@universis/racket

An inter-process event service which implements the communication between processes by sending and receiving messages in an active inter-connector environment.

This implementation is very important for applications and services which are running in cluster mode and every cluster worker should inform cluster for something.

Install

npm i @universis/racket

Usage

InterProcessEventEmitter

InterProcessEventEmitter handles process events and emits them even if process is running in cluster mode or under pm2. Each worker of a cluster or the process itself has the option to handle inter-process events by using InterProcessEventEmitter.subscribe().

Register globally InterProcessEventEmitter handler:

import { InterProcessEventEmitter } from './InterProcessEventEmitter';
InterProcessEventEmitter.register();

or use @universis/racket/register as --require script under nodejs

node --require @universis/racket/register myapp.js

Start sending process events

import { InterProcessEventEmitter } from '@universis/racket';

new InterProcessEventEmitter().emit({
    body: 'Hello World!'
});

or subscribing for new events

import { InterProcessEventEmitter } from '@universis/racket';

const emitter = new InterProcessEventEmitter().subscribe((message) => {
    // write your code here
});

...
emitter.unsubscribe();

ProcessEventEmitter

ProcessEventEmitter uses @universis/racket service to send and receive process events. @universis/racket event service is an HTTP service which acts as a proxy of all events emitted by any client of that service. Process events are being collected by the service and transmitted to any client that has been subscribed for receiving messages.

Start @universis/racket/platform-server as a standalone service

npx @universis/racket/platform-server/register

or register @universis/racket/platform-server under pm2

pm2 start @universis/racket/platform-server/register -n racket

This operation will start an instance of @universis/racket service which is a typical HTTP service and starts listening for process subscription under http://localhost:14440

ProcessEventEmitter.subscribe

Any process may use ProcessEventEmitter class and subscribe for new events:

import { ProcessEventEmitter } from '@universis/racket';

const subscription = new ProcessEventEmitter().subscribe((event) => {
    // write your code here
});

// unsubscribe
subscription.unsubscribe();

When service has been configured to run in different port use serviceHost param to define service host:

import { ProcessEventEmitter } from '@universis/racket';

const subscription = new ProcessEventEmitter('http://localhost:12345/').subscribe((event) => {
    // write your code here
});

ProcessEventEmitter.emit

Use ProcessEventEmitter.emit(event) for sending messages to all subscribers:

new ProcessEventEmitter().emit({
    type: 'message',
    value: {
        body: 'Hello World!'
    }
});