tentacoli   

Multiplexing requests and streams over a single connection since 2015.

• Install
• Example
• API
• TODO
• Acknowledgements
• License

Install

npm i tentacoli --save

Example

'use strict'

var tentacoli = require('./')
var net = require('net')
var from = require('from2')
var through = require('through2')
var pump = require('pump')

var server = net.createServer(function (original) {
  var stream = tentacoli()
  pump(stream, original, stream)

  stream.on('request', handle)
})

function handle (req, reply) {
  console.log('--> request is', req.cmd)
  reply(null, {
    data: 'some data',
    streams: {
      echo: req.streams.inStream.pipe(through.obj())
    }
  })
}

server.listen(4200, function () {
  var original = net.connect(4200)
  var instance = tentacoli()
  pump(original, instance, original)

  instance.request({
    cmd: 'a request',
    streams: {
      inStream: from.obj(['hello', 'world'])
    }
  }, function (err, result) {
    if (err) {
      throw err
    }

    console.log('--> result is', result.data)
    console.log('--> stream data:')

    result.streams.echo.pipe(through.obj(function (chunk, enc, cb) {
      cb(null, chunk + '\n')
    })).pipe(process.stdout)
    result.streams.echo.on('end', function () {
      console.log('--> ended')
      instance.destroy()
      server.close()
    })
  })
})

Yes, it is long.

API

• tentacoli()
• instance.request()
• instance.fire()
• instance.on('request', cb)

tentacoli([opts])

Creates a new instance of Tentacoli, which is a Duplex stream and inherits from multiplex

It accepts the following option:

• codec: an object with a encode and decode method, which will be used to encode messages. Valid encoding libraries are protocol-buffers and msgpack5. The default one is JSON. This capability is provided by net-object-stream.
• maxInflight: max number of concurrent requests in flight at any given moment.

instance.request(message, callback(err, res))

Sends a request to the remote peer.

• message is a standard JS object, but all streams contained in its streams property will be multiplexed and forwarded to the other peer.
• callback will be called if an error occurred or a response is available. The res.streams property will contain all streams passed by the other peer.

instance.fire(message, callback(err))

Sends a fire and forget request to the remote peer.

• message is a standard JS object, but all streams contained in its streams property will be multiplexed and forwarded to the other peer.
• callback will be called if there is an error while sending the message, or after the message has been sent successfully.

instance.on('request', callback(req, reply))

The 'request' event is emitted when there is an incoming request.

• req is the standard JS object coming from request, and all the streams contained in its streams property will have been multiplexed and forwarded from the other peer.
• reply is the function to send a reply to the other peer, and it follows the standard node callback pattern: reply(err, res). The res.streams property should contain all the streams that need to be forwarded to the other peer.

TODO

• [ ] battle test it, you can definitely help! I am particularly concerned about error handling, I do not want tentacoli to crash your process.
• [ ] figure out how to handle reconnects.
• [x] provide examples, with WebSockets (via websocket-stream net, SSL, etc..
• [ ] provide an example where a request is forwarded sender -> router -> receiver. With streams!
• [ ] tentacoli needs a microservice framework as its companion, but it is framework agnostic. We should build a seneca transport and probably something more lean too.

In the Browser

You will use websocket-stream to wire tentacoli to the websocket.

On the server:

'use strict'

var http = require('http')
var tentacoli = require('./')
var pump = require('pump')
var websocket = require('websocket-stream')
var server = http.createServer(serve)

websocket.createServer({
  server: server
}, handle)

function handle (sock) {
  var receiver = tentacoli()
  pump(sock, receiver, sock)
  receiver.on('request', function request (req, reply) {
    // just echo
    reply(null, req)
  })
}

server.listen(3000, function (err) {
  if (err) throw err
  console.error('listening on', server.address().port)
})

On the client:

'use strict'

var tentacoli = require('../')
var ws = require('websocket-stream')
var pump = require('pump')
var from = require('from2')

var URL = require('url')
var serverOpts = URL.parse(document.URL)
serverOpts.path = undefined
serverOpts.pathname = undefined
serverOpts.protocol = 'ws'
var server = URL.format(serverOpts)

var stream = ws(server)
var instance = tentacoli()

pump(stream, instance, stream)

instance.request({
  streams: {
    inStream: from.obj(['hello', 'world'])
  }
}, function (err, data) {
  if (err) throw err

  var res = data.streams.inStream
  res.on('data', function (chunk) {
    console.log(chunk)
  })
})

with Browserify

Browserify offers a way of packaging up this module for front-end usage. You will just need to install/specify the brfs transform.

As an example:

browserify -t brfs tentacoli.js > bundle.js

with WebPack

WebPack offers the more popular way of packaging up node modules for browser usage. You will just need to install/specify the brfs transform.

You should install webpack, transform-loader and brfs:

npm i webpack transform-loader brfs websocket-stream --save

Then, set this as your webpack configuration:

'use strict'

module.exports = {
  module: {
    postLoaders: [{
      loader: "transform?brfs"
    }]
  }
}

To build:

webpack --config webpack.config.js yourfile.js build.js

Acknowledgements

This library would not be possible without the great work of @mafintosh, @substack and @maxodgen. This library is fully based on their work, look at package.json!

Another great source of inspriation was jschan from which I borrowed a lot of ideas. Thanks Adrian Roussow for all the discussions around microservices, streams and channels.

Many thanks to @mcdonnelldean for providing an excuse to write this random idea out.

This project is kindly sponsored by nearForm.

License

MIT