MQTT.js is a client library for the MQTT protocol, written in JavaScript for node.js and the browser.
MQTT.js is an OPEN Open Source Project, see the Contributing section to find out what this means.
v1.0.0 improves the overall architecture of the project, which is now split into three components: MQTT.js keeps the Client, mqtt-connection includes the barebone Connection code for server-side usage, and mqtt-packet includes the protocol parser and generator. The new Client improves performance by a 30% factor, embeds Websocket support (MOWS is now deprecated), and it has a better support for QoS 1 and 2. The previous API is still supported but deprecated, as such, it id not documented in this README.
As a breaking change, the encoding
option in the old client is
removed, and now everything is UTF-8 with the exception of the
password
in the CONNECT message and payload
in the PUBLISH message,
which are Buffer
.
Another breaking change is that MQTT.js now defaults to MQTT v3.1.1, so to support old brokers, please read the client options doc.
npm install mqtt --save
For the sake of simplicity, let's put the subscriber and the publisher in the same file:
var mqtt = require('mqtt');
var client = mqtt.connect('mqtt://test.mosquitto.org');
client.on('connect', function () {
client.subscribe('presence');
client.publish('presence', 'Hello mqtt');
});
client.on('message', function (topic, message) {
// message is Buffer
console.log(message.toString());
client.end();
});
output:
Hello mqtt
If you want to run your own MQTT broker, you can use Mosquitto or Mosca, and launch it. You can also use a test instance: test.mosquitto.org and test.mosca.io are both public.
If you do not want to install a separate broker, you can try using the server/orig example. It implements enough of the semantics of the MQTT protocol to run the example.
to use MQTT.js in the browser see the browserify section
MQTT.js bundles a command to interact with a broker. In order to have it available on your path, you should install MQTT.js globally:
npm install mqtt -g
Then, on one terminal
mqtt sub -t 'hello' -h 'test.mosquitto.org' -v
On another
mqtt pub -t 'hello' -h 'test.mosquitto.org' -m 'from MQTT.js'
See mqtt help <command>
for the command help.
mqtt.connect()
mqtt.Client()
mqtt.Client#publish()
mqtt.Client#subscribe()
mqtt.Client#unsubscribe()
mqtt.Client#end()
mqtt.Client#handleMessage()
mqtt.Store()
mqtt.Store#put()
mqtt.Store#del()
mqtt.Store#createStream()
mqtt.Store#close()
Connects to the broker specified by the given url and options and returns a Client.
The URL can be on the following protocols: 'mqtt', 'mqtts', 'tcp',
'tls', 'ws', 'wss'. The URL can also be an object as returned by
URL.parse()
,
in that case the two objects are merged, i.e. you can pass a single
object with both the URL and the connect options.
You can also specify a servers
options with content: [{ host: 'localhost', port: 1883 }, ... ]
, in that case that array is iterated
at every connect.
For all MQTT-related options, see the Client constructor.
The Client
class wraps a client connection to an
MQTT broker over an arbitrary transport method (TCP, TLS,
WebSocket, ecc).
Client
automatically handles the following:
- Regular server pings
- QoS flow
- Automatic reconnections
- Start publishing before being connected
The arguments are:
streamBuilder
is a function that returns a subclass of theStream
class that supports theconnect
event. Typically anet.Socket
.options
is the client connection options (see: the connect packet). Defaults:keepalive
:10
seconds, set to0
to disableclientId
:'mqttjs_' + Math.random().toString(16).substr(2, 8)
protocolId
:'MQTT'
protocolVersion
:4
clean
:true
, set to false to receive QoS 1 and 2 messages while offlinereconnectPeriod
:1000
milliseconds, interval between two reconnectionsconnectTimeout
:30 * 1000
milliseconds, time to wait before a CONNACK is receivedusername
: the username required by your broker, if anypassword
: the password required by your broker, if anyincomingStore
: a Store for the incoming packetsoutgoingStore
: a Store for the outgoing packetswill
: a message that will sent by the broker automatically when the client disconnect badly. The format is:topic
: the topic to publishpayload
: the message to publishqos
: the QoSretain
: the retain flag
In case mqtts (mqtt over tls) is required, the options
object is
passed through to
tls.connect()
.
If you are using a self-signed certificate, pass the rejectUnauthorized: false
option.
Beware that you are exposing yourself to man in the middle attacks, so it is a configuration
that is not recommended for production environments.
