zoukankan html css js c++ java

物联网架构成长之路(8)-EMQ-Hook了解、连接Kafka发送消息

1. 前言

　　按照我自己设计的物联网框架，对于MQTT集群中的所有消息，是要持久化到磁盘的，这里采用一个消息队列中间件Kafka作为数据缓冲，缓冲结果存到数据仓库中，以供后续作为数据分析。由于MQTT集群中的消息都是比较分散的，所以使用Kafka来聚合、采集消息。

2. 下载&编译&安装

　　Kafka依赖ZooKeeper

　　在这里下载 http://mirrors.shuosc.org/apache/zookeeper/zookeeper-3.4.11/zookeeper-3.4.11.tar.gz

　　http://mirrors.shuosc.org/apache/kafka/1.0.0/kafka-1.0.0-src.tgz

　　http://mirror.bit.edu.cn/apache/kafka/1.0.0/kafka_2.12-1.0.0.tgz

　　学习的话，可以参考这个文档 http://orchome.com/kafka/index

　　配置使用过程可以参考官网的　http://kafka.apache.org/quickstart http://zookeeper.apache.org/doc/current/zookeeperStarted.html ，有些资料因为版本升级的原因，已经不是以前的那种启动方式了。https://cwiki.apache.org/confluence/display/KAFKA/Clients

3. 启动Zookeeper

1 cp ./conf/zoo_sample.cfg ./conf/zoo.cfg
2 ./bin/zkServer.sh start

　　上图，就表示启动单机模式。

　　./bin/zkCli.sh -server 127.0.0.1:2181 进行连接

　　然后进入命令行模式，可以慢慢玩了

　　单击模式就没有什么要配置的。最多修改zoo.cfg中的dataDir文件

　　ZooKeeper启动replicated模式，集群模式

　　zoo.cfg 增加服务器集群信息

1 server.1=172.16.20.229:2888:3888
2 server.2=172.16.23.203:2888:3888
3 server.3=172.16.23.204:2888:3888

1 ./bin/zkServer.sh start-foreground #启动

　　注意在echo “1” > %dataDir%/myid 对于每个服务器都要创建一个myid文件

　　启动都是会有一些奇奇怪怪的问题，上网找资料就可以了。

　　一般第一台ZooKeeper启动是会有Connection refused 出错，这个是正常的，后面的两台还没有启动，不过后面也一个一个启动了。

　　如果过程中，有一个断开了，然后修改数据，然后这个断开的又连上了，那么ZooKeeper集群内部会镜像diff

1 2017-12-28 16:30:38,570 [myid:3] - INFO  [QuorumPeer[myid=3]/0.0.0.0:2181:Learner@332] - Getting a diff from the leader 0x100000005

　　然后就用客户端A

1 ./bin/zkCli.sh -server 172.16.20.229:2181
2 ls /
3 create /zk_test my_data
4 ls /

　　然后用客户端B

1 ./bin/zkCli.sh -server 172.16.23.203:2181
2 ls /
3 get /zk_test
4 ls /

　　可以看到ZooKeeper信息在内部进行了共享

　　具体可以参考这篇博客 http://www.cnblogs.com/sunddenly/p/4018459.html

4. 启动 Kafka

　　由于kafka以来ZooKeeper，所以有了上面一步的ZooKeeper了解。

　　实际中，可以直接下载kafka的二进制包，直接使用，http://mirror.bit.edu.cn/apache/kafka/1.0.0/kafka_2.12-1.0.0.tgz

　　启动Zookeeper

1 ./bin/zookeeper-server-start.sh config/zookeeper.properties

　　启动Kafka

1 ./bin/kafka-server-start.sh config/server.properties

　　创建主题

1 ./bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic test

　　查看主题

1 ./bin/kafka-topics.sh --list --zookeeper localhost:2181

　　发送消息

1 ./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test

　　消费消息

1 ./bin/kafka-console-consumer.sh --zookeeper localhost:2181 --topic test --from-beginning

