Microwork.js - 利用RabbitMQ在node.js中創建分布式可擴展的微服務

Microwork.js

Microwork.js是一個庫，實現利用RabbitMQ在node.js中創建分布式可擴展的微服務。

Installation

npm install --save microwork

Requirements

Since Microwork.js is written in ES6, it uses babel to compile the code before publishing. Currently we're usinges2015-node babel preset that only works in latest stable node (4.x or later).

Features

• Simple interface for building distributed (micro)services
• Easy way to scale services both horizontally (by adding more nodes) and vertically (by adding more subscribers)
• Extensible with plugins

Usage

Quick start

Example service that subscribe to messages from do.work topic and does some work with incoming data (in this case it just appends world! to incoming string):

import Microwork from 'microwork';

// create task runner
const runner = new Microwork({host: 'your.rabbit.host', exchange: 'your.exchange'});
// add worker to specific topic
await runner.subscribe('do.work', (msg, reply) => {
    reply('response.topic', msg + ' world!');
});
// after work is done - cleanup
await runner.stop();</pre> 
 
 Example service that subscribes to messages from response.topic and logs them to console, as well as sends processing request to previously defined service: 

import Microwork from 'microwork';

// create master
const master = new Microwork({host: 'your.rabbit.host', exchange: 'your.exchange'});
// listen for reply from workers
await master.subscribe('response.topic', (msg) => {
    console.log(msg); // -> "hello world!"
});
// send message to workers
await master.send('do.work', 'hello');
// after work is done - cleanup
await master.stop();</pre> 
 
  
     Using multiple subscribers to distribute tasks 

 Example service that adds two different subscribers to the same topic, they will be rotated by RabbitMQ using round-robin strategy (see RabbitMQ tutorial 2 ): 
// ...
// add worker to specific topic
await runner.subscribe('do.work', (msg, reply) => {
    reply('response.topic', msg + ' world!');
});
// add another worker
// round-robin will be used to cycle between workers
await runner.subscribe('do.work', (msg, reply) => {
    reply('response.topic', msg + ' world! Replies to every other message.');
});
 
 
You can do achieve the same result by instantiating two different services (e.g. on different servers) and subscribing to the same exchange and topic from them.

  
     Plugins 
Microwork provides basic support for plugins. Following plugins are currently available:
  
     Hardware stats plugin 
Provides basic hardware stats about node (currently includes cpu with average load and memory information).
Example usage:
import HardwareStat from 'microwork/lib/plugins/hardwarestat';

// create service
const service = new Microwork({host: 'docker.dev', exchange});
// register plugin
service.registerPlugin(HardwareStat);
// hardware autoreport interval, defaults to 60s
service.hardwareReportInterval = 60000;
// start autoreport
service.autoreportHardwareStats();</pre> 
 
 To listen to the stats you need to tap into microwork.node.status topic, like so: 

await service.subscribe('microwork.node.status', (stats) => {
    console.log(stats); // <- stats object
    /* e.g.:
    {
        "cpu": {
            "cpus": 8, // count
            "load": [1.1962890625,1.35107421875,1.34912109375] // avg load in last 1m, 5m, 15m
        },
        "mem": { // in bytes
            "used": 15742152704,
            "free": 1437716480,
            "total": 17179869184
        }
    }
     */
});
 
 
  
     Health plugin 

Provides basic keep-alive signal from node.
Example usage:
import HealthCheck from 'microwork/lib/plugins/healthcheck';

// create service
const service = new Microwork({host: 'docker.dev', exchange});
// register plugin
service.registerPlugin(HealthCheck);
// report interval in ms, defaults to 30s
service.healthchecksReportInterval = 30000;
// start autoreport
service.autoreportHealth();</pre> 
 
 To listen to the keep-alive signals you need to tap into microwork.node.alive topic, like so: 

await service.subscribe('microwork.node.alive', (id) => {
    console.log(id); // <- live node id
});
 
 
  
     Subscribers info plugin 

Provides basic info about subscribers from node.
Example usage:
import SubscriberStats from 'microwork/lib/plugins/substats';

// create service
const service = new Microwork({host: 'docker.dev', exchange});
// register plugin
service.registerPlugin(SubscriberStats);
// init subs reporting
service.initSubscribersReporting();</pre> 
 
 To retrieve the subscribers you need to tap into microwork.node.subscribers topic and then send an empty message to microwork.node.report.subscribers topic, like so: 

await service.subscribe('microwork.node.subscribers', (info) => {
    console.log(info); // <- node info including ID and array of subscribed topics
    / e.g.
    { id: '3a4a5bd0-9c58-4677-b89b-9e5107da265f',
      subscribers:
       [ { topic: 'test.sub', subscribers: 1 },
         { topic: 'test.other.sub', subscribers: 2 },
         { topic: 'microwork.node.subscribers', subscribers: 1 },
         { topic: 'microwork.node.report.subscribers', subscribers: 1 } ] }
     /
});

await service.send('microwork.node.report.subscribers');</pre> 
 
  
     License 

 MIT 
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