#EMQ version 2.0 officially released

EMQ-2.0 version is officially released! The EMQ-2.0 version reconstructs the entire project architecture and officially supports the shared subscription function:
supports Shared Subscription and Local Subscription to solve the MQTT protocol load balancing consumption problem;
supports CoAP (RFC 7252), MQTT-SN Protocol and gateway, support CoAP, MQTT-SN client and MQTT client interworking;
refactor configuration file format and loading method, support user-friendly 'K = V' file format, support operating system environment variables;
add extension hooks and A large number of authentication plug-ins support authentication integration with most databases or NoSQL;
support compilation and deployment on all platforms, Linux/Unix/Windows and ARM platform gateways, and support Docker image creation.

Shared Subscription
Shared Subscription supports group load balancing among multiple subscribers to distribute messages:
                                ---------
                                | | --Msg1--> Subscriber1
    Publisher--Msg1,Msg2 ,Msg3-->| EMQ | --Msg2--> Subscriber2
                                | | --Msg3--> Subscriber3
                                ---------
How to use: Subscribers add a '$queue' or '$share//' prefix to the topic (Topic).
Local Subscription
Local Subscription only creates subscription and routing tables on this node, and does not broadcast global routes between cluster nodes, which is very suitable for IoT data collection applications.
How to use: Subscribers add the '$local/' prefix to the topic (Topic).
erlang.mk and relx
2.0 are separated from the main emqttd project and the release project emq-relx. The erlang.mk and relx compilation and release tools are used to replace the rebar used in the 1.x version. The project can be compiled under Linux/Unix/Windows systems across platforms.
CoAP protocol support
Version 2.0 supports CoAP protocol (RFC7252), and supports the interworking between CoAP gateway and MQTT client.
CoAP plugin: https://github.com/emqtt/emq_coap
MQTT-SN protocol support
version 2.0 supports MQTT-SN protocol, and supports the interworking between MQTT-SN gateway and MQTT client.
MQTT-SN plugin: https://github.com/emqtt/emq_sn
'K=V' format configuration file
Version 2.0 supports user-friendly 'K=V' format configuration file etc/emq.conf:
node.name = emqttd@ 127.0.0.1

    ...

    mqtt.listener.tcp=1883

    ...
OS Environment Variables
Version 2.0 supports OS environment variables. Set the EMQ node name, security cookie and TCP port number through environment variables at startup:
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EMQ_NODE_COOKIE=emq_dist_cookie
EMQ_MAX_PORTS=65536
EMQ_TCP_PORT=1883
EMQ_SSL_PORT=8883
EMQ_HTTP_PORT=8083
EMQ_HTTPS_PORT=8084
Docker image supports
EMQ-2.0 version Docker image production, Dockerfile open source at: https://github.com/emqtt/emq_docker
Windows platform supports
version 2.0, fully supports compilation, release and operation of Windows platform, supports 'emqttd_ctl' control command under Windows platform, and supports Windows nodes between clusters.
Issues and improvements
#764: add mqtt.cache_acl option
#667: Configuring emqttd from environment variables
#722: mqtt/superuser calls two times emqtt_auth_http
#754: "-heart" option for EMQ 2.0
#741: emq_auth_redis cannot use hostname as server address