Snub

Pub Sub message system, supports middleware, single delivery, replys and clusterable.

Usage

npm install snub

Basic Example

With redis installed and running with default port and no auth.

const Snub = require('snub');
const snub = new Snub();

// create listener for 'hello'
snub.on('hello', (payload) => {
  console.log('Recieved => ', payload);
});

// send 'hello' to single listener.
snub.mono('hello', 'world').send();

For further examples take a look in examples.

Advanced Setup

Optional config, defaults are applied if omitted.

const Snub = require('snub');
const snub = new Snub({
    prefix: 'snub', // prefix all snub pub/sub messages
    port: 6379, // redis port
    host: '127.0.0.1', // redis host
    auth: null,   // redis auth
    debug: false, // dump debug junk
    timeout: 5000 // reply timeout, we cant listen forever,
    monoWait: 50,  // used to help mono delivery messages to get dispersed evenlyish, this is a max wait time. will randomize between 0-monoWait, if you have small amount of instances set this low. poly does not use this value.
    redisStore: { // option, if you would like the store be on a seperate instanc from pub/sub activity
      port: 6379, // redis port
      host: '127.0.0.1', // redis host
      auth: null,   // redis auth
    },
    intercepter: async (payload, reply, channel, pattern) => {
      // payload be mutated directly, reply fn can be called early. (if you reply and return true you might have an uninteded outcome)
      return true; // returning false will not exectute the listener.
    }
  });

API

snub.on('eventname', (payload, [reply]) => {});

• Method is run when an event is triggered.
• Use patterns in subscribers like so 'h[ae]llo' or hell*
• Reply is optionaly a function to reply at with a single param. reply({})
• you can also namespace events hello.one to allow easy removal with snub.off('hello.one')

snub.once('eventname', (payload, [reply]) => {});

Same as .on but event will only trigger once.

snub.off('eventname');

• Remove all event listeners by name
• append namespace to remove single listener if you have mutliple.

snub.poly('eventname', payload).send([function]);

Emits an event trigger with the payload .send() accepts and optional callback function which carries a number value which will indicate the amount of listeners that heard the event trigger. Poly will deliver the message and payload to all listeners.

snub.poly('eventname').replyAt(function(), [optional timeout]).send([function]);

Allows the event to be replied to, since this will get delivered to all listeners the reply will prossibly be responded to multiple times.

snub.mono('eventname', payload).send([function]);

Emits an event trigger with the payload .send() accepts and optional callback function which carries a number value which will indicate the amount of listeners that heard the event trigger (will always be 0 or 1 for mono). Mono will only be delivered to a single listener, this is first come first served, there is not methodology or way to control this as of yet, think of it as random delivery.

snub.mono('eventname', payload).sendDelay(5);

number of seconds to delay the event being sent. this is stores in redis so will persist restarts.

snub.poly('eventname', payload).replyAt(function(), [optional timeout]).send([function]);

Allows the event to be replied to, reply can only run once.

snub.use(middlewareMethod);

Snub accepts middleware, it will hand the snub instance to the middleware method.

Some handy middleware

• Snub-HTTP