https://github.com/wizinfantry/delphi-mqtt-client
https://github.com/Indemsys/Delphi_MQTT_mosquitto
https://github.com/jamiei/Delphi-TMQTT2
http://bbs.2ccc.com/topic.asp?topicid=528798
EMQ 2.1.0-beta.1 发布, 百万级 MQTT 消息服务器
https://www.oschina.net/news/82245/emq-2-1-o-beta-1