a1server v1.3.0

a1server

Amplify your server powers!

Next-gen async/await style web server. No need of callback style programming.

All the basic features in one module, routing, static & dynamic pages, REST services and reverse-proxy.

Built-in logger, or use preferred loggers at any time with no code refactoring.

Install express/connect middleware or create your own plugins.

Installation

npm install a1server

1 min Tutorial

Just use the default configuration (port 8080, static files at folder /public and dynamic files at folder /app )

// index.js page
const server = require('a1server')
server.start()

// in terminal: start the server:
//    > cd .../yourApp  
//    > node index
// now open a browser and go to http://localhost:8080

Instead of returning a callback, this module returns a promise after started. The parameter returned is a node http server. Then you could use the node httpServer object to, for instance, attach a web socket.

// index.js page
const server = require('a1server')
server.start().then(httpServer => {}).catch(err => {})

30 min Tutorial (or less)

HINT: check demo application in the module (node_modules/a1server/demo)

starting the server

cd yourApp
node index.js

Configuration

To create a configuration object just add the properties you want to change, and pass the object when calling server.start()

const configuration = {
  port: 80,
  rules: {
    '/': 'landing.html',
    '/intranet/*': '/private/'
  }
}

server.start(configuration)

Available options, and their default values:

{
  ssl: {
    /*key: fs.readFileSync('~/webapp/server.key'),
    cert: fs.readFileSync('~/webapp/server.crt')
    */
  },
  serverName: '',
  welcomePage: 'index.html',
  port: '8080',
  staticFolder: 'public',
  dynamicFolder: 'app',
  rules: { '/': 'index.html' },
  Logger: Logger
}

Routing

When routing you can:

• serve static resources and dynamically generated resources.
• beautify any .html request by removing the extension in the url.
• use plain .js files to process requests, or to create REST APIs.
• reverse proxying requests to other servers you trust in.

Automatic routing

• if the request has an extension (.html, .js, .css, .png, ...), a static file is served. This file should be located at the 'public' directory
• if the request has not extension:
  • if name + ".html" exists, that static file is served.
  • otherwise, a js file is executed in the server, and the result is sent back.

Examples:

• /index.html will serve /public/index.html
• /index will serve /public/index.html, since it exists
• /process will execute /app/process.js

Custom Routing

By adding rules to the configuration. See 'url-pattern' npm module.

const rules = {
  '/': '/index.html', // root page
  '/governance(/\*)': 'http://server1:8081', // proxy to private server
  '/cars(/:id)': '', // REST service
  '/bikes(/:id)': '/other/' // another REST example
}
const configuration = { rules }
server.start(configuration)

Static files

• drop the resources (html, js, css) into the public folder
• request the resources as usual http://server/css/main.css
• As a nice feature, the html files can also be requested without the extension (.html)

Dynamic files

• create a .js file at the app folder
• exports the http methods you want to process (get post put delete)
• implement the exported functions as promises or async functions (or normal functions if no I/O processing). The output of the function should be either a JSON object, a simple type (number, string), or a stream.

IMPORTANT: no callbacks!!!

module.exports = { options, get }

// normal (synchronous) function since no blocking code
function options(request, response, params) {
  return ['GET']
}

// async keyword to avoid blocking
async function get(request, response, params) {
  return database.get(params.id)
}

Creating a REST API

The same as with normal dynamic files. The only difference is to add a rule in the server configuration to be able to extract the 'path' parameters.

Configuration:

const rules = {
  '/cars(/:id)': '', /* /app/cars.js*/
  '/bikes(/:id)': '/inventory/motorbikes' /* /app/inventory/motorbikes.js*/
}

REST service:

The params object is already filled (when the router is processed). These are REST params only, the queryString params can be taken from the request object as usual

Look how the error thrown has the HTTP status code

// file at /app/cars.js

module.exports = { get }

// emulate a database
var cars = {
  '1': { name: 'volvo', engine: '6V' },
  '2': { name: 'seat', engine: '4L' }
}

// in this case (no I/O code) async is not needed
// but in real world cases the methods should be asynchronous
async function get(request, response, params) {
  if (params.id) return await getItem(request, response, params)
  else return await list(request, response, params)
}

async function getItem(request, response, params) {
  const obj = cars[params.id]
  if (!obj) throw(404)
  else return obj
}

async function list(request, response, params) {
  return Object.keys(cars)
}

Plugins

A plugin is a function to be executed before a request has been processed. Plugins can be useful to check if user is authenticated, to insert headers, to log every request to the server, and so on.

request -> is static file?
  |- yes -> send the file
  |- no -> executePlugins -> execute and send the dynamic file

Add plugins the same way as connect or express middleware. The plugins for these applications are also valid here (passport, morgan, cookie-parser, etc...).

For custom plugins, don't forget to add next() or next(err) at the end of the function.

// express-type plugin (middleware)
const morgan = require('morgan')
server.use(morgan('combined'))

// custom plugin
server.use( (req, res, next) => {
  console.log('middleware executed')
  next()
})

WebSockets

The simplest way is by using the ws module, already downloaded with the server.

const WebSocketServer = require('ws').Server

server.start(serverConfiguration)
  .then(httpServer => startWebsocket(httpServer))
  .catch(err => throw err)

  function startWebsocket(httpServer) {
    const wss = new WebSocketServer({ server: httpServer })
    wss.on('connection', ws => {
      ws.on('message', message => {
        ws.send('response from the server')
      })
    })
  }  

Logging

By default no logging module is required (for better performance), but if any of the most popular logging systems (winston, bunyan, log4js, etc...) is a requirement, that logging component can be added in the configuration object.

This way, the developer only need to use the Logger class shipped with the server. If in the future, the real logger is replaced by a new one, no code changes are required, just set the new logger you want to use in the configuration object.

// STEP-1 configure the Logger to use when starting the server
const configuration = {
  Logger: require('winston')
}
server.start(configuration)

// STEP-2 use the standard logger (it behaves as a proxy for the real logger)
// in the js files
const Logger = require('a1server/Logger')
const logger = Logger.getLogger('your-logger-name')
// ...
logger.error(err) // logged by using winston
logger.info('hi')

In development time, the default logger is attached to the console, so use logging instead of console.* methods from the beginning. If you prefer to have no logger output in development mode (for instance, to test requests performance), just configure the Logger to NoOutputLogger.

let Logger = require('a1server/Logger')
Logger.configure(Logger.NoOutputLogger) //no output