nsq-service

Introduction

A Micro-Service architecture solution using MessageQueue (Currently, mainly using NSQ)

Quick start

####1. build business logic of each module in its manager.js file with fixed parameter formation: must contain 2 parameters, first is the data object, second is the callback function The manager.js file should look like this:

module.exports = {
    some_api : function( parameterObject, callback ){
       // some business logic
       // ...
    },
    
    some_other_api: function( parameterObject, callback ){
       // some other business logic
       // ...
    },

    // ...   
}

It's just suggested to use manager.js as the business logic file name, to compliant with the concept of manager which will be used in the later step

####2. Setup the NSQ configurations The configuration should look like this:

nsqServiceConfig: {
        address: '127.0.0.1',      // NSQ server address
        writerPort: 4150,          // NSQ writer port, default is 4150
        readerPort: 4150,          // NSQ reader port, default is 4150
        maxInFlight: 1,            // NSQ parameter `maxInFlight`
        maxAttempts: 5,            // NSQ parameter `maxAttempts`
        producerQueue: 'auth',     // Define the name of `producer` queue
        customerQueue: 'auth-cust',// Define the name of `customer` queue
        channel: 'main'            // Default NSQ Channel is `main`
}

####3. Start NSQ-Service In the very beginning of your project entry file, normally is app.js,

var app = require('express')    // or restify, koa, etc.
// ...
var NS = require('nsq-service')
NS.queue.setConfig( nsqServiceConfig )   // the config object defined above
NS.handler.addManager(require('./PATH/TO/MANAGER')) // add some manager
NS.handler.ready( function() {      
    // NSQ-service need to be ready before start the local service
    // ...
    app.listen(3000)
})

Concepts

####1. Producer and Customer Every module in a distributed architecture is a Producer and at the mean time, is a Customer too. The communication sequence is:

(1) module[A] want to invoke an api of module[B], module[A] will send a message to module[B]'s producerQueue, in that message, information of module[A]'s customerQueue is attached

(2) module[B] receive that message from module[A], parse the api and arguments out, invoke the specified api with those arguments, when finished, module[B] send the result back to module[A]'s customerQueue, according to the attached information

(3) module[A] receive the execution result, from its customerQueue, and then execute the coresponding callback

####2. MessageID and Async Every message contains a MessageID, which is composed by timestamp, machine name, and random numbers, it's very hard to get collision even in millions messages per second

Every message is executed asynchronously