Node.js

node.js
Node.js logo.svg
Original author(s) Ryan Dahl
Developer(s) Node.js Developers, Joyent, Github Contributors
Initial release May 27, 2009 (2009-05-27)[1]
Stable release 0.12.0 / February 6, 2015 (2015-02-06)[2]
Preview release 0.11.15 / January 20, 2015 (2015-01-20)[3]
Development status Active
Written in C, C++, JavaScript
Operating system OS X, Linux, Solaris, FreeBSD, OpenBSD, Microsoft Windows (older versions require Cygwin), webOS
Type Event-driven networking
License MIT
Website nodejs.org

Node.js is an open source, cross-platform runtime environment for server-side and networking applications. Node.js applications are written in JavaScript, and can be run within the Node.js runtime on OS X, Microsoft Windows, Linux, FreeBSD, and IBM i.

Node.js provides an event-driven architecture and a non-blocking I/O API that optimizes an application's throughput and scalability. These technologies are commonly used for real-time web applications.

Node.js uses the Google V8 JavaScript engine to execute code, and a large percentage of the basic modules are written in JavaScript. Node.js contains a built-in library to allow applications to act as a Web server without software such as Apache HTTP Server or IIS.

Node.js is gaining adoption as a server-side platform[4] and is used by Microsoft,[5][6] Yahoo!,[7] Walmart,[8] Groupon,[9] SAP,[10] LinkedIn,[11][12] Rakuten, PayPal,[13][14] Voxer,[15] and GoDaddy.[16]

History

Ryan Dahl, creator of Node.js

Node.js was invented in 2009 by Ryan Dahl, and other developers working at Joyent.[17] Node.js was created and first published for Linux use in 2009. Its development and maintenance was spearheaded by Ryan Dahl and sponsored by Joyent, the firm where Dahl worked.[18]

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.[19]

It garnered international attention after its debut at the inaugural European JSConf on November 8, 2009.[20][21][22] Dahl presented Node.js, which combined Google's V8 JavaScript engine, and event-loop, and a low-level I/O API.[17] The project received a standing ovation, and has since then been met with unprecedented growth, popularity and adoption.[17]

In 2011, a package manager was introduced for Node.js library, called npm. The package manager allows publishing and sharing of open-source Node.js libraries by the community, and simplifies installation, updating and un-installation of libraries.[17]

In June 2011, Microsoft partnered with Joyent to create a native Windows version of Node.js.[23] The first Node.js build to support Windows was released in July.

In January 2012, Dahl stepped aside, promoting coworker and npm creator Isaac Schlueter to manage the project.[24]

In January 2014, Schlueter announced Timothy J. Fontaine would be Node.js's new project lead.[25]

In December 2014, Fedor Indutny started io.js, a fork of Node.js. Due to internal conflict over Joyent's governance, io.js was created as an open governance alternative with a separate technical committee.[26]

Overview

Node.js allows creation of web servers and networking tools, using JavaScript and a collection of "modules" that handle various core functionality.[17][27][20][28][29] Modules handle File system I/O, Networking (HTTP, TCP, UDP, DNS, or TLS/SSL), Binary data (buffers), Cryptography functions, Data streams, and other core functions.[30][17][28] Node's modules have a simple and elegant API, reducing the complexity of writing server applications.[17][28]

Frameworks can be used to accelerate the development of applications, and common frameworks are Express.js, Socket.io and Connect.[17][31] Node.js applications can run on Microsoft Windows, Unix and Mac OS X servers. Node.js applications can alternatively be written with CoffeeScript (a more readable form of JavaScript), or Microsoft TypeScript (a strongly-typed form of JavaScript).[32]

Node.js is primarily used to build network programs such as web servers, and is similar to PHP or Python.[27] The biggest difference between PHP and Node.js, is that PHP is a blocking language (commands execute only after the previous command has completed), while Node.js is a non-blocking language (commands execute in parallel, and use callbacks to signal completion).[27]