If you are connecting to a broker that supports only MQTT 3.1 (not 3.1.1 compliant), you should pass these additional options:
{
protocolId: 'MQIsdp',
protocolVersion: 3
}
This is confirmed on RabbitMQ 3.2.4, and on Mosquitto < 1.3. Mosquitto version 1.3 and 1.4 works fine without those.
function(connack) {}
Emitted on successful (re)connection (i.e. connack rc=0).
connack
received connack packet. Whenclean
connection option isfalse
and server has a previous session forclientId
connection option, thenconnack.sessionPresent
flag istrue
. When that is the case, you may rely on stored session and prefer not to send subscribe commands for the client.
function() {}
Emitted when a reconnect starts.
function() {}
Emitted after a disconnection.
function() {}
Emitted when the client goes offline.
function(error) {}
Emitted when the client cannot connect (i.e. connack rc != 0) or when a parsing error occurs.
function(topic, message, packet) {}
Emitted when the client receives a publish packet
topic
topic of the received packetmessage
payload of the received packetpacket
received packet, as defined in mqtt-packet
Publish a message to a topic
topic
is the topic to publish to,String
message
is the message to publish,Buffer
orString
options
is the options to publish with, including:qos
QoS level,Number
, default0
retain
retain flag,Boolean
, defaultfalse
callback
callback fired when the QoS handling completes, or at the next tick if QoS 0.
Subscribe to a topic or topics
topic
is aString
topic to subscribe to or anArray
of topics to subscribe to. It can also be an object, it has as object keys the topic name and as value the QoS, like{'test1': 0, 'test2': 1}
.options
is the options to subscribe with, including:qos
qos subscription level, default 0
callback
-function(err, granted)
callback fired on suback where:err
a subscription errorgranted
is an array of{topic, qos}
where:topic
is a subscribed to topicqos
is the granted qos level on it
Unsubscribe from a topic or topics
topic
is aString
topic or an array of topics to unsubscribe fromcallback
fired on unsuback
Close the client, accepts the following options:
force
: passing it to true will close the client right away, without waiting for the in-flight messages to be acked. This parameter is optional.cb
: will be called when the client is closed. This parameter is optional.
Handle messages with backpressure support, one at a time.
Override at will, but always call callback
, or the client
will hang.
In-memory implementation of the message store.
Another implementaion is mqtt-level-store which uses Level-browserify to store the inflight data, making it usable both in Node and the Browser.
Adds a packet to the store, a packet is
anything that has a messageId
property.
The callback is called when the packet has been stored.
Creates a stream with all the packets in the store.
Removes a packet from the store, a packet is
anything that has a messageId
property.
The callback is called when the packet has been removed.
Closes the Store.
In order to use MQTT.js as a browserify module you can either require it in your browserify bundles or build it as a stand alone module. The exported module is AMD/CommonJs compatible and it will add an object in the global space.
npm install -g browserify // install browserify
cd node_modules/mqtt
npm install . // install dev dependencies
browserify mqtt.js -s mqtt > browserMqtt.js // require mqtt in your client-side app
Just like browserify, export MQTT.js as library. The exported module would be var mqtt = xxx
and it will add an object in the global space. You could also export module in other formats (AMD/CommonJS/others) by setting output.libraryTarget in webpack configuration.
npm install -g webpack // install webpack
cd node_modules/mqtt
npm install . // install dev dependencies
webpack mqtt.js ./browserMqtt.js --output-library mqtt
you can then use mqtt.js in the browser with the same api than node's one.
<html>
<head>
<title>test Ws mqtt.js</title>
</head>
<body>
<script src="./browserMqtt.js"></script>
<script>
var client = mqtt.connect(); // you add a ws:// url here
client.subscribe("mqtt/demo");
client.on("message", function(topic, payload) {
alert([topic, payload].join(": "));
client.end();
});
client.publish("mqtt/demo", "hello world!");
</script>
</body>
</html>
Your broker should accept websocket connection (see MQTT over Websockets to setup Mosca).
MQTT.js is an OPEN Open Source Project. This means that:
Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.
See the CONTRIBUTING.md file for more details.
MQTT.js is only possible due to the excellent work of the following contributors:
Adam Rudd | GitHub/adamvr | Twitter/@adam_vr |
---|---|---|
Matteo Collina | GitHub/mcollina | Twitter/@matteocollina |
MIT