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Node.js
Original author(s)Ryan Dahl
Developer(s)Node.js Developers, Joyent, GitHub Contributors
Initial releaseMay 27, 2009 (2009-05-27)[1]
Stable release
5.5.0 / January 20, 2016 (2016-01-20)[2]
Repository
Written inC, C++, JavaScript
Operating systemOS X, Linux, Solaris, FreeBSD, OpenBSD, Microsoft Windows (older versions require Cygwin), webOS, NonStop OS
TypeEvent-driven networking
LicenseMIT
Websitenodejs.org

Node.js is an open-source, cross-platform runtime environment for developing server-side Web applications. Node.js is not a JavaScript framework,[3] but its applications are written in JavaScript and can be run within the Node.js runtime on a wide variety of platforms, including FreeBSD, IBM AIX, IBM i, IBM System z, Linux, Microsoft Windows, NonStop and OS X.[4] Its work is hosted and supported by the Node.js Foundation,[5] a collaborative project at the Linux Foundation.[6]

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 GoDaddy,[7] Groupon,[8] IBM,[9] LinkedIn,[10][11] Microsoft,[12][13] Netflix,[14] PayPal,[15][16] Rakuten, SAP,[17] Voxer,[18] Walmart,[19] and Yahoo!.[20]

Node.js is typically used where light-weight, real-time response is needed, like communication apps and Web-based gaming. It is used to build large, scalable network applications.[21]

History

Ryan Dahl, creator of Node.js

Node.js was written in 2009 by Ryan Dahl and other developers working at Joyent, [22] The initial 2009 release supported only Linux. Its development and maintenance was led by Dahl and sponsored by Joyent, the firm where Dahl worked.[23][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.[24][21]

The project was demonstrated at the inaugural European JSConf on November 8, 2009.[25][26][27] Dahl presented Node.js, which combined Google's V8 JavaScript engine, an event loop and a low-level I/O API.[22] The project received a standing ovation.[28]

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.[22]

In June 2011, Microsoft and Joyent implemented a native Windows version of Node.js.[29] 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.[30] In January 2014, Schlueter announced Timothy J. Fontaine would be the new project lead.[31]

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.[32]

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.[33]

Overview

Node.js allows the creation of Web servers and networking tools using JavaScript and a collection of "modules" that handle various core functionality.[22][25][34][35][36] It is a kind of server-side browser.[37] Modules handle file system I/O, networking (DNS, HTTP, TCP, TLS/SSL, or UDP), binary data (buffers), cryptography functions, data streams[38] and other core functions.[22][35][39] Node.js's modules use an API designed to reduce the complexity of writing server applications.[22][35]

Frameworks can be used to accelerate the development of applications, and common frameworks are Connect, Express.js, and Socket.IO.[22][40] Node.js applications can run on Mac OS X, Microsoft Windows, NonStop,[4] and Unix servers. They can alternatively be written with CoffeeScript[41] (a JavaScript alternative), Dart or Microsoft TypeScript (strongly typed forms of JavaScript), or any other language that can compile to JavaScript.[41]

Node.js is primarily used to build network programs such as Web servers, making it similar to PHP.[34] The biggest difference between Node.js and PHP 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.[34]

Execution of parallel tasks in Node.js is handled by a thread pool. The main thread call functions post tasks to the shared task queue that 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 that 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, called NodeConf.[42]

Cons and pros

As every platform on the market, Node.js has some strengths and weaknesses. Here is a list of cons & pros about it. Generally, Node.js does not have a better performance than matured platforms like .NET.[43]

Cons
  • .NET is more versatile and powerful than Node.js.[43]
  • Any CPU-intensive code will block the entire system, making the application unresponsive.[37][43]
  • Ending up always with a callback results in a huge number of nested callbacks.[37]
  • Java has more mature development tools than JavaScript/Node.js.[44]
  • Node.js does not provide scalability.[37]
  • Static Java has Netty and Play is faster.[44]
  • Using relational databasees with Node.js is difficult.[37]
Pros
  • As the V8 engine is written in C, Node.js runs much faster than Perl, Python, or Ruby.[37]
  • Client-side and server-side code can be shared.[37]
  • Easy to make end-to-end development, as both frontend and backend use JavaScript[44]
  • Easy to start with, and having the possibility to do complex things.[43]
  • For non-CPU-intensive applications, Node.js is out-of-the-box faster than other servers.[45]
  • It's possible to stream big files.[37]
  • JavaScript, the language Node.js uses, is actually more succinct in a few small ways with the "feature" of not requiring strict variable types.[44]
  • Node.js can handle thousands of concurrent connections with a minimal overhead.[37]
  • Node.js has an ever-growing large community.[37]
  • Node.js is not designed for CPU-intensive tasks and will perform bad, if the application does execute such.[43]
  • Node.js is not single-threaded; for a time-consuming process, like an I/O-bound operation, the single thread to which the developer has access only delegates the task to a thread in V8 that is in a pool of underlying C++ threads. Although this is a very good, scalable, highly-available way to write code, one can easily create this exact pattern in other platforms, like .NET.[43]
  • Node.js must parse to and from JSON, like .NET must serialize to and from JSON to interact with .NET objects, but parsing is much cheaper in Node.js concerning overhead than serializing in .NET.[43]
  • The node packaged module is included and is becomming stronger[37]
  • Uses easy-to-learn JavaScript as language.[37][43]
  • Using JavaScript on both on the client- and server-side a reduces the impedance mismatch between the two programming environments that can communicate data structures via JSON. Duplicate form validation code can be shared between server and client, etc.[37]
  • Using just simple JavaScript, Node.js is not something new for programmers, so JavaScript developers don’t have to put much extra effort to learn Node.js.[37]

