it-ws

Simple async iterables for websocket client connections

Table of contents

• Install
  • Browser <script> tag
• Usage
  • Example - client
  • Example - server
• API
  • import { connect } from 'it-ws/client'
  • import { createServer } from 'it-ws/server'
    • Example
• use with an http server
  • core, websocket wrapping functions
  • import duplex from 'it-ws/duplex'
  • import sink from 'it-ws/sink'
  • import source from 'it-ws/source'
• License
• Contribution

Install

$ npm i it-ws

Browser <script> tag

Loading this module through a script tag will make it's exports available as ItWs in the global namespace.

<script src="https://unpkg.com/it-ws/dist/index.min.js"></script>

Usage

Example - client

import { connect } from 'it-ws/client'
import { pipe } from 'it-pipe'

const stream = connect(WS_URL)

await stream.connected() // Wait for websocket to be connected (optional)

pipe(source, stream, sink)

Example - server

import { createServer } from 'it-ws/server'
import { pipe } from 'it-pipe'

const server = createServer(stream => {
  //pipe the stream somewhere.
  //eg, echo server
  pipe(stream, stream)
})

await server.listen(PORT)

API

import { connect } from 'it-ws/client'

connect(url, { binary: boolean })

Create a websocket client connection. Set binary: true to get a stream of arrayBuffers (on the browser). Defaults to true on node, but to strings on the browser. This may cause a problems if your application assumes binary.

For adding options to the WebSocket instance, as websockets/ws/blob/master/doc/ws.md#new-websocketaddress-protocols-options, you can provide an object with the websocket property into the connect options.

const stream = connect(url)
// stream is duplex and is both a `source` and `sink`.
// See this for more information:
// https://gist.github.com/alanshaw/591dc7dd54e4f99338a347ef568d6ee9#duplex-it

import { createServer } from 'it-ws/server'

Create async iterable websocket servers.

createServer(options?, onConnection)

options takes the same server options as ws module

onConnection(stream) is called every time a connection is received.

Example

One duplex service you may want to use this with is muxrpc

import { createServer } from 'it-ws/server'
import { connect } from 'it-ws/client'
import { pipe } from 'it-pipe'

createServer({
  onConnection: (stream) => {
    // pipe duplex style to your service
    pipe(stream, service.createStream(), stream)
  }
})
.listen(9999)

const stream = client.createStream()

await pipe(
  stream,
  connect('ws://localhost:9999'),
  stream
)

if the connection fails, the stream will throw

try {
  await pipe(
    stream,
    connect('ws://localhost:9999'),
    stream
  )
} catch (err) {
  // handle err
}

To run the server over TLS:

createServer({
  key: fs.readFileSync('test/fixtures/keys/agent2-key.pem'),
  cert: fs.readFileSync('test/fixtures/keys/agent2-cert.pem')
  // other options
})
.listen(9999)

To add client-authentication to the server, you can set verifyClient. Documentation here.

function verifyClient (info) {
  return info.secure == true
}
createServer({
  verifyClient: verifyClient
  // other options
})

use with an http server

if you have an http server that you also need to serve stuff over, and want to use a single port, use the server option.

import http from 'http'

const server = http.createServer(function(req, res){...}).listen(....)

createServer({
  server: server
  // other options
})

core, websocket wrapping functions

these modules are used internally, to wrap a websocket. you probably won't need to touch these, but they are documented anyway.

import duplex from 'it-ws/duplex'

turn a websocket into a duplex stream. If provided, opts is passed to sink(socket, opts).

WebSockets do not support half open mode. see allowHalfOpen option in net module

If you have a protocol that assumes halfOpen connections, but are using a networking protocol like websockets that does not support it, I suggest using it-goodbye with your protocol.

The duplex stream will also contain a copy of the properties from the http request that became the websocket. they are method, url, headers and upgrade.

also exposed at: import { duplex } from 'it-ws'

import sink from 'it-ws/sink'

Create a Sink that will write data to the socket. opts may be {closeOnEnd: true, onClose: onClose}. onClose will be called when the sink ends. If closeOnEnd=false the stream will not close, it will just stop emitting data. (by default closeOnEnd is true)

If opts is a function, then onClose = opts; opts.closeOnEnd = true.

import sink from 'it-ws/sink'
import { pipe } from 'it-pipe'
import each from 'it-foreach'
import delay from 'delay'

// connect to the echo endpoint for test/server.js
var socket = new WebSocket('wss://echo.websocket.org')

// write values to the socket
pipe(
  async function * () {
    while (true) {
      yield 'hello @ ' + Date.now()
    }
  }(),
  // throttle so it doesn't go nuts
  (source) => each(source, () => delay(100))
  sink(socket)
);

socket.addEventListener('message', function(evt) {
  console.log('received: ' + evt.data);
});

also exposed at import { sink } from 'it-ws'

import source from 'it-ws/source'

Create a Source that will read data from the socket.

import { pipe } from 'it-pipe'
import source from 'it-ws/source'
import { toString } from 'uint8arrays/to-string'

pipe(
  // connect to the test/server.js endpoint
  source(new WebSocket('ws://localhost:3000/read')),
  async (source) => {
    for await (const buf of source) {
      console.info(toString(buf))
    }
  }
);

also exposed at import { source } from 'it-ws'

License

Licensed under either of

• Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
• MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.