idex.nucleus

Nucleus is flexible library to implement a distributed micro-service(-like) architecture in NodeJS.

Installation

$ npm install idex.nucleus

High level Nucleus architecture

Nucleus implements a two way communication layer based on Redis. Each service are called "Engine" which can communicate between each other via two different protocols:

Action

An action is similar to an HTTP request: you make a request, you get a response.

const { NucleusEngine } = require('Nucleus');

// Create an Engine that registers the Ping action.
class DummyEngine extends NucleusEngine {
  
  constructor () {
    super('Dummy', {
      automaticallyAutodiscover: true,
      automaticallyRetrievePendingActions: true
    });
  }
  
  // Register the `ping` method as the "Ping" action handler using the `@Nucleus ActionName` tag.
  /**
  * Pings
  * 
  * @Nucleus ActionName Ping
  * 
  * @returns {Promise<Object>}
  */
  ping () {
    // Every action is expected to return a Promise that resolves to an object.
    
    return Promise.resolve({ ping: "Ping" });
  }
  
}

// ---

// Instantiate the engines that was created.
const $dummyEngine = new DummyEngine();
const $testEngine = new NucleusEngine();

// Wait for both engine to be initialized and ready to use.
Promise.all([ $dummyEngine, $testEngine ])
  .then(async () => {
    // Use the Test engine to publish an action named "Ping".
    // Behind the scene, the Dummy engine will respond to the request by executing the $dummyEngine.ping function.
    const { ping } = await $testEngine.publishActionByNameAndHandleResponse('Ping', {});
    
    console.log(ping);
    // $ Ping
  });

Event

An event as a similar implementation than a NodeJS EventEmitter event, you can publish/subscribe to an event.

const { NucleusEngine, NucleusEvent } = require('Nucleus');

// Instantiate the engines that were created.
const $pingEngine = new NucleusEngine();
const $pongEngine = new NucleusEngine();
const $testEngine = new NucleusEngine();

// Create an event handler for the "Ping" channel.
$pingEngine.handleEventByChannelName('Ping', () => {
  console.log('PING');

  const $event = new NucleusEvent('Pong', {});

  // Publish an event to the "Pong" channel.
  process.nextTick($pingEngine.publishEventToChannelByName.bind($pingEngine, 'Pong', $event));
});

// Create an event handler for the "Pong" channel.
$pongEngine.handleEventByChannelName('Pong', () => {
  console.log('PONG');

  const $event = new NucleusEvent('Ping', {});

  // Publish an event to the "Ping" channel.
  process.nextTick($pongEngine.publishEventToChannelByName.bind($pongEngine, 'Ping', $event));
});

// Subscribe the Ping engine to the "Ping" channel.
$pingEngine.subscribeToChannelName('Ping');

// Subscribe the Pong engine to the "Pong" channel.
$pongEngine.subscribeToChannelName('Pong');

const $event = new NucleusEvent('Ping', {});

$testEngine.publishEventToChannelByName('Ping', $event);

// An infinite loop of "Ping" and "Pong" will be printed.

License

MIT License

Copyright (c) 2018 Sebastien Filion

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.