Technical features

At it's core, Node.js is a “proto-server” that processes incoming requests in a loop, called the event loop, and does nothing out-of-the-box.[3]

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.[46] 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 that in turn uses a fixed-sized threadpool that is responsible for all non-blocking asynchronous I/O operations.[21]

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,[47] StrongLoop Process Manager[48] or pm2.[49] 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.[50]

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.[21]

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.[51]

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.[52] 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
  • AppNeta (cloud service, commercial) – APM for Node.js and distributed environments.[55]
  • ruxit (cloud service, commercial) – SaaS based APM solution[56]
Frameworks
  • MVC frameworks – Meteor, Derby, Sails, Mean, MeanJS, Tower.js, Nombo, Geddy, Compound, Yahoo! Mojito
  • Server frameworks – Express.js, Socket.IO, Koa.js, Hapi.js, Total.js, Nodal[57][58][59]
Social networks
  • Node.js World – a social networking website for Node.js developers

Alternatives

io.js

io.js
Original author(s)Fedor Indutny
Developer(s)io.js Developers, GitHub Contributors
Initial releaseJanuary 14, 2015 (2015-01-14)[60]
Stable release
3.0.0 / August 4, 2015 (2015-08-04)[61]
Repository
Written inC, C++, JavaScript
Operating systemOS X, Linux, Microsoft Windows
TypeEvent-driven networking
LicenseMIT
Websiteiojs.org
Wikimedia Commons has media related to io.js.

io.js was a fork of Node.js started in December 2014[32] by a contributor to the Node.js project.[62] It was expected to be marked stable in March 2015.[63] 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.[62]

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 Linux, Microsoft Windows, and OS X. 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,[64] the authors plan to keep io.js up-to-date with latest releases of V8.[63]

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.[65] 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[66] on February 13, 2015 and made available through a GitHub repository.[67] 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[68]
  • Node-julia allows using Julia with Node.js/io.js
  • The COBOL bridge for Node.js allows using COBOL with Node.js[69]

References

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  2. ^ "Node.js Previous Releases". Retrieved 20 January 2016.
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  5. ^ "Node.js Foundation - Node.js". Retrieved 4 July 2015.
  6. ^ "Linux Foundation Collaborative Projects". Retrieved 4 July 2015.
  7. ^ Why GoDaddy’s Nodejitsu deal is great for Node.js, VentureBeat, February 10, 2015
  8. ^ Geitgey, Adam (30 October 2013). "I-Tier: Dismantling the Monoliths". Groupon. Retrieved 30 April 2014.
  9. ^ "IBM Bluemix". Retrieved 4 July 2015.
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  11. ^ "Blazing fast node.js: 10 performance tips from LinkedIn Mobile". Retrieved 7 April 2015.
  12. ^ 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.
  13. ^ "WebMatrix - Front End Web Developers take note (ASP.NET, PHP, node.js and more)". Retrieved 2 August 2014.
  14. ^ Node.js in Flames November 19, 2014
  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. ^ "SAP AppBuilder". SAP. March 10, 2014. Retrieved March 10, 2014.
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  28. ^ http://www.jsconf.eu/2009/video_nodejs_by_ryan_dahl.html
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  32. ^ a b Krill, Paul (Dec 4, 2014). "Why io.js Decided to Fork Node.js". JavaWorld. Retrieved Dec 15, 2014.
  33. ^ "Node.js Foundation Advances Community Collaboration, Announces New Members and Ratified Technical Governance". Retrieved 4 July 2015.
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  38. ^ Streams in node.js: Readable and Writable
  39. ^ Modules, Nodejs Website
  40. ^ Express.js Guide: The Comprehensive Book on Express.js, Azat Mardan, 28-May-2014
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  42. ^ Finley, Klint (April 7, 2011). "NodeConf Schedule Announced". ReadWriteHack. Retrieved 2 August 2014.
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  46. ^ Node.js w/1M concurrent connections!
  47. ^ Node.js v5.5.0 Documentation
  48. ^ StrongLoop Process Manager
  49. ^ Production process manager for Node.js applications with a built-in load balancer http://pm2.keymetrics.io/
  50. ^ On problems with threads in node.js
  51. ^ GRUNT: The JavaScript Task Runner
  52. ^ About Node.js, Node.js Website
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  55. ^ Dan Kuebrich (2014-09-10). "Introducing TraceView for Node.js Applications". appneta.com/blog. Retrieved 2014-09-11.
  56. ^ Mike Kopp (2014-11-27). "There's a new kid in town: node.js monitoring". blog.ruxit.com. Retrieved 2014-11-28.
  57. ^ Node.js Framework Comparison: Express vs. Koa vs. Hapi, AirPair
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  59. ^ "Nodal: An ES6 API Server".
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  61. ^ "Release v3.0.0". Retrieved 12 August 2015.
  62. ^ a b Q&A: Why io.js decided to fork Node.js, Infoworld Tech Watch
  63. ^ a b Mikeal, Rogers (January 28, 2015). "State of io.js". Retrieved 2 February 2015.
  64. ^ Ben Noordhuis (Nov 12, 2014). "Issue 3692: function suddenly becomes undefined". V8 JavaScript Engine Issues. Retrieved 2 February 2015.
  65. ^ "io.js and Node.js merge". Retrieved 27 June 2015.
  66. ^ Serdar Yegulalp (20 February 2015). "Node.js fork JXcore goes open source, aims for mobile developers". InfoWorld. Retrieved 4 July 2015.
  67. ^ Evented IO for Chakra, SpiderMonkey & V8 JavaScript http://jxcore.com
  68. ^ Luvit
  69. ^ COBOL bridge for Node.js

Further reading

See also

Wikimedia Commons has media related to Node.js.
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