5. Erlang 连接 kafka

　　主要参考这个 https://github.com/msdevanms/emqttd_plugin_kafka_bridge

　　增加依赖 https://github.com/helpshift/ekaf.git

　　首先在Makefile增加

1 DEPS = eredis ecpool clique ekaf
2 dep_ekaf = git https://github.com/helpshift/ekaf master

　　然后在rebar.config 增加

1 {ekaf, “.*”, {git, “https://github.com/helpshift/ekaf”, “master”}}

　　在etc/emq_plugin_wunaozai.conf 中增加

1 ## kafka config
2 wunaozai.msg.kafka.server = 127.0.0.1:9092
3 wunaozai.msg.kafka.topic = test

　　在priv/emq_plugin_wunaozai.schema 中增加

 1 %% wunaozai.msg.kafka.server = 127.0.0.1:9092
 2 {
 3     mapping,
 4     "wunaozai.msg.kafka.server",
 5     "emq_plugin_wunaozai.kafka",
 6     [
 7         {default, {"127.0.0.1", 9092}},
 8         {datatype, [integer, ip, string]}
 9     ]
10 }.
11 
12 %% wunaozai.msg.kafka.topic = test
13 {
14     mapping,
15     "wunaozai.msg.kafka.topic",
16     "emq_plugin_wunaozai.kafka",
17     [
18         {default, "test"},
19         {datatype, string},
20         hidden
21     ]
22 }.
23 
24 %% translation
25 {
26     translation,
27     "emq_plugin_wunaozai.kafka",
28     fun(Conf) ->
29             {RHost, RPort} = case cuttlefish:conf_get("wunaozai.msg.kafka.server", Conf) of
30                                  {Ip, Port} -> {Ip, Port};
31                                  S          -> case string:tokens(S, ":") of
32                                                    [Domain]       -> {Domain, 9092};
33                                                    [Domain, Port] -> {Domain, list_to_integer(Port)}
34                                                end
35                              end,
36             Topic = cuttlefish:conf_get("wunaozai.msg.kafka.topic", Conf),
37             [
38              {host, RHost},
39              {port, RPort},
40              {topic, Topic}
41             ]
42     end
43 }.

6. 数据发往Kafka

　　接下来，由于功能基本上是基于EMQ框架的Hook钩子设计，在EMQ接收到客户端上下线、主题订阅或消息发布确认时，触发钩子顺序执行回调函数，所以大部分功能在 src/emq_plugin_wunaozai.erl 文件进行修改。

