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NodeMCU文档中文翻译 6 MQTT模块

2017-09-19 11:11 405 查看

一、译文

MQTT客户端支持Mqtt3.1.1协议，要确保你的MQTT服务器配置正确并支持3.1.1版本。此Mqtt模块并不兼容3.1版本之前的MQTT服务器。

mqtt.Client()	创建一个MQTT客户端.
mqtt.client:close()	关闭与服务器之间的连接.
mqtt.client:connect()	根据主机名、端口号和安全配置连接服务器.
mqtt.client:lwt()	创建遗嘱 (可选).
mqtt.client:on()	为事件创建回调函数.
mqtt.client:publish()	发送一条消息.
mqtt.client:subscribe()	订阅一个或多个主题.
mqtt.client:unsubscribe()	取消订阅一个或多个主题.

1、mqtt.Client()

创建一个MQTT客户端。

语法(PS:中括号内为可选参数)

mqtt.Client(clientid, keepalive[, username, password, cleansession])

参数

clientid

客户端id

keepalive

心跳秒数

username

用户名

password

密码

cleansession

清除session
0/1 表示

否

是

返回

Mqtt客户端

示例代码

[javascript] view
plain copy

-- 初始化无需登陆的客户端, 心跳时间 120秒

m = mqtt.Client("clientid", 120)



-- 初始化需要登陆的客户端, 心跳时间 120秒

m = mqtt.Client("clientid", 120, "user", "password")



-- 创建遗嘱(可选)

-- 服务器将会发送一条 qos = 0, retain = 0, 内容为"offline"的消息到"/lwt"主题，如果没收到客户端发送的心跳数据包(掉线)

m:lwt("/lwt", "offline", 0, 0)



m:on("connect", function(client) print ("connected") end) --连接到服务器触发事件

m:on("offline", function(client) print ("offline") end) --掉线触发事件



-- 收到消息时触发事件

m:on("message", function(client, topic, data)

  print(topic .. ":" )

  if data ~= nil then

    print(data)

  end

end)



-- 对于 TLS: m:connect("192.168.11.118", secure-port, 1)

m:connect("192.168.11.118", 1883, 0, function(client) print("connected") end,

                                     function(client, reason) print("failed reason: "..reason) end)



-- 确保subscribe/publish方法在连接上服务器后再调用，在实际应用中是把他们放在connect回调函数里或者确定连接成功



-- 订阅/topic主题、服务质量为0

m:subscribe("/topic",0, function(client) print("subscribe success") end)

-- 发送一条信息 data = hello, QoS = 0, retain = 0

m:publish("/topic","hello",0,0, function(client) print("sent") end)



m:close();

-- 你可以再次调用 m:connect 连接函数

2、mqtt.client:close()

关闭与服务器的连接

语法 mqtt:close()
参数无

返回成功true，失败false

3、mqtt.client:connect()

根据主机名、端口号和安全配置连接服务器。

语法
mqtt:connect(host[, port[, secure[, autoreconnect]]][, function(client)[, function(client, reason)]])
参数

host

主机名,
域名或 IP (字符串)

port

服务器端口(数字),
默认1883

secure

0/1
表示

false

true

,
默认 0. 详情查看文档 net module.

autoreconnect

0/1表示

false

true

,默认
0 (断线是否重连)

function(client)

连接服务器成功时的回调函数

function(client,
reason)

