spdy.md

SPDY

Koala adds some SPDY support to Koa. Once SPDY becomes an HTTP standard and is baked into node.js, some of these features will be placed in Koa.

this.isSpdy

Check whether SPDY is supported.

app.use(function* (next) {
  if (this.isSpdy) {
    this.push('/some-file.js', {
      filename: __dirname + '/some-file.js'
    });
  }

  yield* next;
})

[yield] this.push([path], options, [priority])

SPDY push a body. This is a wrapper around node-spdy push streams, allowing you to not think about stream acknowledgement, error handling, and file descriptor leaks. spdy-push is used under the hood.

• path - the path of the push stream
• priority: 7 - the priority of the push stream. 0 is highest, 7 is lowest.
• options:
  • path if not set as an argument
  • priority: 7 if not set as an argument
  • body - the body of the stream as a string, buffer, or stream
  • filename - the absolute path of the source file
  • headers - the headers for the stream

Either set options.body or options.filename. The following headers will automatically be set if possible:

• content-length - unless the body is a stream or filename
• content-encoding
• content-type - based on path

Argument order does not matter, so use whatever is convenient.

app.use(function* () {
  this.push({
    path: '/index.js',
    filename: path.resolve('public/index.js'),
    headers: {
      'cache-control': 'public, max-age=999999999999'
    }
  })
})

You may optionally yield this.push(). This yields until the push stream is finished. You may want this to avoid some issues with push streams.

Setup SPDY server

Since node-spdy is optional dependency. You need install it by yourself npm install spdy --save.

SPDY server is compatible with https module and fallback to regular https (for browsers that don't support SPDY yet).

Imagine you're building a single page web site.

app.use(function* () {
    yield this.fileServer.send('index.html');
    if (this.isSpdy) {
        yield this.push('/some-file.js', {
            filename: __dirname + '/some-file.js'
        });
        yield this.fileServer.push('css/all.css'); // or better use fileServer.push
        yield this.fileServer.push('img/logo.png'); // push image resources
        yield this.polyfills.push(); // polyfills support push also
    }
});

var spdy = require('spdy'),
    fs = require('fs');

var server = spdy.createServer({
    key: fs.readFileSync('server.key'),
    cert: fs.readFileSync('server.crt'),
    ca: fs.readFileSync('server.csr')
}, app.callback());

server.listen(3000);

Open chrome(27+) visit https://localhost:3000. Server logs like this:

  <-- GET /
  --> GET / 200 302ms 367b

If you visit with other old browser without spdy support. The logs maybe like this:

  <-- GET /
  --> GET / 200 76ms 367b
  <-- GET /css/all.css
  --> GET /css/all.css 200 16ms 32.73kb
  <-- GET /js/polyfill.js
  --> GET /js/polyfill.js 200 20ms -
  <-- GET /some-file.js
  --> GET /some-file.js 200 15ms -
  <-- GET /img/logo.png
  --> GET /img/logo.png 200 29ms 29.89kb

SPDY can help you reuse http connection. Send more data in one request.

Its goal is to reduce the latency of web pages. --- http://www.chromium.org/spdy

self-signed SSL Certificate

For testing purposes. We need self-signed SSL certificate to boot up SPDY server.

An easily way is install spdy-keys.

var keys = require('spdy-keys');

spdy.createServer(keys, app.callback());

If you want to create keys by yourself. Read How to create a self-signed SSL Certificate ...