Node.js brings event-driven programming to web servers, enabling development of fast web servers in JavaScript.[17] Developers can create highly scalable servers without using threading, by using a simplified model of event-driven programming that uses callbacks to signal the completion of a task.[17] Node.js was created because concurrency is difficult in many server-side programming languages, and leads to poor performance.[20] Node.js connects the ease of a scripting language (JavaScript) with the power of Unix network programming.[17]

Node.js is built on the Google V8 JavaScript engine, because:[20]

Thousands of open-source libraries have been built for Node.js, and can be downloaded for free from the node package manager website. Node.js has a developer community centered on two mailing lists and the IRC channel #node.js on freenode. The community gathers at NodeConf, an annual developer conference focused on Node.js.[33]

Technical

Dahl originally had the goal of creating Web sites with push capabilities such as those seen in Gmail[examples needed]. After trying solutions in several other programming languages, he chose JavaScript because of the lack of built-in support for streams, filesystem access, or binary objects.[34] This allowed him to define a convention of asynchronous, event-driven I/O.[35]

JavaScript has no unified API for I/O, allowing the developers to think about the best way to implement a modern I/O interface[unbalanced opinion]. In Node.js, the fact that all I/O is implemented in an asynchronous and non-blocking[further explanation needed] way, combined with a single-threaded event-based loop, presented a novel[dubious – discuss] way to implement real-time web applications. Node.js can therefore keep many connections alive transparently without having to reject new incoming connections[further explanation needed].

Node.js applications are designed to maximize throughput and efficiency[not specific enough to verify] using non-blocking I/O and asynchronous events[further explanation needed]. It is commonly used for real-time web applications due to its asynchronous nature. Node.js internally uses the Google V8 JavaScript engine to execute code, and a large percentage of the basic modules are written in JavaScript. Node.js contains a built-in asynchronous I/O library for file, socket, and HTTP communication, which allows applications to act as a Web server without software such as Apache HTTP Server or IIS.

Node.js is influenced by other models, such as the Ruby Event Machine and Python's Twisted model. The difference between alternatives is the implementation of the event loop as a language instead of a library[neutrality is disputed]. Unlike traditional models, which use blocking calls[not specific enough to verify], Node.js does not have event-loop calls[clarification needed]. Instead, Node.js enters the loop after executing the script[clarification needed], based on how JavaScript works. Ruby's Mongrel Web server was another source of inspiration.[36]

Node.js applications usually run single-threaded, although multi-threaded execution is supported on Node.js 0.10+ from JXcore. Node.js is based on single-threaded execution, although Node.js uses multiple threads for file and network events.

Node.js can be compiled locally or downloaded as a pre-compiled binary. Applications are executed from the command line with the command: "node <application name>.js"

Threading

Node.js operates on a single thread, using non-blocking I/O calls, allowing it to support tens of thousands of concurrent connections, without incurring the cost of thread context-switching. The design of sharing a single thread between all the requests means it can be used to build highly concurrent applications. The design goal of a Node.js application is that any function performing I/O must use a callback.

A downside of this approach is that Node.js doesn't allow scaling with the number of CPU cores of the machine it is running on without using an additional module such as pm2.

V8

V8 is the JavaScript execution engine built for Google Chrome, open-sourced by Google in 2008. Written in C++, V8 compiles JavaScript source code to native machine code instead of of interpreting it in real time.

Node.js contains libuv to handle asynchronous events. V8 provides the run-time for JavaScript. Libuv is an abstraction layer for network and file system functionality on both Windows and POSIX-based systems like Linux, Mac OS X and Unix.

The core functionality of Node.js resides in a JavaScript library. The Node.js bindings, written in C++, connect these technologies to each other and to the operating system.

Package management

npm is the pre-installed package manager for the Node.js server platform. It is used to install Node.js programs from the npm registry. By organizing the installation and management of third-party Node.js programs, it helps developers build faster. npm is not to be confused with the CommonJS require() statement. It is not used to load code: instead, it is used to install code and manage code dependencies from the command line. The packages found in the npm registry can range from simple helper libraries like underscore.js to task runners like Grunt.

