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

A language for the Internet Why JavaScript and Node.js is right for Internet ApplicationsTom Hughes-Croucher@sh1mmer

Me(@sh1mmer)

Scalable Server-Side Code with JavaScriptNode Up and Running Tom Hughes-Croucher

A brief aside.A small lecture on biology

The common tree shrew

Diana Monkey

Back to your feature presentation.

Internet?

She’s called Eleanor

More features More usersMore devices More data

Cost Stuff

How do we cope withthe increase in demand?

Internet Applications

How about search?

Browser Server Spidering... The Web

Would take forever!

Browser Front-end ServerComputation Database

Computational ComputingClient → Server Computation

Internet ComputingClient → Server Server → DB Computation Computation

“Traditional” Approach

Server

Request

U L LF

Event-driven Approach

Place-holder

Shared WorkResources

Welcome to Node.js

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

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

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

Enki:~ $ node> var foo = "bar";> foo;bar> .clearClearing context...> fooReferenceError: 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/);

var http = require(http);//include the http library

http.createServer(function (req, res) {}).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

http.createServer(function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn);})//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

console.log(Server running at http://127.0.0.1:8124/);//write Server is running at http://127.0.0.1:8124///to the console

Why is Node.js suited to Internet Apps?

What is the event loop?

Multi-tasking,one thing at a time.

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

var http = require(http);server = http.createServer();server.on(request, function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn);});server.listen(8124, "127.0.0.1");console.log(Server running at http://127.0.0.1:8124/); Step 1. Evaluate Main

var http = require(http);server = http.createServer();server.on(request, function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn);});server.listen(8124, "127.0.0.1");console.log(Server running at http://127.0.0.1:8124/); Step 1. variables: http -> http module server -> http server listeners: server.request -> function

var http = require(http); server = http.createServer();* server.on(request, function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn); }); server.listen(8124, "127.0.0.1"); console.log(Server running at http://127.0.0.1:8124/); Step 2. Event Loop

var http = require(http); server = http.createServer();* server.on(request, function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn); }); server.listen(8124, "127.0.0.1"); console.log(Server running at http://127.0.0.1:8124/); Step 2. Do we have active listeners? listeners: server.request -> function Yes! Wait for listeners.

var http = require(http);server = http.createServer();server.on(request, function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn);});server.listen(8124, "127.0.0.1");console.log(Server running at http://127.0.0.1:8124/); Step 3. Event Calls

var http = require(http);server = http.createServer();server.on(request, function (req, res) { res.writeHead(200, {Content-Type: text/plain}); res.end(Hello Worldn);});server.listen(8124, "127.0.0.1");console.log(Server running at http://127.0.0.1:8124/); Step 3. request is called. Since listeners: server.request -> function Call function

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

Why non-blocking matters

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

What are wewaiting for?

"Blocking" is as bad as stopping

Event Loop vs. Threads

PHP8mb 8gb ram 8000/8 = 1000~1000 users per machine

Node.js TCP = 2kb HTTP = 6kb 8gb ram 8000/0.006 = 1.3m1.3m/2 ~ 650k users

Apache vs NGINXconcurrency × reqs/sechttp://blog.webfaction.com/a-little-holiday-present

Apache vs NGINXconcurrency × memoryhttp://blog.webfaction.com/a-little-holiday-present

Node.js is designed forcommunication, just like your applications

Thanks!

Follow me @sh1mmerTom Hughes-Croucher@sh1mmer

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

by Tom Hughes-Croucher on Mar 29, 2011

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A language for the Internet: Why JavaScript and Node.js is right for Internet Applications — Presentation Transcript