控制器上使用。 MQTT 消息标头很小，可以优化网络带宽。

Bi-directional Communications
双向通讯
MQTT allows for messaging between device to cloud and cloud to device. This makes for easy broadcasting messages to groups of things.

Scale to Millions of Things
扩展到数百万个事物
MQTT can scale to connect with millions of IoT devices（数百万个物联网设备）.

Reliable Message Delivery
可靠的消息传输
Reliability of message delivery is important for many IoT use cases. This is why MQTT has 3 defined quality of service levels: 0 - at most once, 1- at least once, 2 - exactly once
消息传递的可靠性对于许多物联网用例来说非常重要
MQTT 有 3 个服务质量级别：
0 - 最多一次，1 - 至少一次，2 - 恰好一次

Support for Unreliable Networks
对不可靠网络的支持
Many IoT devices connect over unreliable cellular networks（不可靠的蜂窝网络）.
MQTT’s support for persistent sessions reduces the time to reconnect the client with the broker.
MQTT 对持久会话的支持减少了客户端与代理重新连接的时间。

Security Enabled
安全使能
MQTT makes it easy to encrypt messages using TLS and authenticate clients using modern authentication protocols, such as OAuth.
轻松使用 TLS 加密消息并使用 OAuth 等现代身份验证协议对客户端进行身份验证