连接服务器失败时的回调函数

返回
成功true，失败false

连接失败时的错误代码


常量	值	描述
mqtt.CONN_FAIL_SERVER_NOT_FOUND	-5	未找到服务器(或没开端口)
mqtt.CONN_FAIL_NOT_A_CONNACK_MSG	-4	返回消息回应不是Mqtt协议
mqtt.CONN_FAIL_DNS	-3	DNS错误
mqtt.CONN_FAIL_TIMEOUT_RECEIVING	-2	等待响应超时
mqtt.CONN_FAIL_TIMEOUT_SENDING	-1	尝试发送连接消息超时
mqtt.CONNACK_ACCEPTED	0	没有错误. 注意: 这不会触发错误回调函数.
mqtt.CONNACK_REFUSED_PROTOCOL_VER	1	服务器MQTT版本不是3.1.1.
mqtt.CONNACK_REFUSED_ID_REJECTED	2	ClientID被服务器拒绝. (查看 mqtt.Client() )
mqtt.CONNACK_REFUSED_SERVER_UNAVAILABLE	3	服务不可用.
mqtt.CONNACK_REFUSED_BAD_USER_OR_PASS	4	用户名或密码错误.
mqtt.CONNACK_REFUSED_NOT_AUTHORIZED	5	用户名没经过认证.

4、mqtt.client:lwt()

创建遗嘱(可选)，服务器将会发送一条 qos = 0, retain = 0, 内容为"offline"的消息到"/lwt"主题，如果没收到客户端发送的心跳数据包(掉线)。

语法
mqtt:lwt(topic, message[, qos[, retain]])

参数

topic

将要发送遗嘱消息的主题
(字符串)

message

遗嘱消息,
(缓存或字符串)

qos

消息质量,
默认 0

retain

保留标志,
默认 0
返回空

5、mqtt.client:on()

为事件创建回调函数.

语法
mqtt:on(event, function(client[, topic[, message]]))

参数

event

可以是
"connect", "message" 或者 "offline"

function(client[,
topic[, message]])

回调函数。第一个参数为client、如果事件为 "message"，那么第二个、第三个参数分别是主题和接收到的消息

返回空

6、mqtt.client:publish()

发送一条消息.

语法
mqtt:publish(topic, payload, qos, retain[, function(client)])

参数

topic

要发送消息的主题
(字符串)

message

消息,
(缓存或字符串)

qos

消息质量

retain

消息保留标志

function(client)

可选的回调函数。当消息发送成功(服务器传来PUBACK响应)则触发该事件。注意:当多次调用publish()
函数，所有的发送指令将会调用最后定义的回调函数。

返回
成功true，失败false

7、mqtt.client:subscribe()

订阅一个或多个主题.

语法

mqtt:subscribe(topic,
qos[, function(client)]) 或

mqtt:subscribe(table[,
function(client)])

参数

topic

主题
(字符串)

qos

订阅的消息质量,
默认 0

table

要订阅的'topic,
qos'数组对

function(client)

订阅成功时的可选回调函数.注意:当多次调用subscribe()
函数，所有的订阅指令将会调用最后定义的回调函数。

返回
成功true，失败false

示例代码

[javascript] view
plain copy

-- 订阅/topic主题、服务质量为0

m:subscribe("/topic",0, function(conn) print("subscribe success") end)



-- 或者订阅多个主题 (topic/0, qos = 0; topic/1, qos = 1; topic2 , qos = 2)

m:subscribe({["topic/0"]=0,["topic/1"]=1,topic2=2}, function(conn) print("subscribe success") end)

8、mqtt.client:unsubscribe()

取消订阅一个或多个主题.

语法

mqtt:unsubscribe(topic[,
function(client)]) 或

mqtt:unsubscribe(table[,
function(client)])

参数

topic

主题
(字符串)

table

要取消订阅的'topic,
qos'数组对

function(client)

取消订阅成功时的可选回调函数.注意:当多次调用unsubscribe()
函数，所有的取消订阅指令将会调用最后定义的回调函数。

返回
成功true，失败false

示例代码

[javascript] view
plain copy

-- 取消订阅主题

m:unsubscribe("/topic", function(conn) print("unsubscribe success") end)



-- 或者取消订阅多个主题 (topic/0; topic/1; topic2)

m:unsubscribe({["topic/0"]=0,["topic/1"]=0,topic2="anything"}, function(conn) print("unsubscribe success") end)

