Introduction to Node.js
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This is the slide deck from the popular "Introduction to Node.js" webinar with AMD and DevelopIntelligence, presented by Joshua McNeese. Watch our AMD Developer Central YouTube channel for the replay at https://www.youtube.com/user/AMDDevCentral.
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Introduction to Node.js
- 1. Introduction to Node.js Joshua McNeese Develop Intelligence
- 2. Introductions Hi, my name is Joshua McNeese and I’m a JavaScript programmer.
- 3. Agenda What is Node.js? How does it work? What is it good for? Some cool examples Where can you learn more?
- 4. Node.js history First published in 2009 by Ryan Dahl, sponsored by Joyent Inspired by the file upload bar on Flickr npm introduced in 2011 Microsoft partnered with Joyent in 2011 to provide a native Windows version Dahl stepped aside as project lead in 2012 to pursue new research projects
- 5. The future is bright! After 5 years since its release 3rd most popular project on Github 2 million downloads a month Over 20 million downloads of v0.10+ In use by large brands such as Goldman Sachs, eBay, Conde Nast, Dow Jones, Apple, Yahoo and many more Companies are hiring Since Jan `10, the number of Node.js positions have increased more than 90,000% Interest is high Google search trends have increased year over year, even when other “hot” technologies decline (RoR) or remain the same (Obj-C)
- 6. So what is Node.js? “Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.”
- 7. Uh… what? Unless you are already familiar with real-time application development, this possibly sounds like techno-babble So let’s break that down!
- 8. It’s JavaScript! Code is parsed using Google’s V8 JavaScript engine, originally developed for Chrome The good news is that if you already know JavaScript, learning Node.js is fairly easy The bad news is that it’s not like the front-end JavaScript you are probably familiar with
- 9. It’s event-driven Much like frontend JavaScript, Node.js code executes in an “event loop”
- 10. What is an “Event Loop”? According to MDN: “The Event Loop is a queue of callback functions. When an async function executes, the callback function is pushed into the queue. The JavaScript engine doesn't start continue processing the event loop until the code after an async function has executed.”
- 11. Non-blocking I/O Working hand-in-hand with JavaScript’s asynchronous nature, any I/O is delegated to a separate pool of threads Callbacks to execute once I/O operations are completed are added to the event loop for future execution This is one of the cornerstones of Node’s speed and scalability Why? Because I/O is expensive
- 13. The Node.js way
- 14. NPM Bundled with Node.js, similar to CPAN, PEAR, Ruby gems or Python eggs There’s pretty much a package for everything* Impressive stats: > 104k packages > 146 million downloads last week > 599 million downloads last month Super easy to use: npm install express
- 15. package.json
- 16. Some cool examples A webserver in 5 lines? Preposterous! Query a pooled mysql connection? No problem!
- 17. Streams too? Most I/O is handled by streams, so it’s easy to do things like encrypt, compress or otherwise modify streaming data:
- 18. What is it good for? Node.js is good for lightweight, non-CPU intensive network applications APIs Real-time applications, pub/sub, chat servers Streaming data Proxies Command-line utilities Remember that Node.js is still in “beta”, but can be successfully deployed in production environments
- 19. Where can you learn more? Node.js Info http://nodejs.org http://howtonode.org http://www.npmjs.org http://www.codewars.com http://www.developintelligence.com/catalog/web-development-training/ nodejs Developer Info Learn about future webinars with AMD Developer Central: http://developer.amd.com Watch this webinar replay: www.youtube.com/user/AMDDevCentral Learn when the replay is posted: Follow @AMDDevCentral on Twitter Download this deck: http://www.slideshare.net/DevCentralAMD
- 21. Thank You! See you next time!
Editor's Notes
- 1m I say that jokingly as if this is a support group for embarrased internet engineers, since it used to be that being a “javascript programmer” was an embarrassing thing… but today it is exciting to be a javascript programmer, particularly so with technologies like node.js. 20 years in internet industry Developer for past 100… uh 14 years Using javascript for past 8 years Time is mostly equally divided between node.js and php currently Live in colorado with my wife, son, two cats and dog
- 3m Dahl was inspired to create Node.js after seeing a file upload progress bar on Flickr. The browser did not know how much of the file had been uploaded and had to query the Web server. Dahl desired an easier way.[15] Dahl decided to use the v8 engine due to it being open source, and because there weren’t any viable non-blocking i/o models for javascript in a server context at the time
- 3m Researched by StrongLoop Job stats from Indeed Search stats from Google
- 1m According to the website…
- I thought the coolest thing javascript could do was the canvas element!
- 3m By default, node.js supports ES5, although many of ES6 features can be enabled
- 5m Describe how js executes code sequentially and blocking like front-end javascript, but leverages callbacks to maintain non-blocking overall execution Highlight similarity to frontend javascript’s event loop, using the DOM and browser events
- 3m An event loop is "an entity that handles and processes external events and converts them into callback invocations". So I/O calls are the points at which Node.js can switch from one request to another. At an I/O call, your code saves the callback and returns control to the node.js runtime environment. The callback will be called later when the data actually is available. This is part of the reason why node.js is efficient, in that it uses every opportunity available to continue processing the main event loop, without waiting for long-running threads to complete executing One main difference between node.js’s eventloop vs. other event-driven frameworks like EventMachine for ruby, or twisted for python is that this functionality is transparently part of the runtime, and not a structure built on top of the language. You don’t have to remember to engage the event loop, the node process enters it immediately upon execution, and when there is no longer any callbacks to execute, it exits.
- 4m This pool is managed by libuv, created by Joyent It’s been said: “the largest waste with current programming technologies comes from waiting for I/O to complete”
- 2m A multithreaded server such as apache or tomcat
- 2m No clients waiting on acknowledgement of their request (while they may be waiting on a response!)
- 3m And if there isn’t, go build one! The community loves new packages. Modules can easily be build with javascript, but “heavier” or more proprietary modules can be built with C/C++
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