A brief intro to nodejs
Jay LJLU from Evenex team

• Built on Chrome’s JavaScript runtime
• Event-driven
• Non-blocking IO
• Easily building Fast, scalable network application

Built on Chrome’s JavaScript runtime
• Server side, V8 engine
• Fast
• ECMA 5 standards compliance
• “api bits that aren’t considered safe to use in a
web setting but are built in to node’s V8
engine.”
• Choosing JS over C,Lua,Haskell,Ruby

Event-driven
• EventEmitter
• Event loop in libev
• Functional programming in JS
– First-class functions
– Closure
• Used across all core modules

Non-blocking IO 1/2
• “I/O is expensive”

Non-blocking IO 2/2
• Long polling (chatroom/whiteboard), socket.io
• Streaming, (Byte)Buffer
• Blocking vs non-blocking
• Context switch is expensive
• C10K problem
• Share same architecture with nginx

Easily building fast, scalable network
application 1/2
• Easy
– “NodeJs is the new Java”
– Fancy core library
– No compile, fast iteration

Easily building fast, scalable network
application 2/2
• One language rule all. MEAN Stack.
• “web”=>“network”
• TJ Holowaychuk

Engineering
• NPM
• IDE
• Deployment
• Coding style
• Testing
• Debugging
• When to use nodejs
• Companies using NodeJs

Engineering
NPM
• Node packaged modules
– https://npmjs.org
– Now part of core node
– Easily manage dependencies
– package.json

Engineering
IDE
• WebStorm
– Commercial license
– Truly IDE , good for beginner
• Sublime text
– Free to use
– Syntax highlight
– Code template/completion
– Node plugin

Engineering
deployment
• Single thread, single process
– Utilize my 8 cores CPU ? (new cluster module)
• Integrate with legacy services, not replace
– Consumes JSON RESTful services
• Run behind Nginx
– Not stable enough to be a web server
• Hosting

Engineering
coding style
• Callback hell
– Async.js to rescue
• err as first argument
– Handle error first !
• Extending prototype
– Do not extend the prototypes of any objects, especially
native ones

Engineering
Testing
• Mocha
– Fancy reports
– BDD, TDD
– Timeout – good for asyc
– Runs in browser as well
• CI : grunt+jenkins
– Alt : Travis CI https://github.com/travis-ci

Engineering
debugging
• Chrome developer tool
– Eclipse based
• Node-inspector
– Browser based

Engineering
when to use nodejs
• When to use Node.js:
• Use Node.js to:
• Build a (soft) real-time social app like Twitter or a chat app.
• Build high-performance, high I/O, TCP apps like proxy servers, PaaS, databases, etc.
• Build backend logging and processing apps.
• Build great CLI apps similar to vmc-tool, and build tools such as ant or Make.
• Add a RESTful API-based web server in front of an application server.
• When NOT to use Node.js:
• Node.js is not suitable for every application:
• Mission-critical (hard) real-time apps like heart monitoring apps or those that
are CPU-intensive.
• For simple CRUD apps that don’t have any real-time or high-performance needs,
Node.js does not provide much of an advantage over other languages.
• Enterprise apps that might need some specific libraries for which there may not be
a Node.js library yet. (However, you could build a polyglot app that uses Java in
conjunction to Node.js to help with libraries.)

Companies using NodeJs
• LinkedIn, mobile webapp
• Ebay, data retrival gateway
• Github, for downloads
• Dow Jones & Company, for WJS social site
• PayPal (moving every product & every site)

Refs and links
• http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/
• http://www.slideshare.net/the_undefined/nodejs-best-practices-10428790
• http://www.slideshare.net/the_undefined/nodejs-a-practical-introduction-v2
• http://www.slideshare.net/oscarrenalias/nodejs-for-architects-openslava-2013

Getting started !!
• git checkout https://github.com/joyent/node
• ./configure && make && sudo make install
• vi example.js
• node example.js

Thanks !
• 刘立杰 Jay LJLU

More interesting…
• CoffeeScript
• Twitter Bower
• Yeoman/grunt
• phantomjs