KDE

K Desktop Environment

Screenshot of KDE 4.1.2 showing Kickoff and the folderview
Developed by	The KDE Team
Initial release	1998
Written in	C++ and Qt
Platform	Cross-platform (Linux, BSD, Solaris, Windows, Mac OS X)
Available in	Multilingual (more than 80 different languages)
Development status	active
Type	Desktop environment
License	GNU General Public License and others[1]
Website	http://www.kde.org/

KDE (K Desktop Environment) (IPA: /ˌkeɪdiːˈiː/) is a Free software project based around its flagship product - a desktop environment for Unix-like systems. The goal of the project is to provide basic desktop functions and applications for daily needs as well as tools and documentation for developers to write stand-alone applications for the system. In this regard, the KDE project serves as an umbrella project for many standalone applications and smaller projects that are based on KDE technology. These include KOffice, KDevelop, Amarok, K3b and many others. KDE software is based on the Qt toolkit. The licensing of this toolkit largely restricted KDE software to free operating systems, but with the release of Qt 4 these restrictions have eased. This allows KDE software based on Qt 4 to be distributed on Windows and Mac OS X. Ports of KDE software to these platforms are underway.

History

See also: History of free software#Desktop

Origins

KDE was founded in 1996 by Matthias Ettrich, who was then a student at the Eberhard Karls University of Tübingen. At the time, he was troubled by certain aspects of the Unix desktop. Among his qualms was that none of the applications looked, felt, or worked alike. He proposed the formation of not only a set of applications, but rather a desktop environment, in which users could expect things to look, feel, and work consistently. He also wanted to make this desktop easy to use; one of his complaints with desktop applications of the time was that his girlfriend could not use them. His initial Usenet post spurred a lot of interest, and the KDE project was born.^[2]

The name KDE was intended as a word play on the existing Common Desktop Environment, available for Unix systems. CDE was an X11-based user environment jointly developed by HP, IBM, and Sun, through the X/Open Company, with an interface and productivity tools based on the Motif graphical widget toolkit. It was supposed to be an intuitively easy-to-use desktop computer environment.^[3] The K was originally suggested to stand for "Kool", but it was quickly decided that the K should stand for nothing in particular. Additionally, one of the tips in certain versions of KDE 3 incorrectly states that the K currently is just meant to be the letter before L in the Latin alphabet, the first letter in the word Linux (which is where KDE is usually run).^[4]

Matthias Ettrich chose to use the Qt toolkit for the KDE project. Other programmers quickly started developing KDE/Qt applications, and by early 1997, a few applications were being released.

First series

KDE 1.0

On 12 July 1998 KDE 1.0 was released. In the release announcement the KDE team outlined the project and its reasons for creation:

KDE is a network transparent, contemporary desktop environment for UNIX workstations. KDE seeks to fill the need for an easy to use desktop for Unix workstations, similar to the desktop environments found under the MacOS or Window95/NT. We believe that the UNIX operating system is the best operating system available today. In fact UNIX has been the undisputed choice of the information technology professional for many years. When it comes to stability, scalability and openness there is no competition to UNIX. However, the lack of an easy to use contemporary desktop environment for UNIX has prevented UNIX from finding its way onto the desktops of the typical computer user in offices and homes.

With KDE there is now an easy to use, contemporary desktop environment available for UNIX. Together with a free implementation of UNIX such as Linux, UNIX/KDE constitutes a completely free and open computing platform available to anyone free of charge including its source code for anyone to modify. While there will always be room for improvement we believe to have delivered a viable alternative to some of the more commonly found and commercial operating systems/desktops combinations available today. It is our hope that the combination UNIX/KDE will finally bring open, reliable, stable and monopoly free computing to the average computer.

—KDE 1.0 Release Announcement^[5]

In November 1998, the Qt toolkit was dual-licensed under the free/open source Q Public License (QPL) & a commercial-license for proprietary software developers. The same year, the KDE Free Qt foundation^[6] was created which guarantees that Qt would fall under a variant of the very liberal BSD license should Trolltech cease to exist or no free/open source version of Qt be released during 12 months. Debate continued about compatibility with the GNU General Public License (GPL), so in September 2000, Trolltech made the Unix version of the Qt libraries available under the GPL, in addition to the QPL, which eliminated the concerns of the Free Software Foundation.

