A language for the Internet: Why JavaScript and Node.js is right for Internet Application

A language for the
Internet
Why JavaScript and Node.js is right for
Internet Applications

Tom Hughes-Croucher
@sh1mmer

Scalable Server-Side Code with JavaScript

Node Up and Running

Tom Hughes-Croucher

More features
More users
More devices
More data

How do we cope with
the increase in demand?

Browser

Server

Spidering... The Web

Browser

Front-end
Server

Database

Client → Server

Computation

Client → Server Server → DB

Computation Computation

Node.js?

• Server Side JavaScript runtime
• Built on top of V8 JavaScript engine from
Google Chrome
• Non-blocking I/O APIs
• Easy to extend APIs and modules

$Enki:~ $ node
>3>2>1
false
> true == 1
true
> true === 1
false

> console.log('Hello World');
Hello World
> .help
.clear Break, and also clear the local context.
.exit Exit the prompt
.help Show repl options
> .clear
Clearing context...
> .exit
Enki:~ $

Enki:~ $ node
> var foo = "bar";
> foo;
'bar'
> .clear
Clearing context...
> foo
ReferenceError: foo is not deﬁned
at [object Context]:1:1
at Interface.<anonymous> (repl:98:19)
at Interface.emit (events:27:15)
at Interface._ttyWrite (readline:295:12)
at Interface.write (readline:132:30)
at Stream.<anonymous> (repl:79:9)
at Stream.emit (events:27:15)
at IOWatcher.callback (net:489:16)

var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
}).listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');


//include the http library


}).listen(8124, "127.0.0.1");

//create an http server
//when ‘stuff’ happens call this anonymous function
//listen on port 8124 of the IP 127.0.0.1

})

//when ‘stuff’ happens my function ﬁres
//I get a request object and a response object
//I write to the response object header
//HTTP status 200 and content-type ‘text/plain’
//close the response with the body:
//Hello World


//write Server is running at http://127.0.0.1:8124/
//to the console

Why is Node.js suited
to Internet Apps?

Multi-tasking,
one thing at a time.

server = http.createServer();

server.on('request', function (req, res) {
});

server.listen(8124, "127.0.0.1");


});

server.listen(8124, "127.0.0.1");

Step 1.
Evaluate 'Main'


});

server.listen(8124, "127.0.0.1");

Step 1.
variables: http -> http module
server -> http server

listeners: server.request -> function


*
});

server.listen(8124, "127.0.0.1");

Step 2.
Event Loop


*
});

server.listen(8124, "127.0.0.1");

Step 2.
Do we have active listeners?


Yes! Wait for listeners.


});

server.listen(8124, "127.0.0.1");

Step 3.
Event Calls


});

server.listen(8124, "127.0.0.1");

Step 3.
'request' is called. Since


Call function


});

server.listen(8124, "127.0.0.1");

Step 3.
Loop!
(go to Step 2.)

Breaking the event
loop

EE = require('events').EventEmitter;
ee = new EE();

die = false;

ee.on('die', function() {
die = true;
});

setTimeout(function() {
ee.emit('die');
}, 100);

while(!die) {
}

console.log('done');

var result =
db.query("select * from T");
// use result

"Blocking" is as bad
as stopping

PHP

8mb

8gb ram
8000/8 = 1000
~1000 users per
machine

Node.js
TCP = 2kb
HTTP = 6kb

8gb ram
8000/0.006 = 1.3m
1.3m/2 ~ 650k users

Apache vs NGINX
concurrency × reqs/sec

http://blog.webfaction.com/a-little-holiday-present

Apache vs NGINX
concurrency × memory

http://blog.webfaction.com/a-little-holiday-present

Node.js is designed for
communication, just like
your applications

Thanks!
Questions?

Tom Hughes-Croucher
@sh1mmer

A language for the Internet: Why JavaScript and Node.js is right for Internet Application

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Editor's Notes