EventTransmitter for Streams

Attach events to any stream pipeline and emit those events at receiving stream endpoints.

EventTransmitter transmits events and their parameters along standard stream pipelines. It requires at least two instances: one to transmit encoded event information, and another to listen for and emit events, sanitizing the stream of event metadata in the process for further piping.

Install

npm install event-transmitter

Include

var EventTransmitter = require('event-transmitter')

Transmit Events

Use EventTransmitter to transmit events (works like ee.emit). But first you must pipe your EventTransmitter instance to a stream that is connected to where you ultimately want to receive and handle events.

// create a new EventTransmitter instance
var et = new EventTransmitter()

// pipe the EventTransmitter to some stream pipeline
et.pipe(stream_pipeline)

// call et.transmit() to send an event down the pipeline
et.transmit('header', { stuff: 'here is some stuff' }, 'A String')

Receive and Emit Events Locally

Listen downstream for EventTransmitter events. Just pipe the stream containing the EventTransmitter events to a new EventTransmitter.Listener() which will listen for and emit them locally.

// create a new EventTransmitter Listener instance
var etListener = new EventTransmitter.Listener()

// pipe the stream pipeline with transmitter events to the listener
stream_pipeline.pipe(etListener)

// set up your event handler to handle events from the pipeline
etListener.on('header', function(stuff, aString){
  console.log('emitting a "header" event with object:', stuff, 'and string:', aString)
})

Important

Note: EventTransmitter adds event metadata to the streams it is piped through and should be placed in the pipeline between where data will otherwise be used. Your EventTransmitter instance will sanitize stream content as it passes through its listener, removing event metadata from the stream, restoring the stream contents.

License

The MIT License (MIT)
Copyright (c) 2017 Arjun Mehta