node.js - Fast event based web application development

node.js - Fast event based web application development

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  node.js Fast eventbased web application development Wien, 7. April 2011 Gerhard Hipfinger
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  What is node.js?A JavaScript runtime Based on Googles V8 JavaScript engine High performance async event handling Module system, I/O system bindings, supports all common network protocols
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  Availability Available onall major platforms and on Windows too (via Cygwin or MinGW)
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  Module Management Youwant to use module management as there are many available! Over 1100 NPM is your friend curl http://npmjs.org/install.sh | sh npm install express
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  Obligatory Hello,World! console.log('Hello, node.js World!'); > node hello.js Hello, node.js World! Create file hello.js with the content: Than type:
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  Design Goals Onlya small core library Extensible module system Non blocking I/O As close to system calls as possible
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  Non Blocking I/OFirst we look at traditional blocking I/O I/O is serialized and the execution time is sum(opA, opB) var a = getSomethingFromDatabase(); c onsole.log(a); v ar b = getSomethingFromDatabase(); console.log(b);
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  Non Blocking I/OgetSomethingFromDatabase(paramA, function(result) { console.log(result); }); getSomethingFromDatabase(paramB function(result) { console.log(result); }); Both queries are handled in an event queue and don't block each other Execution time is MAX(op1,op2)
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  Non Blocking I/Onode.js uses epoll, kqueue or whatever is available at the underlying operating system So I/O does not waste your CPU cycles No busy waiting! Thread pool is used for everything else
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  (No) Threads Therest of your app is single threaded Easy programming model but is not useful for all kinds of apps
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  Your Webserver in6 LOC var http = require('http'); http.createServer( function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }).listen(8888, "127.0.0.1"); console.log('Server running at http://127.0.0.1:8888/'); Pretty simple, isn't it?
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  Ever needed topoll for filechange? var fs = require('fs'); fs.watchFile(__filename, function() { console.log('I was changed!'); process.exit(0); });
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  So what canI do with node.js node.js is great for all I/O centric tasks Nearly all network apps are I/O centric (web or application server, socket server and so on)
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  node.js is goodfor... Web applications Streaming Unix tools (yeah, you can start your files with #!/usr/bin/node )
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  Don't use itfor... CPU intense apps with few I/O Apps that need huge memory (V8 has a 1.9G limit) Multiple cores need multiple processes (single threaded)
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  Modules you willfall in love with Express Socket.IO Cradle (CouchDB module)
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  There is roomfor improvement Tool support Debugging Error reporting Windows support (when you realy want a Windows server) XML support
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  JavaScript Support NodeJS contains CommonsJS EcmaScript5 Usable node API
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  Integration Great supportfor NonSQL stores: CouchDB, Redis But you still can use your RDB -> modules for all major databases
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  Resources http://nodejs.org/ https://github.com/joyent/node/wiki/moduleshttp://expressjs.com/ http://socket.io/ You will need a good JavaScript understanding http://oreilly.com/catalog/9780596517748
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  Gerhard Hipfinger openForceInformation Technology GesmbH Dresdner Str. 108 / 3. Stock / Top 11 1200 Wien TEL +43 1 3191775 FAX +43 1 3191775-20 http://openforce.com