Mqtt-reqres NPM

mqtt-reqres

mqtt request/response client based on mqttjs

API

Stability: Experimental

Methods

MqttReqRes(options)

constructor

options:

brokerProtocol string optional default 'mqtt' ('ws')
brokerHostname string optional default 'localhost'
brokerPort number optional default 1883
clientId string optional default random string

returns instance of MqttReqRes

Example:

var client = new MqttReqRes({
  brokerProtocol: 'mqtt',
  brokerHostname: '127.0.0.1',
  brokerPort: 9999,
  clientId: 'client-a'
})

request(toClientId, payload, meta)

send a request to an other client.

toClientId string, required. the receiver's client id

payload string|object|Buffer, optional. the message string or object to be sent. for Buffer type see Node docs

meta object, optional. an object to be sent additionaly.

returns Promise which resolves to object response

Example:

clientA.request('client-b', 'hello!', {foo: 'bar'})
  .then(function (response) {

    /* called when received response 
    response.type -> 'string', 'Buffer', 'JSON'
    response.payload -> typeof string, Buffer or Object
    */
  })
  .catch(function (reason) {
    // request failed
    console.error(reason);
  });

onRequest(callback)

defines a request handler callback function. The handler function is called internally on each request received from connected client.

callback function required; callback takes these arguments:

object req the request object with properties object connection, string topic, string type, string|object|Buffer payload and object meta
object res the response object with function send()

use res.send(message, meta) to respond to the request with string|object message and optional meta data object.

Examples:

respond with string "foo":

clientB.onRequest(function (req, res) {

  /* called when received request 
  req.type -> the payload data type 'string', 'Buffer', 'JSON'
  req.payload -> typeof string, Buffer or Object
  req.connection -> connection object
  req.topic -> string mqtt topic
  req.meta -> null|object meta object data
  */

  res.send('foo', {bar: 'baz'});
});

respond with object

clientB.onRequest(function (req, res) {

  var o = {foo: 'bar'};
  res.send(o);
});

respond with file content

clientB.onRequest(function (req, res) {

  var bufferRespond = fs.readFileSync('filename');

  res.send(bufferRespond);
});

sharedSecret(callback)

defines a connection-specific callback function to retrieve the shared secret required to connect. The callback function will be called internally on incoming as well as outgoing connection requests.

callback function required; first argument clientId is the connecting client id or the id of client to connect, the second cb a callback that takes the shared secret or falsy when connection should be refused.

function onSharedSecret (clientId, cb) {
  if (clientId === 'client-b') {
    // continue connecting with client b using shared secret
    cb('shared-secret-a-b');
  }
  else {
    // refuse connect
    cb();
  }
}

clientA.sharedSecret(onSharedSecret);

connect([toClientId, sharedSecret])

connect to broker or client with toClientId set.

toClientId string, optional. if set, connects to a client with the specified id. if omitted only connects to the broker.

sharedSecret string optional. if set it is used as the shared secret when connecting the client

Example:

clientB.sharedSecret(function (clientId, callback) {
  if (clientId === 'client-a') {
    callback('shared-secret-a-b')
  }
  else {
    callback(null);
  }
});

// connect client-b to broker
clientB.connect()
  .then(..);

..

// connect client-a to client-b
clientA.connect('client-b', 'shared-secret-a-b')
  .then(function () {
    // called when client-b is connected
  })
  .catch(function (reason) {
    // connect to client-b failed
    console.error(reason);
  });

ping(toClientId)

send ping request to client. if not yet connected, connects to client.

toClientId string, optional. if set, connects to a client with the specified id. if omitted only connects to the broker.

returns Promise resolved, when ping-ack was received, reject on timeout.

disconnect(fromClientId)

disconnect from broker or client with toClientId set.

fromClientId string, optional. if set, disconnects from a client with the specified id. if omitted, completely disconnects also also from the broker.

Example:

// completely disconnect client-b
clientB.disconnect()
  .then(..);

..

// disconnect from client-b only
clientA.disconnect('client-b')
  .then(..)

Events

broker.connect

fired when client connects to broker

client.connect

fired when a client connects

Arguments:

string clientId the client id of the connected client

Example:

client.on('client.connect', function (clientId) {
  log('on.client.connect ' + clientId);
});

include client into web page

<script src="../build/mqtt-reqres-browser.js"></script>

// or minified

<script src="../build/mqtt-reqres-browser.min.js"></script>

..

<script type="text/javascript">
  
  client = new MqttReqRes();
  ..  
</script>

use the client as a module

requires node >= 5.10.0

var MqttReqRes = require('mqtt-reqres');

test

runs mocha specs in /test

$ npm test
// or
$ npm run test:debug

you may also open test/index.html in browser to play around with a client live frontend - this requires to have a websocket mqtt broker running (mqtt-reqres-broker):

$ npm run broker

// start broker with options
$ npm run broker -- -h 127.0.0.1 -p 9999

other tasks

// build all
$ npm run build

// create build/mqtt-reqres-browser.js
$ npm run browserify

// create annotated source documentation in doc/
$ npm run build:docs

// minify browser version (http://coderaiser.github.io/minify/)
$ npm run minify:browser

see all npm tasks defined in package.json.