stream-channels

Simple one-way stream multiplexer with very few features. For two-way (full duplex) multiplexing see the multiplex module.

npm install stream-channels

Usage

var channels = require('stream-channels')
var stream = channels()
 
stream.on('channel', function (channel) {
  console.log('new channel')
  channel.on('data', console.log)
  channel.on('end', function () {
    console.log('(no more data)')
  })
})
 
var ch1 = stream.createChannel()
var ch2 = stream.createChannel()
 
ch1.write('hello')
ch2.write('world')
 
ch1.end()
ch2.end()
 
stream.pipe(stream)

API

var stream = channels([options], [onchannel])

Create a new instance. Options include:

{
  limit: maxChannelsAllowedOpen // defaults to 1024
}

var writeableStream = stream.createChannel()

Create a new channel.

stream.on('channel', readableStream)

Emitted when a remote creates a new channel. Will emit the data the remote writes to it.

stream.setTimeout(ms, [ontimeout])

Emit a timeout when if the stream is inactive for ~ms milliseconds. Will start a heartbeat as well.

Wire Protocol

The wire protocol is as follows.

------------------------------
| length | channel-id | data |
------------------------------

• Length is a varint containing the binary length of channel-id and data.
• Channel id is a varint representing the current channel.
• Data is the buffer you wrote to a channel

Channels are lazily opened., The first time you receive data on a channel id, that channel is opened. Receiving an empty data buffer indicates that the channel is closed.

Messages received with length 0 should be ignored and can be used as a keep alive signal.

Back pressure

Back pressure will trigger on all channels when the slowest channel starts to back pressure.

License

MIT