More Information About webkit

WebKit
Developed by	Apple Inc., Trolltech, Nokia, Adobe, Google, others.
OS	Cross-platform
Type	Application framework
License	LGPLv2/BSD-style
Website	http://webkit.org

WebKit is an open source application framework that provides a foundation upon which to build a web browser. WebKit was originally derived from the Konqueror browser’s KHTML software library by Apple, Inc. for use as the engine of Mac OS X’s Safari web browser, and has now been further developed by Apple, Nokia, Google and others. The framework is now used by Omniweb, Shiira, iCab, Adobe AIR, Google Chrome, mobile phones (including the iPhone), Nokia’s Series 60 browser and Google’s Android platform. Although WebKit is included with Trolltech’s Qt 4.4, the underlying framework for KDE,^[1] the KDE project will use its original version of KHTML for the near future.^[2]

It passes the Acid2 test, and as of March 2008, latest nightly builds of WebKit score 100/100^[3] in the Acid3 test with pixel-perfect rendering and no timing or smoothness issues (at least as of revision 35249).

History

WebKit began when Apple Inc. created a software fork of the KDE project’s HTML layout engine KHTML and KDE's JavaScript engine (KJS). Apple developers explained in an email to KDE developers^[4] that these engines allowed easier development than other technologies by nature of being small (less than 140,000 lines of code), cleanly designed and standards compliant. KHTML and KJS were ported to Mac OS X with the help of an adapter library and renamed WebCore and JavaScriptCore.^[4] JavaScriptCore was first included with Mac OS X v10.2 as a private framework which Apple used within their Sherlock application, while WebCore debuted with the first beta of Safari. Mac OS X v10.3 was the first major release of Apple's operating system to bundle WebKit, although it had already been bundled with a minor release of 10.2.

JavaScriptCore was announced in an email to a KDE mailing list in June 2002, alongside the first release of Apple's changes.^[5] WebCore was announced at the Macworld Expo in January 2003 by Apple CEO Steve Jobs with the release of the Safari web browser.^[6] In time, Apple’s cooperation with KDE was criticized, with changes being mostly submitted in bulk back to the KDE project. While this helped Konqueror pass the Acid2 test, the source code had already diverged so much that improvements were difficult to share back and forth.^[7]

On June 7, 2005, Safari developer Dave Hyatt announced on his weblog that Apple was open sourcing WebKit (previously, only WebCore and JavaScriptCore were open source) and opening up access to WebKit’s CVS tree and Bugzilla tool.^[8] This was announced at Apple’s Worldwide Developers Conference 2005 by Bertrand Serlet. The next week, Nokia announced that it was developing a browser based on WebKit, which was later named Web Browser for S60.

In mid-December 2005 support for Scalable Vector Graphics was merged into the standard build^[9] and in early January 2006 the source code was migrated from CVS to Subversion. In June 2007, a Microsoft Windows port was added to WebKit. The next month the Ars Technica website published an article announcing that the KDE team would move from KHTML to WebKit.^[10]

Components

WebCore

WebCore is a layout, rendering, and Document Object Model (DOM) library for HTML and SVG, developed by the WebKit project. Its complete source code is licensed under the LGPL. The WebKit framework wraps WebCore and JavaScriptCore, providing an Objective-C application programming interface to the C++-based WebCore rendering engine and JavaScriptCore script engine, allowing it to easily be referenced by applications based on the Cocoa API; later versions also include a cross-platform C++ platform abstraction, and various ports provide additional APIs.

JavaScriptCore

JavaScriptCore is a framework that provides a JavaScript engine for WebKit implementations, and provides this type of scripting in other contexts within Mac OS X.^[11][12] JavaScriptCore is originally derived from KDE’s JavaScript engine (KJS) library (which is part of the KDE project) and the PCRE regular expression library. Since forking from KJS and PCRE, JavaScriptCore has been improved with many new features and greatly improved performance.^[13]

JavaScriptCore is currently being rewritten by the WebKit project as SquirrelFish to turn it into a bytecode interpreter^[14].

Drosera

Drosera is a JavaScript debugger that was included with the nightly builds of WebKit.^[15][16] It was named after Drosera, a genus of carnivorous plants (i.e. bug-eaters). Drosera has been replaced by the inclusion of debugging functionality in the Web Inspector.^[17]

Ports

WebKit, being a portable and popular open source project, has attracted ports to several operating systems and toolkits. It is used in the Nokia Series 60 browser,^[18] while the community^[19] is porting the browser engine to the GTK+ toolkit and a port to the Qt toolkit is being developed by community and several companies including Trolltech. Trolltech includes the Qt port in the Qt 4.4 release. The Qt port of WebKit will also be available to be used in Konqueror in KDE 4.1.^[10]

There are also ongoing ports for the open source operating systems Syllable,^[20] Haiku^[21] and AROS.^[22]

Apple has ported WebKit to the iPhone, where it is used to render content within the phone’s web browser and email software.^[23] Adobe Systems uses WebKit in the Adobe Integrated Runtime, and the upcoming Android mobile phone platform will use WebKit as the basis of its web browser.^[24]

There is also a project synchronized with WebKit (sponsored by Pleyo)^[25] called Origyn Web Browser, which provides a meta-port to an abstract platform that makes porting to embedded or lightweight systems quicker and easier.^[26] This port is used for embedded devices such as set-top boxes, PMP and also the AmigaOS official port.^[27]

The development team of GNOME's web browser, Epiphany, announced in April 2008^[28] that it will use WebKit exclusively, and stop supporting the Mozilla Foundation's Gecko layout engine. Epiphany supported both Gecko and WebKit for some time, but the team decided that Gecko's release cycle and future development plans would make it cumbersome to continue supporting it.

Using the Qt port is a browser named Arora.^[29] Arora is a very basic browser which includes features like "History" and "Bookmarks". It does not yet support Netscape plugins, but support is planned to arive in Qt 4.5. It works on Linux, OS X, Windows, and embedded Linux using Qt Embedded.

Google has released a beta of an open-source browser called Google Chrome, based on WebKit. ^{[30] [31]}

See also

• Comparison of layout engines
• List of KHTML and WebKit-based browsers
• List of graphical layout engines

References

External links

• The WebKit Open Source Project – Official site
• Webkit Qt – Official site of the Trolltech’s Qt port of WebKit
• Apple’s Safari and WebKit version history matrix