【转载请注明出处:http://blog.csdn.net/leytton/article/details/72454287】

二、原文

摘自https://nodemcu.readthedocs.io/en/master/en/modules/mqtt/

MQTT Module


Since	Origin / Contributor	Maintainer	Source
2015-01-23	Stephen Robinson, Tuan PM	Vowstar	mqtt.c

The client adheres to version 3.1.1 of the MQTT protocol. Make sure that your broker supports and is correctly configured for
version 3.1.1. The client is backwards incompatible with brokers running MQTT 3.1.

mqtt.Client()	Creates a MQTT client.
mqtt.client:close()	Closes connection to the broker.
mqtt.client:connect()	Connects to the broker specified by the given host, port, and secure options.
mqtt.client:lwt()	Setup Last Will and Testament (optional).
mqtt.client:on()	Registers a callback function for an event.
mqtt.client:publish()	Publishes a message.
mqtt.client:subscribe()	Subscribes to one or several topics.
mqtt.client:unsubscribe()	Unsubscribes from one or several topics.

mqtt.Client()

Creates a MQTT client.

Syntax

mqtt.Client(clientid,
keepalive[, username, password, cleansession])

Parameters

clientid

client
ID

keepalive

keepalive
seconds

username

user
name

password

user
password

cleansession

0/1
for

false

true

Returns

MQTT client

Example

-- init mqtt client without logins, keepalive timer 120s
m = mqtt.Client("clientid", 120)

-- init mqtt client with logins, keepalive timer 120sec
m = mqtt.Client("clientid", 120, "user", "password")

-- setup Last Will and Testament (optional)
-- Broker will publish a message with qos = 0, retain = 0, data = "offline"
-- to topic "/lwt" if client don't send keepalive packet
m:lwt("/lwt", "offline", 0, 0)

m:on("connect", function(client) print ("connected") end)
m:on("offline", function(client) print ("offline") end)

-- on publish message receive event
m:on("message", function(client, topic, data)
print(topic .. ":" )
if data ~= nil then
print(data)
end
end)

-- for TLS: m:connect("192.168.11.118", secure-port, 1)
m:connect("192.168.11.118", 1883, 0, function(client) print("connected") end,
function(client, reason) print("failed reason: "..reason) end)

-- Calling subscribe/publish only makes sense once the connection
-- was successfully established. In a real-world application you want
-- move those into the 'connect' callback or make otherwise sure the
-- connection was established.

-- subscribe topic with qos = 0
m:subscribe("/topic",0, function(client) print("subscribe success") end)
-- publish a message with data = hello, QoS = 0, retain = 0
m:publish("/topic","hello",0,0, function(client) print("sent") end)

m:close();
-- you can call m:connect again

MQTT Client

mqtt.client:close()

Closes connection to the broker.

Syntax

mqtt:close()

Parameters

none

Returns

true

on
success,

false

otherwise

mqtt.client:connect()

Connects to the broker specified by the given host, port, and secure options.

Syntax

mqtt:connect(host[,
port[, secure[, autoreconnect]]][, function(client)[, function(client, reason)]])

Parameters

host

host,
domain or IP (string)

port

broker
port (number), default 1883

secure

0/1
for

false

true

,
default 0. Take note of constraints documented in the net module.

autoreconnect

0/1
for

false

true

,
default 0

function(client)

callback
function for when the connection was established

function(client,
reason)

callback function for when the connection could not be established

Returns

true

on
success,

false

otherwise

Connection failure callback reason codes:


