基於mqtt的消息推送（二）服務端實現

基於Mosca的服務端實現

Mosca簡介，Mosca基於node.js開發，特性引用自項目首頁介紹如下：

Features

• MQTT 3.1 and 3.1.1 compliant.
• QoS 0 and QoS 1.
• Various storage options for QoS 1 offline packets, and subscriptions.
• As fast as it is possible.
• Usable inside ANY other Node.js app.
• Supports Node.js v0.10 and v0.12.
• Supports io.js v1.x and v2.x and v3.x (please do not use v3.1.0)

需要特別說明的是Mosca並不支持Qos 2。

為什么選擇Mosca？首先基於node.js開發，上手難度相對較小，其次協議支持完整，除了不支持Qos 2，其它的基本都支持。持久化支持redis以及mongo。二次開發接口簡單。部署非常簡單，並且支持docker鏡像。

開發步驟

安裝Mosca

本文環境假設你已經安裝了node.js環境以及redis，我本機的環境如下：mac ox 10.11.2 node.js v0.12 redis最新版本。

Mosca項目托管地址：https://github.com/mcollina/mosca
官方wiki：https://github.com/mcollina/mosca/wiki

安裝非常簡單，源引自官方說明如下：

Standalone

1 2	npm install mosca bunyan -g mosca -v | bunyan

Embedded

1	npm install mosca --save

啟動腳本

官方給了一個簡單的例子，如下是我現在使用的測試代碼：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81

var mosca = require('mosca') //ascoltatore是Mosca作者開發的一個訂閱與發布類庫，Mosca核心的訂閱與發布模型 var ascoltatore = { type: 'redis', //指定類型，mongo的寫法請參考官方wiki redis: require('redis'), db: 1, port: 6379, return_buffers: true, // to handle binary payloads //指定數據保留多長時間，單位毫秒 ttl: { // TTL for subscriptions is 23 hour subscriptions: 23 * 60 * 60 * 1000, // TTL for packets is 23 hour packets: 23 * 60 * 60 * 1000, }, host: "localhost" }; //基本參數設置 var moscaSettings = { port: 1883, //設置監聽端口 backend: ascoltatore, maxInflightMessages: 10240, //設置單條消息的最大長度，超出后服務端會返回 //設置WebSocket參數 http: { port: 1884, bundle: true, static: './' }, //數據持久化參數設置 persistence: { factory: mosca.persistence.Redis, db: 1, port: 6379, return_buffers: true, // to handle binary payloads ttl: { // TTL for subscriptions is 23 hour subscriptions: 23 * 60 * 60 * 1000, // TTL for packets is 23 hour packets: 23 * 60 * 60 * 1000, }, host: "localhost" } }; //如果需要用戶登錄驗證權限，需要改寫此方法 //這里以簡單判斷了用戶名和密碼為例，真實環境可以連接實際業務系統的鑒權服務 var authenticate = function(client, username, password, callback) { var authorized = (username === 'test' && password.toString() === 'passwd'); if (authorized) client.user = username; callback(null, authorized); } function authPub(client, topic, payload, callback) { callback(null, payload); } function authSub(client, topic, callback) { callback(null, topic); } var server = new mosca.Server(moscaSettings); server.on('ready', setup); server.on('clientConnected', function(client) { console.log('client connected', client.id); }); server.on('published', function(packet, client) { console.log('Published', packet.topic + packet.payload); }); // fired when the mqtt server is ready function setup() { server.authenticate = authenticate; server.authorizePublish = authPub; server.authorizeSubscribe = authSub; console.log('Mosca server is up and running') }

二次開發

可以監聽的事件列表

• clientConnected : when a client is connected; the client is passed as a
  parameter.
• clientDisconnecting : when a client is being disconnected; the client is
  passed as a parameter.
• clientDisconnected : when a client is disconnected; the client is passed as
  a parameter.
• published : when a new message is published; the packet and the client are
  passed as parameters.
• delivered : when a client has sent back a puback for a published message; the packet and the client are
  passed as parameters.
• subscribed : when a client is subscribed to a topic; the topic and the
  client are passed as parameters.
• unsubscribed : when a client is unsubscribed to a topic; the topic and the
  client are passed as parameters.

有了上面可以監聽到事件你就可以根據自己的業務進行相應的開發，攔截特定的事件並添加業務代碼

ascoltatore托管地址 https://github.com/mcollina/ascoltatori

高級參數設置可以參考 https://github.com/mcollina/mosca/wiki/Mosca-advanced-usage

權限驗證可以參考 https://github.com/mcollina/mosca/wiki/Authentication-&-Authorization

配置ssl可以參考 https://github.com/mcollina/mosca/wiki/TLS-SSL-Configuration

配置WebSocket可以參考 https://github.com/mcollina/mosca/wiki/MQTT-over-Websockets

寫在最后

感謝Mosca的作者mcollina，Mosca非常強大，並且足夠簡單。下篇文章會介紹如何利用IOS和Android開源客戶端類庫與Mosca對接，敬請期待！

 

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轉載： http://targe.me/2015/12/29/mqtt-second/