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<h1 align="center"> <img alt="human vasculatory system" src="https://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Circulatory_System_no_tags.svg/259px-Circulatory_System_no_tags.svg.png" height="300" /> <br /> vas </h1> <h4 align="center"> :seedling: composable client/server data services using <a href="https://pull-stream.github.io">pull streams</a> </h4> <div align="center"> <!-- stability --> <a href="https://nodejs.org/api/documentation.html#documentation_stability_index"> <img src="https://img.shields.io/badge/stability-experimental-orange.svg?style=flat-square" alt="stability" /> </a> <!-- npm version --> <a href="https://npmjs.org/package/vas"> <img src="https://img.shields.io/npm/v/vas.svg?style=flat-square" alt="npm version" /> </a> <!-- build status --> <a href="https://travis-ci.org/ahdinosaur/vas"> <img src="https://img.shields.io/travis/ahdinosaur/vas/master.svg?style=flat-square" alt="build status" /> </a> <!-- test coverage --> <a href="https://codecov.io/github/ahdinosaur/vas"> <img src="https://img.shields.io/codecov/c/github/ahdinosaur/vas/master.svg?style=flat-square" alt="test coverage" /> </a> <!-- downloads --> <a href="https://npmjs.org/package/vas"> <img src="https://img.shields.io/npm/dm/vas.svg?style=flat-square" alt="downloads" /> </a> <!-- standard style --> <a href="https://github.com/feross/standard"> <img src="https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat-square" alt="standard style" /> </a> </div> <details> <summary>table of contents</summary> <li><a href="#features">features</a></li> <li><a href="#demos">demos</a></li> <li><a href="#example">example</a></li> <li><a href="#concepts">concepts</a></li> <li><a href="#usage">usage</a></li> <li><a href="#install">install</a></li> <li><a href="#inspiration">inspiration</a></li> </details>

features

for a user interface complement, see inu

demos

if you want to share anything using vas, add your thing here!

example

var vas = require('vas')
var pull = vas.pull
var values = require('object-values')

var service = {
  name: 'things',
  manifest: {
    all: 'source',
    get: 'async'
  },
  methods: function (server, config) {
    return { all, get }

    function all () {
      const things = values(config.data)
      return pull.values(things)
    }

    function get (id, cb) {
      cb(null, config.data[id])
    }
  },
  permissions: function (server, config) {
    return { get }

    function get (id) {
      if (id === 'nobody') {
        return new Error('nobody is not allowed.')
      }
    }
  },
  handlers: function (server, config) {
    return [
      function (req, res, next) {
        console.log('cookie:', req.headers.cookie)
        next()
      }
    ]
  }
}

// could also attach db connection, file descriptors, etc.
var config = {
  data: {
    1: 'human',
    2: 'computer',
    3: 'JavaScript'
  }
}

var port = 6000
var url = `ws://localhost:${port}`
var server = vas.listen(service, config, { port })
var client = vas.connect(service, config, { url })

client.things.get(1, (err, value) => {
  if(err) throw err
  console.log('get', value)
  // get human
})

pull(
  client.things.all(),
  pull.drain(v => console.log('all', v))
)
// all human
// all computer
// all JavaScript

setTimeout(function () {
  server.close()
  client.close()
}, 1000)

for a more complete example, see ./example, which you can run with npm run example and query using command-line using npm run example:cli -- things.find.

concepts

let's say we're writing a todo app (so lame right).

we want to be able to get all the todo items, update a todo item, and add another one.

if we think of these methods as functions, it might look like this (using knex):

const toPull = require('stream-to-pull-stream')
const Db = require('knex')

const db = Db({
  client: 'sqlite3',
  connection: {
    filename: './mydb.sqlite'
  }
})

const methods = {
  getAll,
  update,
  add
}

function getAll () {
  return toPull(db('todos').select().stream())
}

function update (nextTodo, cb) {
  db('todos')
    .where('id', nextTodo.id)
    .update(nextTodo)
    .asCallback(cb)
}

function add (todo, cb) {
  db('todos').insert(todo).asCallback(cb)
}

what if we could call these functions directly from the front-end?

to do so, we need to specify which functions are available and of what type they are, which is called a manifest.

