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

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Me (@sh1mmer)

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

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Internet?

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She’s called Eleanor

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More features More users More devices More data

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Stuff Cost

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How do we cope with the increase in demand?

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Internet Applications

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How about search?

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Browser Spidering Server Web Sites

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Would take forever!

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Browser Front-end Server Database Computation

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Client → Server Computation Batch Computing

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Client → Server Server → DB Computation Computation Internet Computing

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“Traditional” Approach

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Server

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Request

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FULL

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Event-driven Approach

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Request Place- holder

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Shared Work Resources

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Welcome to Node.js

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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

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$Enki:~ $ node

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

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> 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:~ $

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

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

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

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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

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

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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

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Why is Node.js suited to Internet Apps?

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What is the event loop?

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Multi-tasking, one thing at a time.

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

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

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var http = require('http'); server = http.createServer(); server.on('request', function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); 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

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

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var http = require('http'); server = http.createServer(); server.on('request', function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); 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. *

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

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var http = require('http'); server = http.createServer(); server.on('request', function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); 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

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var http = require('http'); server = http.createServer(); server.on('request', function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }); 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.)

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Why non-blocking matters

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Event Loop vs. Threads

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//node.js style JavaScript query = mysql.query('SELECT * FROM data'); query.on(‘result’, function(result) { for(var i=0;i

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//threaded style JavaScript result = mysql.query('SELECT * FROM data'); for(var i=0;i

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var x = "I am a string" ~1ns Running 1 instruction 2ns Data from l1 cpu cache 5ns Data from l2 cpu cache 80ns Data from ram

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Server mySQL query result

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result = mysql.query('SELECT * FROM data'); ~100ms Time to run a query in database 50ms Time to roundtrip query over the network

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Local variable

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Remote operation

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Cat 100 Blue Whales

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Blocking is as bad as stopping

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Threading wastes memory for a long time because of programming style

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2mb PHP 8gb ram 8000/2 = 4000 ~4000 users per machine

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

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Apache vs NGINX concurrency × reqs/sec http://blog.webfaction.com/a-little-holiday-present

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Apache vs NGINX concurrency × memory http://blog.webfaction.com/a-little-holiday-present

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

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Demo

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Thanks!

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Follow me @sh1mmer Tom Hughes-Croucher @sh1mmer