Node.js and Socket.io Demo in JSCafe

presentation

Presentation is here!!

http://goo.gl/46dk3

Who are you ?

Working at :

Twitter : @yosuke_furukawa

Blog : from scratch

Community :

What is Node.js ?

Javascript on *** (Server, Arduino, Rapsberry PI, etc.)

Not only web browser !!!

Keywords

1. Non-Blocking IO
2. Callbacks
3. Single Thread
4. process.nextTick
5. Event Emitter

Non Blocking I/O

printLine("Please input your name: ");
var name = getLine();
var result = db.save(name);
if (result === 'ok')
  printLine("saved!");

reference note: pseudo code.

Non Blocking I/O

printLine("Please input your name: ");
// non blocked this line, go next.
var name = getLine();
// name is *undefined*.
var result = db.save(name);
// result is always not 'ok' !!!
if (result === 'ok')
  printLine("saved!");

Callbacks

printLine("Please input your name: ", function(){
  getLine(function(err, name) {
    db.save(name, function(err, r) {
      if (r === 'ok')
        printLine("saved!");
    });
  });
});

single thread

printLine("Please input your name: ", function(){
  getLine(function(err, name) {
    db.save(name, function(err, r) {
      if (r === 'ok')
        printLine("saved!");
      // add new code
      db.getAll(function(err, names) {
        names.forEach(function(name) {
          printLine(name);
        });
      });
    });
  });
});

single thread

printLine("Please input your name: ", function(){
  getLine(function(err, name) {
    db.save(name, function(err, r) {
      if (r === 'ok')
        printLine("saved!");
      db.getAll(function(err, names) {
        // if num of names is huge.
        // stop all tasks !!!
        names.forEach(function(name) {
          printLine(name);
        });
      });
    });
  });
});

process.nextTick

printLine("Please input your name: ", function(){
  getLine(function(err, name) {
    db.save(name, function(err, r) {
      if (r === 'ok')
        printLine("saved!");
      db.getAll(function(err, names) {
        names.forEach(function(name) {
          // Dont stop all task.
          process.nextTick(function(){
            printLine(name);
          });
        });
      });
    });
  });
});

Crazy callbacks...

printLine("Please input your name: ", function(){
  getLine(function(err, name) {
    db.save(name, function(err, r) {
      if (r === 'ok')
        printLine("saved!");
      db.getAll(function(err, names) {
        names.forEach(function(name) {
          process.nextTick(function(){
            printLine(name);
          });
        });
      });
    });
  });
});

Event Emitter!!

var event = new EventEmitter();
event.on('hoge', function(arg) {
  printLine(arg);
});
event.emit('hoge', 'fuga');
// print fuga

Event Emitter!!

printLine("Please input your name: ", function(){
  getLine(function(err, name) {
    db.emit('save', name);
  });
});
db.on('save end', function(err, r) {
  if (r === 'ok')
    printLine("saved!");
  db.emit('getAll');
});
db.on('getAll end', function(err, names){
  names.forEach(function(name) {
    process.nextTick(function(){
      printLine(name);
    });
  });
});

I dont have time to talk all keywords.

If you have an interest, you would read these to be better.

Node.js Patterns and Opinions

Node.jsとは何か(Ryan Dahlの講演)

I guess 10 minutes left...

Play with Node!!!!

Hello JSCafe on HTTP

easy to write!!

var http = require('http');
http.createServer(function(req, res){
  res.end("<h1>hello jscafe.</h1>");
}).listen(3000);

Hello JSCafe on chat with you.

node.js chat!!

var net = require('net');
var clients = [];
var server = net.createserver(function(sock){
  sock.on('end', function(){
    sock.emit('data', "goodbye!! \n");
    clients.splice(clients.indexof(sock), 1);
  });
  sock.resume();
  clients.foreach(function(i){
    sock.pipe(i, {end:false}).pipe(sock, {end:false});
  });
  clients.push(sock);
});
server.listen(1337);

Hello JSCafe on chat with you.

please access

$ nc <IP address> 1337

I guess my greetings reach you.

Node is fun??

"I'm Fan!!"

I guess 5 minutes left....

Socket.io

Socket.io is a realtime library for Node.js

Socket.io uses WebSocket, long polling, Adobe flash socket

So Socket.io supports many kinds of browsers!!!

1. IE 5.5+
2. Safari 3+
3. Google Chrome 4+
4. Firefox 3+
5. Opera 10.61+

Actually, this slide uses Socket.io :)

A lot of demo use Socket.io

• chat
• realtime paint
• presentation tool

Google "socket.io chat/paint/presentation"

Socket.io is easy to use!!!

var io = require('socket.io').listen(3000);
io.sockets.on('connection', function(socket) {
  socket.on('message', function(message) {
    // broadcast
    io.sockets.emit('message', message);
  });
});

Socket.io + Webhook

Summary

• Node.js is fun.
• Socke.io is also fun.
• We are fan.

DeNA NEEDS YOU!!!

• JavaScript Engineer
• Noder
• Designer
• Join us!!!!