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 5.4.1 / January 12, 2016 (2016-01-12)[2]
Development status Active
Written in C, C++, JavaScript
Operating system OS X, Linux, Solaris, FreeBSD, OpenBSD, Microsoft Windows (older versions require Cygwin), webOS, NonStop OS
Type Event-driven networking
License MIT
Website nodejs.org

Node.js is an open-source, cross-platform runtime environment for developing server-side web applications. Node.js applications are written in JavaScript and can be run within the Node.js runtime on a wide variety of platforms, including OS X, Microsoft Windows, Linux, FreeBSD, NonStop,[3] IBM AIX, IBM System z and IBM i. Its work is hosted and supported by the Node.js Foundation,[4] a collaborative project at the Linux Foundation.[5]

Node.js provides an event-driven architecture and a non-blocking I/O API designed to optimize an application's throughput and scalability for real-time web applications. It uses 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 stand-alone web server.

Node.js is used by IBM,[6] Microsoft,[7][8] Yahoo!,[9] Walmart,[10] Groupon,[11] SAP,[12] LinkedIn,[13][14] Rakuten, PayPal,[15][16] Voxer,[17] GoDaddy.,[18] and Netflix.[19]

History

Ryan Dahl, creator of Node.js

Node.js was invented in 2009 by Ryan Dahl and other developers working at Joyent.[20] Node.js was first released in 2009 supporting only Linux. Its development and maintenance was led by Dahl and sponsored by Joyent, the firm where Dahl worked.[21]

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.[22]

The project was demonstrated at the inaugural European JSConf on November 8, 2009.[23][24][25] Dahl presented Node.js, which combined Google's V8 JavaScript engine, an event loop and a low-level I/O API.[20] The project received a standing ovation.[26]

In 2011, a package manager was introduced for the Node.js environment called npm. The package manager makes it easier for the community to publish and share open-source Node.js libraries and is designed to simplify installation, updating and uninstallation of libraries.[20]

In June 2011, Microsoft and Joyent implemented a native Windows version of Node.js.[27] The first Node.js build supporting Windows was released in July 2011.

In January 2012, Dahl stepped aside, promoting coworker and npm creator Isaac Schlueter to manage the project.[28] In January 2014, Schlueter announced Timothy J. Fontaine would be the new project lead.[29]

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.[30]

In February 2015, the intent to form a neutral Node.js Foundation was announced. By June 2015, the Node.js and io.js communities voted to work together under the Node.js Foundation.[31]

Overview

Node.js allows the creation of web servers and networking tools using JavaScript and a collection of "modules" that handle various core functionality.[20][23][32][33][34] Modules handle file system I/O, networking (HTTP, TCP, UDP, DNS, or TLS/SSL), binary data (buffers), cryptography functions, data streams[35] and other core functions.[20][33][36] Node's modules use an API designed to reduce the complexity of writing server applications.[20][33]

Frameworks can be used to accelerate the development of applications, and common frameworks are Express.js, Socket.IO and Connect.[20][37] Node.js applications can run on Microsoft Windows, Unix, NonStop[3] and Mac OS X servers. Node.js applications can alternatively be written with CoffeeScript[38] (an alternative form of JavaScript), Dart or Microsoft TypeScript (strongly typed forms of JavaScript), or any other language that can compile to JavaScript.[38]

Node.js is primarily used to build network programs such as web servers, making it similar to PHP.[32] The biggest difference between PHP and Node.js is that most functions in PHP block until completion, while functions in Node.js are designed to post long lasting tasks to the underlying thread pool and then return to the caller in a non-blocking fashion. A registered callback is then called from the event loop to signal completion of the posted task. This allows enqueuing parallel tasks without explicit threading.[32]

Execution of parallel tasks in Node.js is handled by a thread pool. The main thread call functions that post tasks to the shared task queue which threads in the thread pool pull and execute. Inherently non-blocking system functions like networking translates to kernel side non-blocking sockets, while inherently blocking system functions like file I/O run in a blocking way on its own thread. When a thread in the thread pool completes a task it informs the main thread of this, which in turn wakes up and execute the registered callback. Since callbacks are handled in serial on the main thread, long lasting computations and other CPU-bound tasks will freeze the entire event-loop until completion.

Thousands of open-source libraries have been built for Node.js, most of which are hosted on the npm website. Its developer community has two main mailing lists and the IRC channel #node.js on freenode. There is an annual Node.js developer conference, NodeConf.[39]

Technical

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.[40] The design of sharing a single thread between all the requests is intended for building highly concurrent applications, where any function performing I/O must use a callback. In order to accommodate the single-threaded event loop, Node.js utilizes the libuv library which in turn uses a fixed-sized threadpool that is responsible for all non-blocking asynchronous I/O operations.

