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A test suite and interface you can use to implement a stream muxer. "A one stop shop for all your muxing needs"

The primary goal of this module is to enable developers to pick and swap their stream muxing module as they see fit for their application, without having to go through shims or compatibility issues. This module and test suite was heavily inspired by abstract-blob-store.

Publishing a test suite as a module lets multiple modules all ensure compatibility since they use the same test suite.

The API is presented with both Node.js and Go primitives, however, there is no actual limitations for it to be extended for any other language, pushing forward the cross compatibility and interop through different stacks.

Lead Maintainer

Jacob Heun

Modules that implement the interface

Send a PR to add a new one if you happen to find or write one.


Include this badge in your readme if you make a new module that uses interface-stream-muxer API.



Install interface-stream-muxer as one of the dependencies of your project and as a test file. Then, using mocha (for JavaScript) or a test runner with compatible API, do:

const test = require('interface-stream-muxer')
const common = {
  async setup () {
    return yourMuxer
  async teardown () {
    // cleanup
// use all of the test suits





A valid (one that follows this abstraction) stream muxer, must implement the following API:

const muxer = new Muxer([options])

Create a new duplex stream that can be piped together with a connection in order to allow multiplexed communications.


const Muxer = require('your-muxer-module')
const pipe = require('it-pipe')
// Create a duplex muxer
const muxer = new Muxer()
// Use the muxer in a pipeline
pipe(conn, muxer, conn) // conn is duplex connection to another peer

options is an optional Object that may have the following properties:

  • onStream - A function called when receiving a new stream from the remote. e.g.
    // Receive a new stream on the muxed connection
    const onStream = stream => {
      // Read from this stream and write back to it (echo server)
        source => (async function * () {
          for await (const data of source) yield data
    const muxer = new Muxer({ onStream })
    // ...
    Note: The onStream function can be passed in place of the options object. i.e.
    new Mplex(stream => { /* ... */ })
  • onStreamEnd - A function called when a stream ends.
       // Get notified when a stream has ended
      const onStreamEnd = stream => {
        // Manage any tracking changes, etc
      const muxer = new Muxer({ onStreamEnd, ... })
  • signal - An AbortSignal which can be used to abort the muxer, including all of it's multiplexed connections. e.g.
    const controller = new AbortController()
    const muxer = new Muxer({ signal: controller.signal })
    pipe(conn, muxer, conn)
  • maxMsgSize - The maximum size in bytes the data field of multiplexed messages may contain (default 1MB)


Use this property as an alternative to passing onStream as an option to the Muxer constructor.

const muxer = new Muxer()
// ...later
muxer.onStream = stream => { /* ... */ }


Use this property as an alternative to passing onStreamEnd as an option to the Muxer constructor.

const muxer = new Muxer()
// ...later
muxer.onStreamEnd = stream => { /* ... */ }

const stream = muxer.newStream([options])

Initiate a new stream with the remote. Returns a duplex stream.


// Create a new stream on the muxed connection
const stream = muxer.newStream()
// Use this new stream like any other duplex stream:
pipe([1, 2, 3], stream, consume)

const streams = muxer.streams

The streams property returns an array of streams the muxer currently has open. Closed streams will not be returned. => {
  // Log out the stream's id


Attach muxer to a Connection

muxedConn, err := muxer.Attach(conn, isListener)

This method attaches our stream muxer to an instance of Connection defined by interface-connection.

If err is passed, no operation should be made in conn.

isListener is a bool that tells the side of the socket we are, isListener = true for listener/server and isListener = false for dialer/client side.

muxedConn interfaces our established Connection with the other endpoint, it must offer an interface to open a stream inside this connection and to receive incomming stream requests.

Dial(open/create) a new stream

stream, err := muxedConn.newStream()

This method negotiates and opens a new stream with the other endpoint.

If err is passed, no operation should be made in stream.

stream interface our established Stream with the other endpoint, it must implement the ReadWriteCloser.

Listen(wait/accept) a new incoming stream

stream := muxedConn.Accept()

Each time a dialing peer initiates the new stream handshake, a new stream is created on the listening side.


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