  1 -module(emq_plugin_wunaozai).
  2 
  3 -include("emq_plugin_wunaozai.hrl").
  4 
  5 -include_lib("emqttd/include/emqttd.hrl").
  6 
  7 -export([load/1, unload/0]).
  8 
  9 %% Hooks functions
 10 
 11 -export([on_client_connected/3, on_client_disconnected/3]).
 12 
 13 -export([on_client_subscribe/4, on_client_unsubscribe/4]).
 14 
 15 -export([on_session_created/3, on_session_subscribed/4, on_session_unsubscribed/4, on_session_terminated/4]).
 16 
 17 -export([on_message_publish/2, on_message_delivered/4, on_message_acked/4]).
 18 
 19 %% Called when the plugin application start
 20 load(Env) ->
 21     ekaf_init([Env]),
 22     emqttd:hook('client.connected', fun ?MODULE:on_client_connected/3, [Env]),
 23     emqttd:hook('client.disconnected', fun ?MODULE:on_client_disconnected/3, [Env]),
 24     emqttd:hook('client.subscribe', fun ?MODULE:on_client_subscribe/4, [Env]),
 25     emqttd:hook('client.unsubscribe', fun ?MODULE:on_client_unsubscribe/4, [Env]),
 26     emqttd:hook('session.created', fun ?MODULE:on_session_created/3, [Env]),
 27     emqttd:hook('session.subscribed', fun ?MODULE:on_session_subscribed/4, [Env]),
 28     emqttd:hook('session.unsubscribed', fun ?MODULE:on_session_unsubscribed/4, [Env]),
 29     emqttd:hook('session.terminated', fun ?MODULE:on_session_terminated/4, [Env]),
 30     emqttd:hook('message.publish', fun ?MODULE:on_message_publish/2, [Env]),
 31     emqttd:hook('message.delivered', fun ?MODULE:on_message_delivered/4, [Env]),
 32     emqttd:hook('message.acked', fun ?MODULE:on_message_acked/4, [Env]),
 33     io:format("start wunaozai Test Reload.~n", []).
 34 
 35 on_client_connected(ConnAck, Client = #mqtt_client{client_id = ClientId}, _Env) ->
 36     io:format("client ~s connected, connack: ~w~n", [ClientId, ConnAck]),
 37     ekaf_send(<<"connected">>, ClientId, {}, _Env),
 38     {ok, Client}.
 39 
 40 on_client_disconnected(Reason, _Client = #mqtt_client{client_id = ClientId}, _Env) ->
 41     io:format("client ~s disconnected, reason: ~w~n", [ClientId, Reason]),
 42     ekaf_send(<<"disconnected">>, ClientId, {}, _Env),
 43     ok.
 44 
 45 on_client_subscribe(ClientId, Username, TopicTable, _Env) ->
 46     io:format("client(~s/~s) will subscribe: ~p~n", [Username, ClientId, TopicTable]),
 47     {ok, TopicTable}.
 48     
 49 on_client_unsubscribe(ClientId, Username, TopicTable, _Env) ->
 50     io:format("client(~s/~s) unsubscribe ~p~n", [ClientId, Username, TopicTable]),
 51     {ok, TopicTable}.
 52 
 53 on_session_created(ClientId, Username, _Env) ->
 54     io:format("session(~s/~s) created.", [ClientId, Username]).
 55 
 56 on_session_subscribed(ClientId, Username, {Topic, Opts}, _Env) ->
 57     io:format("session(~s/~s) subscribed: ~p~n", [Username, ClientId, {Topic, Opts}]),
 58     ekaf_send(<<"subscribed">>, ClientId, {Topic, Opts}, _Env),
 59     {ok, {Topic, Opts}}.
 60 
 61 on_session_unsubscribed(ClientId, Username, {Topic, Opts}, _Env) ->
 62     io:format("session(~s/~s) unsubscribed: ~p~n", [Username, ClientId, {Topic, Opts}]),
 63     ekaf_send(<<"unsubscribed">>, ClientId, {Topic, Opts}, _Env),
 64     ok.
 65 
 66 on_session_terminated(ClientId, Username, Reason, _Env) ->
 67     io:format("session(~s/~s) terminated: ~p.~n", [ClientId, Username, Reason]),
 68     stop.
 69 
 70 %% transform message and return
 71 on_message_publish(Message = #mqtt_message{topic = <<"$SYS/", _/binary>>}, _Env) ->
 72     {ok, Message};
 73 on_message_publish(Message, _Env) ->
 74     io:format("publish ~s~n", [emqttd_message:format(Message)]),
 75     ekaf_send(<<"public">>, {}, Message, _Env),
 76     {ok, Message}.
 77 
 78 on_message_delivered(ClientId, Username, Message, _Env) ->
 79     io:format("delivered to client(~s/~s): ~s~n", [Username, ClientId, emqttd_message:format(Message)]),
 80     {ok, Message}.
 81 
 82 on_message_acked(ClientId, Username, Message, _Env) ->
 83     io:format("client(~s/~s) acked: ~s~n", [Username, ClientId, emqttd_message:format(Message)]),
 84     {ok, Message}.
 85 
 86 %% Called when the plugin application stop
 87 unload() ->
 88     emqttd:unhook('client.connected', fun ?MODULE:on_client_connected/3),
 89     emqttd:unhook('client.disconnected', fun ?MODULE:on_client_disconnected/3),
 90     emqttd:unhook('client.subscribe', fun ?MODULE:on_client_subscribe/4),
 91     emqttd:unhook('client.unsubscribe', fun ?MODULE:on_client_unsubscribe/4),
 92     emqttd:unhook('session.created', fun ?MODULE:on_session_created/3),
 93     emqttd:unhook('session.subscribed', fun ?MODULE:on_session_subscribed/4),
 94     emqttd:unhook('session.unsubscribed', fun ?MODULE:on_session_unsubscribed/4),
 95     emqttd:unhook('session.terminated', fun ?MODULE:on_session_terminated/4),
 96     emqttd:unhook('message.publish', fun ?MODULE:on_message_publish/2),
 97     emqttd:unhook('message.delivered', fun ?MODULE:on_message_delivered/4),
 98     emqttd:unhook('message.acked', fun ?MODULE:on_message_acked/4).
 99 
100 %% ==================== ekaf_init STA.===============================%%
101 ekaf_init(_Env) ->
102     % clique 方式读取配置文件
103     Env = application:get_env(?APP, kafka),
104     {ok, Kafka} = Env,
105     Host = proplists:get_value(host, Kafka),