A downside of this single-threaded approach is that Node.js doesn't allow horizontal scaling by increasing the number of CPU cores of the machine it is running on without using an additional module, such as cluster,[41] StrongLoop Process Manager[42] or pm2.[43] However, developers can increase the default number of threads in the libuv threadpool; these threads are likely to be distributed across multiple cores by the server operating system.[44]

V8

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

Node.js uses libuv to handle asynchronous events. Libuv is an abstraction layer for network and file system functionality on both Windows and POSIX-based systems like Linux, Mac OS X, OSS on NonStop 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, organizing the installation and management of third-party Node.js programs. 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.[45]

Unified API

Node.js can be combined with a browser, a document database (such as MongoDB or CouchDB) and JSON for a unified JavaScript development stack. With 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, and 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 uses an event loop for scalability, instead of processes or threads.[46] 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
  • ruxit (cloud service, commercial) – SaaS based APM solution[49]
  • AppNeta (cloud service, commercial) – APM for Node.js and distributed environments.[50]
Frameworks
  • Server frameworks – Express.js, Socket.IO, Koa.js, Hapi.js, Total.js, Nodal[51][52][53]
  • MVC frameworks – Meteor, Derby, Sails, Mean, MeanJS, Tower.js, Nombo, Geddy, Compound, Yahoo! Mojito
Social networks
  • Node.js World – a social networking website for Node.js developers

Alternatives

io.js

io.js
io.js logo
Original author(s) Fedor Indutny
Developer(s) io.js Developers, GitHub Contributors
Initial release January 14, 2015 (2015-01-14)[54]
Stable release 3.0.0 / August 4, 2015 (2015-08-04)[55]
Development status Inactive
Written in C, C++, JavaScript
Operating system OS X, Linux, Microsoft Windows
Type Event-driven networking
License MIT
Website iojs.org

io.js was a fork of Node.js started in December 2014[30] by a contributor to the Node.js project.[56] It was expected to be marked stable in March 2015.[57] The reason given for forking Node.js was the authors' concern about working on a project under corporate governance; they created an "open governance" system for io.js, run by a technical steering committee.[56]

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,[58] the authors plan to keep io.js up-to-date with latest releases of V8.[57]

On May 15, 2015, the io.js organization voted to officially merge back with the Node.js project under the governance of a new foundation called the Node Foundation.[59] The organization is named 'nodejs' on GitHub.

JXcore

JXcore is a fork of Node.js targeting mobile devices and IoTs. Its first beta was released in January 2014. It was open sourced[60] on February 13, 2015 and made available through a GitHub repository.[61] JXcore can use either of the Google V8 or Mozilla SpiderMonkey JavaScript engines. As a result, JXcore can run Node applications on iOS devices using SpiderMonkey.

Other languages

Node.js environments available for other programming languages include:

  • Luvit implements the Node.js APIs for the language Lua[62]
  • Node-julia allows using Julia with Node.js/io.js
  • The COBOL bridge for Node.js allows using COBOL with Node.js[63]