const manifest = {
  getAll: 'source',
  update: 'async',
  add: 'async'
}

where 'source' corresponds to a source pull stream and 'async' corresponds to a function that receives an error-first callback.

this manifest provides us with enough information to construct a mirrored function on the client:

pull(
  getAll(),
  pull.log()
)

together, this could become a service, complete with a name and version:

const service = {
  name: 'todos',
  version: '1.0.0',
  manfest,
  methods
}

what if we had multiple services that need to share some configuration, such as a single database connection?

to do so, we want to pass a config object to the service methods, in particular a function that receives the config and returns the method functions.

combine these concepts together and welcome to vas. :)

usage

a vas service is a definition for a duplex stream that responds to requests.

a vas service is defined by an object with the following keys:

many vas services can refer to a single service or an Array of services

vas = require('vas')

the top-level vas module is a grab bag of all vas/* modules.

you can also require each module separately like require('vas/listen').

vas.listen(services, config, options)

creates a server with createServer(services, config), then

listens to a port and begins to handle requests from clients using pull-ws-server

options is an object with the following (optional) keys:

vas.connect(client, config, options)

creates a client with createClient(services, config), then

connects the client to a server over websockets using pull-ws-server

options is an object with the following (optional) keys:

vas.command(services, config, options, argv)

run a command on a server as a command-line interface using muxrpcli

options are either those passed to vas.listen or vas.connect, depending on if argv[0] === 'server'

argv is expected to be process.argv.


server = vas.createServer(services, config, options)

a vas server is an instantiation of a service that responds to requests.

createServer returns an object that corresponds to the (recursive) services and respective methods returned by methods.

options is an object with the following (optional) keys:

client = vas.createClient(services, config, options)

a vas client is a composition of manifests to makes requests.

createClient returns an object that corresponds to the (recursive) services and respective methods in manifest.

options is an object with the following (optional) keys:

server.createStream(id)

client.createStream(id)

returns a duplex pull stream using muxrpc

for a server, if id is passed in, will bind each method or permission function with id as this.id.

frequently asked questions (FAQ)

how to reduce browser bundles

by design, service definitions are re-used between client and server creations.

this leads to all the server code being included in the browser, when really we only need the service names and manifests to create the client.

to reduce our bundles to only this information (eliminating any require calls or other bloat in our service files), use the evalify browserify transform.

to evalify only service files, where service files are always named service.js, install evalify and add the following to your package.json

{
  "browserify": {
    "transform": [
      ["evalify", { "files": ["**/service.js"] } ]
    ]
  }
}

how to do authentication

authentication is answers the question of who you are.

here's an example of how to do this in vas, stolen stolen from holodex/app/dex/user/service:

(where config.tickets corresponds to an instance of ticket-auth)

const Route = require('http-routes')

const service = {
  name: 'user',
  manifest: {
    whoami: 'sync'
  },
  authenticate: function (server, config) {
    return (req, cb) => {
      config.tickets.check(req.headers.cookie, cb)
    }
  },
  methods: function (server, config) {
    return { whoami }

    function whoami () {
      return this.id
    }
  },
  handlers: (server, config) => {
    return [
      Route([
        // redeem a user ticket at /login/<ticket> and set cookie.
        ['login/:ticket', function (req, res, next) {
          config.tickets.redeem(req.params.ticket, function (err, cookie) {
            if(err) return next(err)
            // ticket is redeemed! set it as a cookie, 
            res.setHeader('Set-Cookie', cookie)
            res.setHeader('Location', '/') // redirect to the login page.
            res.statusCode = 303
            res.end()
          })
        }],
        // clear cookie.
        ['logout', function (req, res, next) {
          res.setHeader('Set-Cookie', 'cookie=;path=/;expires=Thu, 01 Jan 1970 00:00:00 GMT;')
          res.setHeader('Location', '/') // redirect to the login page.
          res.statusCode = 303
          res.end()
        }],
        // return current user. (for debugging)
        ['whoami', function (req, res, next) {
          res.end(JSON.stringify(req.id) + '\n')
        }]
      ])
    ]
  }
}

install

npm install --save vas

inspiration

license

The Apache License

Copyright © 2016 Michael Williams

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.