Unified API

Node.js combined with a browser, a document DB (such as MongoDB or CouchDB) and JSON offers a unified JavaScript development stack. With the increased attention to client-side frameworks and the adaptation of what were essentially server-side development patterns like MVC, MVP, MVVM, etc., Node.js allows the reuse of the same model and service interface between client-side and server-side.

Event loop

Node.js registers itself with the operating system so that it is notified when a connection is made. When a connection is made, the operating system will issue a callback. Within the Node.js runtime, each connection is a small heap allocation. Traditionally, relatively heavyweight OS processes or threads handled each connection. Node.js, however, uses an event loop, instead of processes or threads, to scale to millions of connections happening at the same time[citation needed]. In contrast to other event-driven servers, Node.js's event loop does not need to be called explicitly. Instead callbacks are defined, and the server automatically enters the event loop at the end of the callback definition. Node.js exits the event loop when there are no further callbacks to be performed.

Tools

Desktop IDEs
Online code editors
Runtimes and debuggers
Application Performance Management
Frameworks

Alternatives

io.js

io.js
Original author(s) Fedor Indutny
Developer(s) io.js Developers, Github Contributors
Initial release January 14, 2015 (2015-01-14)[42]
Preview release 1.0.4 / January 24, 2015 (2015-01-24)[2]
Development status Active
Written in C, C++, JavaScript
Operating system OS X, Linux, Microsoft Windows
Type Event-driven networking
License MIT
Website iojs.org

io.js is a fork of Node.js, started in December 2014[26] by a contributor to the Node.js project.[43] It is expected to be marked stable in March 2015.[44] The reason for forking away from Node.js, was that the authors wanted a project outside corporate governance, and have therefore created an "open governance" system consisting of a technical committee which the authors are part of.[43]

Like Node.js, it is an open source, cross-platform runtime environment for server-side and networking applications. io.js applications are written in JavaScript, and can be run within the io.js runtime on OS X, Microsoft Windows, and Linux. io.js provides an event-driven architecture and a non-blocking I/O API that optimizes an application's throughput and scalability.

io.js uses the Google V8 JavaScript engine to execute code, but unlike Node.js[45] plans are to keep it up–to–date with latest releases of this engine.[44]

Other languages

Similar environments available for other programming languages include:

