154 lines
4.3 KiB
Markdown
154 lines
4.3 KiB
Markdown
# MQTT Module
|
|
|
|
The client adheres to version 3.1.1 of the [MQTT](https://en.wikipedia.org/wiki/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.
|
|
|
|
#### 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
|
|
```lua
|
|
-- init mqtt client with 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", 1880, 0, function(client) print("connected") 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
|
|
`nil`
|
|
|
|
## 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)])`
|
|
|
|
#### Parameters
|
|
- `host` host, domain or IP (string)
|
|
- `port` broker port (number), default 1883
|
|
- `secure` 0/1 for `false`/`true`, default 0. [As per #539](https://github.com/nodemcu/nodemcu-firmware/issues/539#issuecomment-170298120) secure connections use TLS 1.2.
|
|
- `autoreconnect` 0/1 for `false`/`true`, default 0
|
|
- `function(client)` call back function for when the connection was established
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
## mqtt.client:lwt()
|
|
|
|
Setup [Last Will and Testament](http://www.hivemq.com/blog/mqtt-essentials-part-9-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](http://www.hivemq.com/blog/mqtt-essentials-part-5-mqtt-topics-best-practices))
|
|
- `message` the message to publish, (buffer or string)
|
|
- `qos` QoS level
|
|
- `retain` retain flag
|
|
- `function(client)` optional callback fired when PUBACK received
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
## mqtt.client:subscribe()
|
|
|
|
Subscribes to one or several topics.
|
|
|
|
#### Syntax
|
|
`mqtt:subscribe(topic, qos[, function(client, topic, message)])`
|
|
|
|
#### Parameters
|
|
- `topic` a [topic string](http://www.hivemq.com/blog/mqtt-essentials-part-5-mqtt-topics-best-practices)
|
|
- `qos` QoS subscription level, default 0
|
|
- `function(client, topic, message)` optional callback fired when message received
|
|
|
|
#### Returns
|
|
`nil`
|