MQTT Notes

Table of Contents

1 IOT Introduction

  • The term of IOT was first used by Kevin Ashton in 2009 for interconnecting physical devices over the internet.
  • scenario: Imagine your alarm clock would know that your train to work is 15 minutes late and adjust itself accordingly. Also your coffee maker is switched on automatically 15 minutes later to make you a hot cup of coffee before you leave for work.
  • Ericsson predicts that in 2020 50 billion devices are connected over the internet. The communication between the huge amount of devices is enabled by IPv6 and lightweight communication protocols like MQTT.

2 MQTT

  • 1999年由IBM的Andy Stranfor-Clark和Eurotech的Arlen Nipper开发,应用于监控 沙漠中的石油管道的项目。
  • 协议目标:
    • bandwidth-efficient. 低带宽占用
    • little battery power. 低功耗
    • low footprint.
  • 协议采用pubish/subscirbe架构,与 HTTP 协议的reques/reponse语义相 异。 mqtt0.png
    • event-driven, enables messages to be pushed to clients
    • MQTT broker: central communication point.
      • It is in charge of dispatching all messages between the senders and the rightful receivers.
    • Sensor/device publish info/data to broker.
    • Client want to recieve message subcribe to a certain topic to broker. And broker will delivers all messages with matching topic to this client.
    • hight scalable without dependenies between the data producers and the data consumers.
    • Push but not Pull
    • Topic: hierachized message router.就像RESTful之于http

3 Use Case

mqtt1.png

4 Implementation & Docs

Author: icicle

Created: 2017-03-02 Thu 01:21

Emacs 25.1.1 (Org mode 8.2.10)

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