oak-tools

oak-tools

Helpful utilities for developing oak applications

Install

npm install --save oak-tools

Documentation

Head on over to the documentation page!

Usage

oak-tools consists of a few helpful utility methods. Everything exposed from the module is a Class and needs to be constructed using new, except the logger

logger()

The logger is based off pino and has nearly the same same option parameters. The following example are the default options.

const { logger } = require('oak-tools')
let log = logger({
  // these are the default properties
  level: 'info',
  stream: process.stdout,
  pretty: false
})
log.info('sup')
log.error({
  err: new Error('crap...')
})
log.debug({
  msg: 'debug message here',
  now: Date.now()
})

server(type)

The server is extended from a good 'ol EventEmitter2. Head here for full documentation on the server class

const msgpack = require('msgpack5')()
const Server = require('oak-tools').server('websocket')

// all these options are, well... optional
let server = new Server({
  // these are the default properties
  port: 9500,
  host: 'localhost',
  serializer: { encode, decode } = msgpack
})

server
  .on('error', function (err) {
    console.error('* client error', err)
  })
  .on('connection', function (ID) {
    console.log('* client connection: ', ID)
  })
  .on('reconnect', function (ID) {
    console.log('* client reconnect: ', ID)
  })
  .on('close', function (ID) {
    console.log('* client closed', ID)
  })
  .on('who.is.the.man.now', function () {
    server.pub('heres.who', {
      answer: 'you are. http://www.yourethemannowdog.com/'
    })
  })

client(type)

The client API is similar to server, but it has both a sub and a pub method.

const { join } = require('path')

let Client = require(join(__dirname, '..')).client('websocket')

let client = new Client({
  id: 'sean connery' // defaults to random UUID
})

client.on('ready', function () {
  console.log('* client is connected')
  client
    .on('heres.who', function ({ answer }) {
      console.log(answer)
    })
    .pub('who.is.the.man.now')
})

Message Rationale & Flow

The goal of the server/client is to wrap up all the higher level messaging operations to be more protocol agnostic (as well as non-repetitive). This means we have a couple more steps than a normal TCP or WebSocket flow:

Client -> Server

• Client publishes on a namespace

  client > pub('foo.bar', { my: 'message' })

• The namespace and message get split into an flat array, where the last item is the message

  client > outbound message [ 'foo', 'bar', { my: 'message' } ]

• Payload gets encoded by the client

  client > encode(array) // <Buffer a5 68 65 6c 6c 6f>

• Client sends encoded message to the server

  client > send(payload)

• Server receives payload Buffer

  server > on('message', decode)

• Server receives and unpacks the payload

  server > decode(payload) // our array

• Server reconstructs the array, and emits the message

  server > emit('foo.bar', { my: 'message' })

Server -> Client(s)

• Client sends a subscription message to the server, through its binding

  client > on('foo.*', handler)

• Server receives a subscription event from the client

  server > on('_sub') // remember client wants 'foo.*' messages

  Time passes...

• Server sends an event to all clients that subscribed

  server > pub('foo.baz', { my: 'message' }) // matches anyone who sent _sub to foo.*

• Encode and write the same way the client does to each socket

  server > each connections send(payload)

• Client receives payload, unpacks, and emits it

  client > on('foo.*', fn(data)) // this.event === foo.baz

Serializer

On both server and client, encoder and decoder to pass messages. The serializer consists of the encoding and decoding methods to use against payloads. By default, we use msgpack5, but doing something as simple as this will work:

new clientOrServer({
  serializer: {
    encode: JSON.stringify,
    decode: JSON.parse
  }
})

Dependencies

Package	Version	Dev
eventemitter2	~4.1.0	✖
mdns-js	~0.5.3	✖
minimatch	~3.0.3	✖
msgpack5	~3.4.1	✖
pino	~4.4.0	✖
safe-buffer	~5.1.0	✖
swagger-client	~3.0.2	✖
uuid	~3.0.1	✖
ws	~3.0.0	✖
ws-heartbeats	~1.0.0	✖
coveralls	~2.13.0	✔
docdash	~0.4.0	✔
istanbul	~0.4.5	✔
jsdoc	~3.5.0	✔
node-readme	~0.1.9	✔
standard	~10.0.0	✔
tap-difflet	~0.7.0	✔
tape	~4.7.0	✔

Contributing

Contributions welcome; Please submit all pull requests against the master branch. If your pull request contains patches or features, you should include relevant unit tests. Thanks!

Authors

• Flynn Joffray - [e-mail]
• Nir Ziv - [e-mail]

License

• Apache-2.0 : http://opensource.org/licenses/Apache-2.0