dispatchington

Trie-based URL and Method Routing for Node.js

Dispatchington

Dispatchington is a trie-based URL and method router for Node.js based on routington. It can almost be used as a drop-in replacement. For information on its motivations, read about The Imperfections of Express.

When should you use this?

  • Want your server to conform to HTTP specs
  • Want to decouple your app away from Connect/Express
  • Prefer a more modular routing framework
  • Prefer explicit routing
  • You repeat a lot of route definitions
  • You want structure to your URL routes - routes are stored in a branch tree
  • Supports the OPTIONS method automatically.
  • Supports 405 Method Not Allowed automatically.
  • Supports 501 Not Implemented automatically, assuming you use the middleware.
  • Allows you to "define" middleware stacks for easy re-use.
  • Faster as it uses string matching instead of regular expression matching whenever possible.

See /benchmark for the benchmark test. The take away of this benchmark isn't that Dispatchington is faster at routing, but that its performance is more precise. In other words, it "scales" with the number and complexity of routes.

Note that these benchmarks are not comprehensive and that the differences in speeds are due to more just the route being matched.

Route Express Dispatchington
/ 10804 req/s 10703 req/s
/discussion/:id/comment/:id/new 8862 req/s 10329 req/s
/404 9294 req/s 10493 req/s
var dispatchington = require('dispatchington')
var router = dispatchington()

To mount the middleware:

var app = express()
app.use(router.implementedMethods)
// static stuff 
// cookie stuff 
// session stuff 
app.use(router.dispatcher)
// 404 handler 
// error handler 

If you're not using Express or Connect, it will still work:

var dispatcher = router.dispatcher
var methods = router.methods
 
// ... 
// Define routes 
// ... 
 
http.createServer().on('request', function (reqres) {
  if (!methods[req.method.toLowerCase()]) {
    res.statusCode = 501
    res.end('Not Implemented')
    return
  }
 
  dispatcher(function (reqresnext) {
    if (err) {
      res.statusCode = err.status || 500
      res.end(err.message || 'Internal Server Error')
      return
    }
 
    // If this point is reached, 
    // no route has been matched 
    res.statusCode = 404
    res.end('Not Found')
  })
}).listen(process.env.PORT || 80)
router.define('compress', connect.compress())
router.define('session', [
  connect.cookieParser(),
  connect.cookieSession()
])

You will define middleware stacks which will then be referrable by name. For example:

router.get('/', 'compress', 'session')

is equivalent to all of the following:

router.get('/', connect.compress(), connect.cookieParser(), connect.cookieSession())
router.get('/', connect.compress(), [
  connect.cookieParser(),
  connect.cookieSession()
])
router.get('/', [
  connect.compress()
  connect.cookieParser(),
  connect.cookieSession()
])

The idea is that you turn your middleware stacks into legos. You can define them early in your app, then re-use them throughout your routes without require()ing each of them from an external "common" module. It will also make your routes much more readable as, ideally, it could look something like this:

router.get('/',
  'compress',
  'cache if visitor',
  'accept html only',
  'retrieve session',
  'retrieve user',
  'check if allowed',
  'parse body',
  handler
)
 
function handler(reqres) {
  res.render('homepage')
}

For information on how the routing strings actually work, view routington's documentation.

There are two ways to create a route. The first is Express' method-first way:

router.get('/things', 'compress', 'session', handler, ...)
router.post('/things', 'compress', 'session', handler, ...)
router.put('/things', 'compress', 'session', handler, ...)

The other is by defining a route, then adding stacks based on the method:

router.route('/things')
.get('compress', 'session', handler, ...)
.post('compress', 'session', handler, ...)
.put('compress', 'session', handler, ...)

In both versions, you can define multiple routes at the same time using an array:

router.route(
  '/things',
  '/thing/:id'
)
.get('compress', 'session', handler, ...)
.post('compress', 'session', handler, ...)
.put('compress', 'session', handler, ...)

If you define a route like so:

router.get('/thing/:id', handler)

You can retrieve the value of id just like in Express:

function handler(reqresnext) {
  req.id = req.params.id
  next()
}

The trie, specifically the routington instance, is accessible at router.trie. You can manipulate it however you'd like. View its documentation for more information.

  • Wildcard routes are not supported. The purpose of this router is to make it easier for you to be explicit.
  • app.all is not supported. Simply define a stack and use it in every method. npm install methods for a list of all possible methods.
  • Regular expressions (as a variable type) are not supported as input arguments. If you want to use regular expressions, just stick with Express' router.

WTFPL

© Jonathan Ong 2013

me@jongleberry.com

@jongleberry