mqtt-request

Latest Version: 1.0.0

mqtt-request is a HTTP like library, you can use it request anything like http.

Install

npm install mqtt mqtt-request

you need install mqtt

Usage

It is easy to use. There is only two instance methods request() and response()

response() is for server and request() is for client.

Example

const mqtt = require('mqtt')
const MqttRequest = require('mqtt-request').default

const client = new mqtt("mqtt://mqtt.example.com")
const r = new MqttRequest(client);

// for server
r.response("hello/world", (payload) => {
  return "hello " + payload.toString();
})

mqtt.on('connect', () => {
  // for client
  r.request("hello/world", 
  (payload) => {
    console.log("Get response:" + payload.toString());
  }, 
  "Robot" // <-- this is payload
  )
})

How to work

When client send request, the request() method will add extra message to raw topic

e.g.

Raw topic hello/world

Transform to hello/world/@request/{uuid} the {uudi} is generate with nanoid and @request is sign it is a request messsage.

After send the request message, the request will be push to request queue and add expires property to this request. When expires is larger than now the request will be remove from request queue and THIS request is unusable.

Server get the request and generate response topic hello/world/@response/{uuid}, then send the topic to client with payload or nothing.

Methods

MqttRequest(mqtt)

mqtt the mqtt instance

MqttRequest#request(topic, callback, payload)

topic [string] request topic, you can use anyhing word expect @request or @response

callback [Function] callback function, function callback(payload) the payload is raw mqtt payload

payload [any] anything you want to send server

MqttRequest#response(topic, callback)

topic [string] response topic

callback [Function] callback function, function callback(payload) the payload is sent to server, and if you want send payload to client, then you must return data at callback method, the data can be anything.

Example

r.response("hello/world", (payload) => {return payload.toString()})

if you return nothing, there will no payload send to client, but the client always received the response!