Constant	Value	Description
mqtt.CONN_FAIL_SERVER_NOT_FOUND	-5	There is no broker listening at the specified IP Address and Port
mqtt.CONN_FAIL_NOT_A_CONNACK_MSG	-4	The response from the broker was not a CONNACK as required by the protocol
mqtt.CONN_FAIL_DNS	-3	DNS Lookup failed
mqtt.CONN_FAIL_TIMEOUT_RECEIVING	-2	Timeout waiting for a CONNACK from the broker
mqtt.CONN_FAIL_TIMEOUT_SENDING	-1	Timeout trying to send the Connect message
mqtt.CONNACK_ACCEPTED	0	No errors. Note: This will not trigger a failure callback.
mqtt.CONNACK_REFUSED_PROTOCOL_VER	1	The broker is not a 3.1.1 MQTT broker.
mqtt.CONNACK_REFUSED_ID_REJECTED	2	The specified ClientID was rejected by the broker. (See mqtt.Client() )
mqtt.CONNACK_REFUSED_SERVER_UNAVAILABLE	3	The server is unavailable.
mqtt.CONNACK_REFUSED_BAD_USER_OR_PASS	4	The broker refused the specified username or password.
mqtt.CONNACK_REFUSED_NOT_AUTHORIZED	5	The username is not authorized.

mqtt.client:lwt()

Setup Last Will and Testament (optional). A broker will publish a message with qos =
0, retain = 0, data = "offline" to topic "/lwt" if client does not send keepalive packet.

Syntax

mqtt:lwt(topic,
message[, qos[, retain]])

Parameters

topic

the
topic to publish to (string)

message

the
message to publish, (buffer or string)

qos

QoS
level, default 0

retain

retain
flag, default 0

Returns

nil

mqtt.client:on()

Registers a callback function for an event.

Syntax

mqtt:on(event,
function(client[, topic[, message]]))

Parameters

event

can
be "connect", "message" or "offline"

function(client[,
topic[, message]])

callback function. The first parameter is the client. If event is "message", the 2nd and 3rd param are received topic and message (strings).

Returns

nil

mqtt.client:publish()

Publishes a message.

Syntax

mqtt:publish(topic,
payload, qos, retain[, function(client)])

Parameters

topic

the
topic to publish to (topic string)

message

the
message to publish, (buffer or string)

qos

QoS
level

retain

retain
flag

function(client)

optional
callback fired when PUBACK received. NOTE: When calling publish() more than once, the last callback function defined will be called for ALL publish commands.

Returns

true

on
success,

false

otherwise

mqtt.client:subscribe()

Subscribes to one or several topics.

Syntax

mqtt:subscribe(topic,
qos[, function(client)])

mqtt:subscribe(table[,
function(client)])

Parameters

topic

a topic
string

qos

QoS
subscription level, default 0

table

array
of 'topic, qos' pairs to subscribe to

function(client)

optional
callback fired when subscription(s) succeeded. NOTE: When calling subscribe() more than once, the last callback function defined will be called for ALL subscribe commands.

Returns

true

on
success,

false

otherwise

Example

-- subscribe topic with qos = 0
m:subscribe("/topic",0, function(conn) print("subscribe success") end)

-- or subscribe multiple topic (topic/0, qos = 0; topic/1, qos = 1; topic2 , qos = 2)
m:subscribe({["topic/0"]=0,["topic/1"]=1,topic2=2}, function(conn) print("subscribe success") end)

mqtt.client:unsubscribe()

Unsubscribes from one or several topics.

Syntax

mqtt:unsubscribe(topic[,
function(client)])

mqtt:unsubscribe(table[,
function(client)])

Parameters

topic

a topic
string

table

array
of 'topic, anything' pairs to unsubscribe from

function(client)

optional
callback fired when unsubscription(s) succeeded. NOTE: When calling unsubscribe() more than once, the last callback function defined will be called for ALL unsubscribe commands.

Returns

true

on
success,

false

otherwise

Example

-- unsubscribe topic
m:unsubscribe("/topic", function(conn) print("unsubscribe success") end)

-- or unsubscribe multiple topic (topic/0; topic/1; topic2)
m:unsubscribe({["topic/0"]=0,["topic/1"]=0,topic2="anything"}, function(conn) print("unsubscribe success") end)

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