106     Port = proplists:get_value(port, Kafka),
107     Broker = {Host, Port},
108     Topic = proplists:get_value(topic, Kafka),
109     io:format("~w ~w ~w ~n", [Host, Port, Topic]),
110 
111     % init kafka
112     application:set_env(ekaf, ekaf_partition_strategy, strict_round_robin),
113     application:set_env(ekaf, ekaf_bootstrap_broker, Broker),
114     application:set_env(ekaf, ekaf_bootstrap_topics, list_to_binary(Topic)),
115     %application:set_env(ekaf, ekaf_bootstrap_broker, {"127.0.0.1", 9092}),
116     %application:set_env(ekaf, ekaf_bootstrap_topics, <<"test">>),
117 
118     %io:format("Init ekaf with ~s:~b~n", [Host, Port]),
119     %%ekaf:produce_async_batched(<<"test">>, list_to_binary(Json)),
120     ok.
121 %% ==================== ekaf_init END.===============================%%
122 
123 
124 %% ==================== ekaf_send STA.===============================%%
125 ekaf_send(Type, ClientId, {}, _Env) ->
126     Json = mochijson2:encode([
127                               {type, Type},
128                               {client_id, ClientId},
129                               {message, {}},
130                               {cluster_node, node()},
131                               {ts, emqttd_time:now_ms()}
132                              ]),
133     ekaf_send_sync(Json);
134 ekaf_send(Type, ClientId, {Reason}, _Env) ->
135     Json = mochijson2:encode([
136                               {type, Type},
137                               {client_id, ClientId},
138                               {cluster_node, node()},
139                               {message, Reason},
140                               {ts, emqttd_time:now_ms()}
141                              ]),
142     ekaf_send_sync(Json);
143 ekaf_send(Type, ClientId, {Topic, Opts}, _Env) ->
144     Json = mochijson2:encode([
145                               {type, Type},
146                               {client_id, ClientId},
147                               {cluster_node, node()},
148                               {message, [
149                                          {topic, Topic},
150                                          {opts, Opts}
151                                         ]},
152                               {ts, emqttd_time:now_ms()}
153                              ]),
154     ekaf_send_sync(Json);
155 ekaf_send(Type, _, Message, _Env) ->
156     Id = Message#mqtt_message.id,
157     From = Message#mqtt_message.from, %需要登录和不需要登录这里的返回值是不一样的
158     Topic = Message#mqtt_message.topic,
159     Payload = Message#mqtt_message.payload,
160     Qos = Message#mqtt_message.qos,
161     Dup = Message#mqtt_message.dup,
162     Retain = Message#mqtt_message.retain,
163     Timestamp = Message#mqtt_message.timestamp,
164 
165     ClientId = c(From),
166     Username = u(From),
167 
168     Json = mochijson2:encode([
169                               {type, Type},
170                               {client_id, ClientId},
171                               {message, [
172                                          {username, Username},
173                                          {topic, Topic},
174                                          {payload, Payload},
175                                          {qos, i(Qos)},
176                                          {dup, i(Dup)},
177                                          {retain, i(Retain)}
178                                         ]},
179                               {cluster_node, node()},
180                               {ts, emqttd_time:now_ms()}
181                              ]),
182     ekaf_send_sync(Json).
183 
184 ekaf_send_async(Msg) ->
185     Topic = ekaf_get_topic(),
186     ekaf_send_async(Topic, Msg).
187 ekaf_send_async(Topic, Msg) ->
188     ekaf:produce_async_batched(list_to_binary(Topic), list_to_binary(Msg)).
189 ekaf_send_sync(Msg) ->
190     Topic = ekaf_get_topic(),
191     ekaf_send_sync(Topic, Msg).
192 ekaf_send_sync(Topic, Msg) ->
193     ekaf:produce_sync_batched(list_to_binary(Topic), list_to_binary(Msg)).
194 
195 i(true) -> 1;
196 i(false) -> 0;
197 i(I) when is_integer(I) -> I.
198 c({ClientId, Username}) -> ClientId;
199 c(From) -> From.
200 u({ClientId, Username}) -> Username;
201 u(From) -> From.
202 %% ==================== ekaf_send END.===============================%%
203 
204 
205 %% ==================== ekaf_set_host STA.===============================%%
206 ekaf_set_host(Host) ->
207     ekaf_set_host(Host, 9092).
208 ekaf_set_host(Host, Port) ->
209     Broker = {Host, Port},
210     application:set_env(ekaf, ekaf_bootstrap_broker, Broker),
211     io:format("reset ekaf Broker ~s:~b ~n", [Host, Port]),
212     ok.
213 %% ==================== ekaf_set_host END.===============================%%
214 
215 %% ==================== ekaf_set_topic STA.===============================%%
216 ekaf_set_topic(Topic) ->
217     application:set_env(ekaf, ekaf_bootstrap_topics, list_to_binary(Topic)),
218     ok.
219 ekaf_get_topic() ->
220     Env = application:get_env(?APP, kafka),
221     {ok, Kafka} = Env,
222     Topic = proplists:get_value(topic, Kafka),
223     Topic.
224 %% ==================== ekaf_set_topic END.===============================%%