See also

Portal icon Free software portal

References

  1. ^ https://github.com/joyent/node/tags?after=v0.0.4. Retrieved 2 August 2014.  Missing or empty |title= (help)
  2. ^ a b "v0.12.0 Stable". Retrieved 2 February 2015. 
  3. ^ "Node.js releases". Retrieved 23 January 2015. 
  4. ^ Industry Usage, Node.js Website
  5. ^ "Here's why you should be happy that Microsoft is embracing Node.js". The Guardian. November 9, 2011. Retrieved May 10, 2012. 
  6. ^ "WebMatrix - Front End Web Developers take note (ASP.NET, PHP, node.js and more)". Retrieved 2 August 2014. 
  7. ^ http://developer.yahoo.com/blogs/ydn/posts/2011/11/yahoo-announces-cocktails-%E2%80%93-shaken-not-stirred/. Retrieved 2 August 2014.  Missing or empty |title= (help)
  8. ^ "Why Walmart is using Node.js". VentureBeat. January 24, 2012. Retrieved May 10, 2012. 
  9. ^ Geitgey, Adam (30 October 2013). "I-Tier: Dismantling the Monoliths". Groupon. Retrieved 30 April 2014. 
  10. ^ "SAP AppBuilder". SAP. March 10, 2014. Retrieved March 10, 2014. 
  11. ^ "You'll never believe how LinkedIn built its new iPad app". VentureBeat. May 2, 2012. Retrieved May 10, 2012. 
  12. ^ http://engineering.linkedin.com/nodejs/blazing-fast-nodejs-10-performance-tips-linkedin-mobile. Retrieved 2 August 2014.  Missing or empty |title= (help)
  13. ^ "Clash of the Titans: Releasing the Kraken, NodeJS @paypal". fluentconf.com. May 28, 2013. Retrieved September 11, 2013. 
  14. ^ "All such companies and their products in which Node.js is used". Retrieved 2 August 2014. 
  15. ^ The Node Ahead: JavaScript leaps from browser into future, The Register, 1 Mar 2011
  16. ^ Why GoDaddy’s Nodejitsu deal is great for Node.js, VentureBeat, 10 Feb 2015
  17. ^ a b c d e f g h i j k Professional Node.js: Building Javascript Based Scalable Software, John Wiley & Sons, 01-Oct-2012
  18. ^ Alex Handy (2011-06-24). "Node.js pushes JavaScript to the server-side". SDTimes. Retrieved 2011-09-04. 
  19. ^ Harris, Amber (April 1, 2012). "The Birth of Node: Where Did it Come From? Creator Ryan Dahl Shares the History". Devops Angle. Retrieved 26 October 2013. 
  20. ^ a b c d Sams Teach Yourself Node.js in 24 Hours, Sams Publishing, 05-Sep-2012
  21. ^ "Ryan Dahl at JSConf EU 2009". 
  22. ^ "Ryan Dahl at JSConf EU 2009 Video". 
  23. ^ "Porting Node to Windows". Retrieved 2 August 2014. 
  24. ^ Dahl, Ryan. "New gatekeeper". Retrieved 26 October 2013. 
  25. ^ Schlueter, Isaac (January 15, 2014). "The Next Phase of Node.js". Retrieved 21 January 2014. 
  26. ^ a b Krill, Paul (Dec 4, 2014). "Why io.js Decided to Fork Node.js". JavaWorld. Retrieved Dec 15, 2014. 
  27. ^ a b c Node.js for PHP Developers, O'Reilly Media, Inc., 2013
  28. ^ a b c Node.js Essentials, Packt Publishing, 09-Sep-2014
  29. ^ Smashing Node.js: JavaScript Everywhere, John Wiley & Sons, 14-Aug-2012
  30. ^ Modules, Nodejs Website
  31. ^ Express.js Guide: The Comprehensive Book on Express.js, Azat Mardan, 28-May-2014
  32. ^ CoffeeScript on Node.js, O'Reilly Media, Inc., 15-Apr-2013
  33. ^ Finley, Klint (April 7, 2011). "NodeConf Schedule Announced". ReadWriteHack. Retrieved 2 August 2014. 
  34. ^ Pasquali, S. (2013). Mastering node.js. Olton, Birmingham, GBR: Packt Publishing Ltd., p. 9
  35. ^ Hughes-Croucher, Tom; Wilson, Mike (2012). Up and Running with Node.js. Up and Running (1st ed.). Sebastopol: O'Reilly. p. vii. ISBN 978-1-4493-9858-3. I was concerned about the ability to program advanced push features into the website like I had seen in Gmail 
  36. ^ Synodinos, Dio (December 13, 2010). "Deep inside Node.js with Ryan Dahl". InfoQ. Retrieved 26 October 2013. 
  37. ^ "Node.js Tools for Visual Studio". Codeplex. Retrieved 2 August 2014. 
  38. ^ "Bergius: Flowhub and the GNOME Developer Experience". LWN.net. 2014-05-02. Retrieved 2014-05-24. 
  39. ^ Mike Kopp (2014-11-27). "There’s a new kid in town: node.js monitoring". blog.ruxit.com. Retrieved 2014-11-28. 
  40. ^ Node.js Framework Comparison: Express vs. Koa vs. Hapi, AirPair
  41. ^ 13 fabulous frameworks for Node.js, InfoWorld
  42. ^ "Release notes for this version". Retrieved 2 February 2015. 
  43. ^ a b Q&A: Why io.js decided to fork Node.js, Infoworld Tech Watch
  44. ^ a b Mikeal, Rogers (January 28, 2015). "State of io.js". Retrieved 2 February 2015. 
  45. ^ Ben Noordhuis (Nov 12, 2014). "Issue 3692: function suddenly becomes undefined". V8 JavaScript Engine Issues. Retrieved 2 February 2015. 

Further reading

External links

Code analysis
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Debuggers
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fonte: https://web.archive.org/web/20150323131503/https://en.wikipedia.org/wiki/Node.js