我的mqtt协议和emqttd开源项目个人理解（5） - hook的使用，源码分析

学习mqtt协议和emqttd开源项目emqtt.com/

emqttd源码版本号是v1.1.3。emqtt.com/downloads/1…

\

1、-module(emqttd_app).

start(_StartType, _StartArgs) ->
load_all_mods(),

\

2、读取emqttd.config文件，modules字段

%% Modules
    {modules, [
        %% Client presence management module.
        %% Publish messages when client connected or disconnected
        {presence, [{qos, 0}]},

        %% Subscribe topics automatically when client connected
        {subscription, [

            %% $c will be replaced by clientid
            %% {"$queue/clients/$c", 1},

            %% Static subscriptions from backend
            backend
        ]}

        %% Rewrite rules
        %% {rewrite, [{file, "etc/rewrite.config"}]}
    ]},

3、加载
-module(emqttd_mod_presence).\

load(Opts) ->
    emqttd:hook('client.connected', fun ?MODULE:on_client_connected/3, [Opts]),
    emqttd:hook('client.disconnected', fun ?MODULE:on_client_disconnected/3, [Opts]).

具体某个节点的某个clientId方式的主题是：

$SYS/brokers/emqttd@172.16.6.161/clients/861694030142478/connected
$SYS/brokers/emqttd@172.16.6.161/clients/861694030142478/disconnected\

\

-module(emqttd_mod_subscription).
load(Opts) ->\