event-invoke

The invoker based on event model provides an elegant way to call your methods in another container via promisify functions. (like child-processes, iframe, web worker etc). (Inspired by node-ipc-call)

Usage

• Install the package

$ npm i -S event-invoke

Invoking method via child process

• Example code

// parent.js
const cp = require('child_process');
const { Invoker } = require('event-invoke');

const invokerChannel = cp.fork('./child.js');

const invoker = new Invoker(invokerChannel);

async function main() {
  const res1 = await invoker.invoke('sleep', 1000);
  console.log('sleep 1000ms:', res1);
  const res2 = await invoker.invoke('max', [1, 2, 3]); // 3
  console.log('max(1, 2, 3):', res2);
  invoker.destroy();
}

main();

// child.js
const { Callee } = require('event-invoke');

const calleeChannel = process;

const callee = new Callee(calleeChannel);

// async method
callee.register(async function sleep(ms) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
});

// sync method
callee.register(function max(...args) {
  return Math.max(...args);
});

callee.listen();

Invoking method via child process via custom channel

• Example code

// pm2.config.cjs
module.exports = {
  apps: [
    {
      script: 'invoker.js',
      name: 'invoker',
      exec_mode: 'fork',
    },
    {
      script: 'callee.js',
      name: 'callee',
      exec_mode: 'fork',
    }
  ],
};

// callee.js
import net from 'net';
import pm2 from 'pm2';
import {
  Callee,
  BaseCalleeChannel
} from 'event-invoke';

const messageType = 'event-invoke';
const messageTopic = 'some topic';

class CalleeChannel extends BaseCalleeChannel {
  constructor() {
    super();
    this._onProcessMessage = this.onProcessMessage.bind(this);
    process.on('message', this._onProcessMessage);
  }

  onProcessMessage(packet) {
    if (packet.type !== messageType) {
      return;
    }
    this.emit('message', packet.data);
  }

  send(data) {
    pm2.list((err, processes) => {
      if (err) { throw err; }
      const list = processes.filter(p => p.name === 'invoker');
      const pmId = list[0].pm2_env.pm_id;
      pm2.sendDataToProcessId({
        id: pmId,
        type: messageType,
        topic: messageTopic,
        data,
      }, function (err, res) {
        if (err) { throw err; }
      });
    });
  }

  destroy() {
    process.off('message', this._onProcessMessage);
  }
}

const channel = new CalleeChannel();
const callee = new Callee(channel);

// async method
callee.register(async function sleep(ms) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
});

// sync method
callee.register(function max(...args) {
  return Math.max(...args);
});

callee.listen();

// keep your process alive
net.createServer().listen();

// invoker.js
import pm2 from 'pm2';
import {
  Invoker,
  BaseInvokerChannel
} from 'event-invoke';

const messageType = 'event-invoke';
const messageTopic = 'some topic';

class InvokerChannel extends BaseInvokerChannel {
  constructor() {
    super();
    this._onProcessMessage = this.onProcessMessage.bind(this);
    process.on('message', this._onProcessMessage);
  }

  onProcessMessage(packet) {
    if (packet.type !== messageType) {
      return;
    }
    this.emit('message', packet.data);
  }

  send(data) {
    pm2.list((err, processes) => {
      if (err) { throw err; }
      const list = processes.filter(p => p.name === 'callee');
      const pmId = list[0].pm2_env.pm_id;
      pm2.sendDataToProcessId({
        id: pmId,
        type: messageType,
        topic: messageTopic,
        data,
      }, function (err, res) {
        if (err) { throw err; }
      });
    });
  }

  connect() {
    this.connected = true;
  }

  disconnect() {
    this.connected = false;
  }

  destroy() {
    process.off('message', this._onProcessMessage);
  }
}

const channel = new InvokerChannel();
channel.connect();

const invoker = new Invoker(channel);

setInterval(async () => {
  const res1 = await invoker.invoke('sleep', 1000);
  console.log('sleep 1000ms:', res1);
  const res2 = await invoker.invoke('max', [1, 2, 3]); // 3
  console.log('max(1, 2, 3):', res2);
}, 5 * 1000);

Web worker

TODO

Iframe

TODO

Browser page

TODO

License

MIT