　　上面是所有源代码，下面对其进行简单说明

　　ekaf_init 函数，主要对配置文件的读取和解析并存放到application的环境变量中

　　ekaf_send 函数，主要是封装成对应的JSON数据，然后发到Kafka中

　　ekaf_send_async 函数，主要是异步发送JSON数据，不确保发往Kafka的顺序与Kafka消费者的接收时的顺序

　　ekaf_send_sync 函数，是同步发送JSON数据，确保按照顺序发往kafka与Kafka消费者有序接收数据

　　ekaf_set_host 函数，设置kafka的域名与端口

　　ekaf_set_topic 函数，设置发往kafka时的主题

　　ekaf_get_topic 函数，获取当前主题

　　load函数增加ekaf_init调用

　　剩下的在每个钩子回调中调用 ekaf_send函数

7. 测试

　　（1）启动Zookeeper ./bin/zookeeper-server-start.sh config/zookeeper.properties

　　（2）启动Kafka ./bin/kafka-server-start.sh config/server.properties

　　（3）启动消费者 ./bin/kafka-console-consumer.sh --zookeeper localhost:2181 --topic test --from-beginning

　　（4）启动一个生产者 ./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test

　　（5）启动EMQ ./_rel/emqttd/bin/emqttd console

　　（6）打开MQTT客户端并连接、订阅、发布等操作

　　（7）可以在消费者界面上看到获取到的信息

8. 插件源码

　　最后给出本次插件开发的所有源码

　　https://files.cnblogs.com/files/wunaozai/emq_plugin_wunaozai.zip

查看全文

相关阅读:
最长递增长度（最长上升子序列）
完全背包问题
 vue中使用el-tabs组件遇到的问题
 ORACLE中排序的时候空值处理
 ORA-01089数据库无法正常关闭
 Oracle中的LPAD和RPAD的使用
 Oracle中Translate函数的使用
 通过对照表快速建view
Oracle数据库create or replace
打字网站

原文地址：https://www.cnblogs.com/wunaozai/p/8249657.html