GeekCampSG - Nodejs , Websockets and Realtime Web

GeekCampSG - Nodejs , Websockets and Realtime Web

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  Node.js , Socket.io and the Magic Bhagaban Behera
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  What is Node.js? Created by Ryan Dahl ( Joyent ) Command line tool to run Javascript Built on Top of Google’s V8 Javascript Engine Provides Javascript API for Network and File System . Used to create Servers, Networking tools. Event-driven , non-blocking I/O APIs Core written in C/C++ . Supports C/C++ addons. Can handle thousands of concurrent connections with minimal overhead on a single process.
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  What’s the need?
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  Node.js - Features ReallyLean( 8000 lines of C/C++ and 2000 lines of JS ) Exceptionally Fast Easily Scalable
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  Event-Driven Approach Analogy –Bank Reception Analogy - Restaurant
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  The Cost ofIO Accessing RAM ~250 CPU cycles Disk Operations ~41 000 000 CPU cycles Reading a file Writing to a file Network IO ~240 000 000 CPU cycles Database Query HTTP Responses
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  Handling I/O Apacheis multithreaded (depending on conf.) Spawns a thread per request (or process) Each request is in its own "box” Blocking IO result = query('SELECT * FROM ...'); print result.id;
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  The Node way Singlethread for your code ...but, I/O runs in parallel Handle thousands of concurrent connections with a single process Need to be very careful with CPU-intensive code
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  Why JavaScript ? •Single Threaded , Asynchronous • Non blocking IO • Ubiquitous • Massive codebase of libraries • One language to rule them all( Full stack )
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  Hello World ! HellowWorld.js HellowWorld.php setTimeout(function(){ echo(“Hello”); console.log(“World”); sleep(2000); },2000); echo(“World”); console.log(“Hello”);
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  Our own HTTPServer var http= require('http'); var s = http.createServer(function(req,res){ res.writeHead(200,{'content-type' : 'text/plain'}) ; res.end("hello world n"); }) s.listen(8000);
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  Built-in Modules • FileSystem require('fs'); • HTTP Client and Server require('http'); • TCP Sockets require('net'); • Many more: http://nodejs.org/docs/v0.4.8/api/
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  Express makes HTTPeasier • Node's HTTP module is low level. • Express is a simple framework inspired by Sinatra (Ruby). • InstallingExpress: npm install express • Robust verb-based routing app.get('/about', function(req, res) { }); • Templating(with Jade or EJS) • Sessions
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  When to useNode.js ? Realtime Apps Crawlers Single-page Apps Streaming File uploading Online Gaming Collaboration Live Sports Live chat Financial Applications
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  Getting Started Node.js: http://nodejs.org/#download Buildinstructions:http://bit.ly/egLfzu Mac: brew update && brew install node npm, a package manager for Node: curl http://npmjs.org/install.sh | sh Many modules at: http://search.npmjs.org/ Windows support isn't great.
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  Node PAAS NodeJitsu Nodester Joyent Heroku
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  Socket.io
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  Real-time Web
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  History Static Apps Dynamic Apps AjaxApps Real-time Apps
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  HTTP
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  Ajax Polling
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  Long Polling
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  Sockets
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  Websockets / Socket.io Socket.IOaims to make realtime apps possible in every browser and mobile device, blurring the differences between the different transport mechanisms. It's care-free realtime 100% in JavaScript.
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  Show me thecode Visit http://socket.io/#how-to-use for excellent and simple documentation .
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  Contact me ! [email protected]/ @bhoga