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Tamarin (JavaScript engine)

Tamarin (JavaScript engine)

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Tamarin is a free
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 virtual machine
Virtual machine
A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". Modern virtual machines are implemented with either software emulation or hardware virtualization or both together.-VM Definitions:A virtual machine is a software...

 with just-in-time compilation
Just-in-time compilation
In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...

 (JIT) support intended to implement the fourth edition of the ECMAScript
ECMAScript is the scripting language standardized by Ecma International in the ECMA-262 specification and ISO/IEC 16262. The language is widely used for client-side scripting on the web, in the form of several well-known dialects such as JavaScript, JScript, and ActionScript.- History :JavaScript...


Tamarin was developed by Adobe Labs
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...

 for its ActionScript
ActionScript is an object-oriented language originally developed by Macromedia Inc. . It is a dialect of ECMAScript , and is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on Web pages in the form of...

 virtual machine used in Flash 9
Adobe Flash
Adobe Flash is a multimedia platform used to add animation, video, and interactivity to web pages. Flash is frequently used for advertisements, games and flash animations for broadcast...

 and up and open-sourced in 2006.

Tamarin and Mozilla

The code was donated to the Mozilla
Mozilla is a term used in a number of ways in relation to the Mozilla.org project and the Mozilla Foundation, their defunct commercial predecessor Netscape Communications Corporation, and their related application software....

 project on November 7, 2006. The contributed code is tri-licensed under the GPL
GNU General Public License
The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....

GNU Lesser General Public License
The GNU Lesser General Public License or LGPL is a free software license published by the Free Software Foundation . It was designed as a compromise between the strong-copyleft GNU General Public License or GPL and permissive licenses such as the BSD licenses and the MIT License...

, and MPL
Mozilla Public License
The Mozilla Public License is a free and open source software license. Version 1.0 was developed by Mitchell Baker when she worked as a lawyer at Netscape Communications Corporation and version 1.1 at the Mozilla Foundation...

 licenses to be developed in Mozilla's Mercurial
Mercurial (software)
Mercurial is a cross-platform, distributed revision control tool for software developers. It is mainly implemented using the Python programming language, but includes a binary diff implementation written in C. It is supported on Windows and Unix-like systems, such as FreeBSD, Mac OS X and Linux...

 repository. The contributed code is approximately 135,000 lines of code, making it the largest single donation of code to the Mozilla project besides Netscape
Netscape (web browser)
Netscape 7 was a series of proprietary cross-platform Internet suites created by Netscape Communications Corporation and then in-house by AOL to continue the Netscape series after Netscape 6. There were three main editions released from the Netscape 7 series; being Netscape 7.0, 7.1 and 7.2...


There were plans to use Tamarin as part of Mozilla
Mozilla application framework
The Mozilla application framework is a collection of cross-platform software components that make up the Mozilla applications. It was originally known as XPFE, an abbreviation of cross-platform front end. It was also known as XPToolkit...

 2 (and therefore Firefox
Mozilla Firefox
Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...

). The project to integrate Tamarin and SpiderMonkey was called "ActionMonkey", but was canceled in 2008 because Tamarin's interpreter turned out to be slower than SpiderMonkey's and because the plans of ECMAScript development shifted from ECMAScript 4 (which was partially implemented by Tamarin) to ECMAScript Harmony.

Tamarin continues to be used in Adobe Flash Player
Adobe Flash Player
The Adobe Flash Player is software for viewing multimedia, Rich Internet Applications and streaming video and audio, on a computer web browser or on supported mobile devices. Flash Player runs SWF files that can be created by the Adobe Flash authoring tool, by Adobe Flex or by a number of other...

, but it has not replaced SpiderMonkey as the JavaScript engine
JavaScript engine
A JavaScript engine is specialized computer software which interprets and executes JavaScript . Although there are several uses for a JavaScript engine, it is most commonly used in web browsers.-History:...

 of Mozilla applications.

The only part of Tamarin used in modern Mozilla applications (e.g. Firefox 3.5+) via SpiderMonkey is NanoJIT, a module that's used to generate native code when performing just-in-time compilation
Just-in-time compilation
In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...


What Tamarin is not

Adobe contributed code for its virtual machine and the JIT
Just-in-time compilation
In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...

 compiler. The JavaScript compiler (the program generating bytecode
Bytecode, also known as p-code , is a term which has been used to denote various forms of instruction sets designed for efficient execution by a software interpreter as well as being suitable for further compilation into machine code...

 from JavaScript source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...

) was not contributed as part of Tamarin.

Tamarin is not the same as Adobe's Flash Player, which remains closed source. The virtual machine is only a part of Flash Player.

Related projects

Two projects related to Tamarin were announced on July 25, 2007 in Brendan Eich
Brendan Eich
Brendan Eich is a computer programmer and creator of the JavaScript scripting language. He is the chief technology officer at the Mozilla Corporation.-Education:...

's keynote at The Ajax Experience West: IronMonkey and ScreamingMonkey. IronMonkey is a project to map IronPython
IronPython is an implementation of the Python programming language targeting the .NET Framework and Mono. Jim Hugunin created the project and actively contributed to it up until Version 1.0 which was released on September 5, 2006. Thereafter, it was maintained by a small team at Microsoft until...

 and IronRuby
IronRuby is an implementation of the Ruby programming language targeting Microsoft .NET framework. It is implemented on top of the Dynamic Language Runtime , a library running on top of the Common Language Infrastructure that provides dynamic typing and dynamic method dispatch, among other things,...

 to Tamarin led by Seo Sanghyeon. ScreamingMonkey's goal is to allow Tamarin to run within non-Mozilla browsers (thus allowing them to understand JavaScript 2), starting with Internet Explorer
Internet Explorer
Windows Internet Explorer is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year...

. The project is led by Mark Hammond. Neither project had production-quality releases and their current status is unclear.


Both SpiderMonkey and Tamarin fulfill closely related goals and so were both dubbed after monkeys (the spider monkey
Spider monkey
Spider monkeys of the genus Ateles are New World monkeys in the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil...

 and the tamarin
The tamarins are squirrel-sized New World monkeys from the family Callitrichidae in the genus Saguinus. They are closely related to the lion tamarins in the genus Leontopithecus.- Range :...

, respectively).

Further reading

External links