See also

Portal icon Free software portal

References

  1. ^ "node-v0.x-archive on Github". Retrieved 2 August 2014. 
  2. ^ "Node.js Previous Releases". Retrieved 13 January 2016. 
  3. ^ a b "bomBora - Node.js for NonStop". Infrasoft. Retrieved 14 August 2015. 
  4. ^ "Node.js Foundation - Node.js". Retrieved 4 July 2015. 
  5. ^ "Linux Foundation Collaborative Projects". Retrieved 4 July 2015. 
  6. ^ "IBM Bluemix". Retrieved 4 July 2015. 
  7. ^ Baxter-Reynolds, Matthew (November 9, 2011). "Here's why you should be happy that Microsoft is embracing Node.js". London: The Guardian. Retrieved May 10, 2012. 
  8. ^ "WebMatrix - Front End Web Developers take note (ASP.NET, PHP, node.js and more)". Retrieved 2 August 2014. 
  9. ^ "Yahoo! Announces Cocktails Shaken, Not Stirred". Retrieved 7 April 2015. 
  10. ^ "Why Walmart is using Node.js". VentureBeat. January 24, 2012. Retrieved May 10, 2012. 
  11. ^ Geitgey, Adam (30 October 2013). "I-Tier: Dismantling the Monoliths". Groupon. Retrieved 30 April 2014. 
  12. ^ "SAP AppBuilder". SAP. March 10, 2014. Retrieved March 10, 2014. 
  13. ^ "You'll never believe how LinkedIn built its new iPad app". VentureBeat. May 2, 2012. Retrieved May 10, 2012. 
  14. ^ "Blazing fast node.js: 10 performance tips from LinkedIn Mobile". Retrieved 7 April 2015. 
  15. ^ "Clash of the Titans: Releasing the Kraken, NodeJS @paypal". fluentconf.com. May 28, 2013. Retrieved September 11, 2013. 
  16. ^ "All such companies and their products in which Node.js is used". Retrieved 2 August 2014. 
  17. ^ The Node Ahead: JavaScript leaps from browser into future, The Register, March 1, 2011
  18. ^ Why GoDaddy’s Nodejitsu deal is great for Node.js, VentureBeat, February 10, 2015
  19. ^ Node.js in Flames November 19, 2014
  20. ^ a b c d e f g Professional Node.js: Building JavaScript Based Scalable Software, John Wiley & Sons, 01-Oct-2012
  21. ^ Alex Handy (2011-06-24). "Node.js pushes JavaScript to the server-side". SDTimes. Retrieved 2011-09-04. 
  22. ^ 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. 
  23. ^ a b Sams Teach Yourself Node.js in 24 Hours, Sams Publishing, 05-Sep-2012
  24. ^ "Ryan Dahl at JSConf EU 2009". 
  25. ^ "Ryan Dahl at JSConf EU 2009 Video". 
  26. ^ http://www.jsconf.eu/2009/video_nodejs_by_ryan_dahl.html
  27. ^ "Porting Node to Windows". Retrieved 2 August 2014. 
  28. ^ Dahl, Ryan. "New gatekeeper". Retrieved 26 October 2013. 
  29. ^ Schlueter, Isaac (January 15, 2014). "The Next Phase of Node.js". Retrieved 21 January 2014. 
  30. ^ a b Krill, Paul (Dec 4, 2014). "Why io.js Decided to Fork Node.js". JavaWorld. Retrieved Dec 15, 2014. 
  31. ^ "Node.js Foundation Advances Community Collaboration, Announces New Members and Ratified Technical Governance". Retrieved 4 July 2015. 
  32. ^ a b c Node.js for PHP Developers, O'Reilly Media, Inc., 2013
  33. ^ a b c Node.js Essentials, Packt Publishing, 09-Sep-2014
  34. ^ Smashing Node.js: JavaScript Everywhere, John Wiley & Sons, 14-Aug-2012
  35. ^ Streams in node.js : Readable and Writable
  36. ^ Modules, Nodejs Website
  37. ^ Express.js Guide: The Comprehensive Book on Express.js, Azat Mardan, 28-May-2014
  38. ^ a b "CoffeeScript on Node.js". O'Reilly Media, Inc. April 15, 2013. Retrieved May 17, 2015. 
  39. ^ Finley, Klint (April 7, 2011). "NodeConf Schedule Announced". ReadWriteHack. Retrieved 2 August 2014. 
  40. ^ http://blog.caustik.com/2012/08/19/node-js-w1m-concurrent-connections/
  41. ^ cluster
  42. ^ StrongLoop Process Manager
  43. ^ pm2
  44. ^ http://www.future-processing.pl/blog/on-problems-with-threads-in-node-js/
  45. ^ Grunt
  46. ^ About Node.js, Node.js Website
  47. ^ "Node.js Tools for Visual Studio". Codeplex. Retrieved 2 August 2014. 
  48. ^ "Bergius: Flowhub and the GNOME Developer Experience". LWN.net. 2014-05-02. Retrieved 2014-05-24. 
  49. ^ Mike Kopp (2014-11-27). "There’s a new kid in town: node.js monitoring". blog.ruxit.com. Retrieved 2014-11-28. 
  50. ^ Dan Kuebrich (2014-09-10). "Introducing TraceView for Node.js Applications". appneta.com/blog. Retrieved 2014-09-11. 
  51. ^ Node.js Framework Comparison: Express vs. Koa vs. Hapi, AirPair
  52. ^ Peter Wayner (21 May 2014). "13 fabulous frameworks for Node.js". InfoWorld. Retrieved 4 July 2015. 
  53. ^ "Nodal: An ES6 API Server". 
  54. ^ "Release v1.0.0-release". Retrieved 2 February 2015. 
  55. ^ "Release v3.0.0". Retrieved 12 August 2015. 
  56. ^ a b Q&A: Why io.js decided to fork Node.js, Infoworld Tech Watch
  57. ^ a b Mikeal, Rogers (January 28, 2015). "State of io.js". Retrieved 2 February 2015. 
  58. ^ Ben Noordhuis (Nov 12, 2014). "Issue 3692: function suddenly becomes undefined". V8 JavaScript Engine Issues. Retrieved 2 February 2015. 
  59. ^ "io.js and Node.js merge". Retrieved 27 June 2015. 
  60. ^ Serdar Yegulalp (20 February 2015). "Node.js fork JXcore goes open source, aims for mobile developers". InfoWorld. Retrieved 4 July 2015. 
  61. ^ https://github.com/jxcore/jxcore
  62. ^ Luvit
  63. ^ [1] COBOL bridge for Node.js

Further reading

External links

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fonte: https://web.archive.org/web/20160121074828/https://en.wikipedia.org/wiki/Node.js