Second and third series

KDE 2.0

The second series of releases, KDE 2, introduced significant technological improvements.^[7] These included DCOP (Desktop COmmunication Protocol), KIO, an application I/O library. KParts, a component object model, allowing an application to embed another within itself, and KHTML, an HTML rendering and drawing engine.^[7]

KDE 3.2 with Konqueror and the About screen. This has been described as a watershed release. ^[8]

The third series was much larger than the previous series, consisting of six major releases. The API changes between KDE 2 and KDE 3 were comparatively minor, meaning that the KDE 3 can be seen as largely a continuation of the KDE 2 series. All releases of KDE 3 were built upon Qt 3, which was only released under the GPL for Linux and Unix-like operating systems, including Mac OS X. For that reason, KDE 3 was only available on Windows through ports involving an X server.

Fourth series

KDE 4.0 with Dolphin and System Settings

KDE 4 is based on Qt 4 which is also released under the GPL for Windows and Mac OS X. Therefore KDE 4 applications can be compiled and run natively on these operating systems as well.

KDE 4 includes many new technologies and technical changes. The centerpiece is a redesigned desktop and panels collectively called Plasma which replaces Kicker, KDesktop, and SuperKaramba by integrating their functionality into one piece of technology, and is intended to be more configurable for those wanting to update the decades-old desktop metaphor. There are a number of new frameworks, including Phonon, a new multimedia interface making KDE independent of any one specific media backend, Solid, an API for network and portable devices, and Decibel, a new communication framework to integrate all communication protocols into the desktop. Also featured is a metadata and search framework, incorporating Strigi as a full-text file indexing service, and NEPOMUK with KDE integration.^[9]

The release of KDE 4.0 was met with a mixed reception. While early adopters were tolerant of the lack of finish for some of its new features, the release was widely criticised because of a lack of stability and its "beta" quality. Many expected it to be an upgrade of KDE 3.5, when in fact features regressed due to its extensive changes - some of which were still works in progress. The criticism has emerged in spite of the environment being labelled as non-final in distributions such as OpenSUSE. On the other hand favourable reviews praised KDE 4.0 for its revolutionary changes.

Organization

Like many free/open source software projects, KDE is primarily a volunteer effort, although various companies, such as Novell (in the form of SuSE), Qt Software, and Mandriva, employ developers to work on the project. Since a large number of individuals contribute to KDE in various ways (e.g. code, translation, artwork), organization of such a project is complex. Most problems are discussed on a number of different mailing lists. Important decisions, such as release dates and inclusion of new applications, are made on the kde-core-devel list by core developers. These are developers who have made significant contributions to KDE over a long period of time. Decisions are not made by a formal voting process, but by discussion on the mailing lists. In most cases this seems to work well, and major debates (such as the question of whether the KDE 2 API should be broken in favour of KDE 3) are rare.

The KDE project and related events are frequently sponsored by individuals, universities, and businesses.^[10] On 15 October 2006, it was announced that Mark Shuttleworth had become the first patron of KDE, the highest level of sponsorship available.^[11] On 2007-07-07, it was announced that Intel Corporation and Novell had also become patrons of KDE.^[12]

While developers and users are now located all over the world, the project retains a strong base in Germany. The web servers are located at the universities of Tübingen and Kaiserslautern, a German non-profit organization (KDE e.V.) owns the trademark on KDE and KDE conferences often take place in Germany.

Identity

Konqi, mascot of the KDE project

Kandalf the wizard

Many KDE applications have a K in the name, mostly as an initial letter and capitalized. However, there are notable exceptions like kynaptic, whose K is not capitalized, and Amarok (formerly named amaroK). The K in many KDE applications is obtained by spelling a word which originally begins with C or Q differently, for example Konsole and Kuickshow. Also, some just prefix a commonly used word with a K, for instance KOffice. This seems to be an increasing trend among KDE 4 applications and technologies. However, some applications do not have a K in the name at all, such as Gwenview.

The KDE project's mascot is a green dragon named Konqi. Kandalf was the former mascot for the KDE project during its 2.x versions. He was subsequently replaced possibly due to copyright infringement issues related to Kandalf's similarity to the wizard Gandalf (from J. R. R. Tolkien's The Lord of the Rings).

Development

KDE is built using the Qt toolkit which runs on most Unix and Unix-like systems, Mac OS X and Microsoft Windows. Both KDE and GNOME now participate in freedesktop.org, an effort to standardize Unix desktop interoperability, although there is still some competition between them.^[13]

Release cycle

The KDE team releases new versions on a regular basis.

Platform releases

Platform releases are major releases that begin a series (version number X.0). These releases are allowed to break both binary and source code compatibility with the predecessor, or to put it differently, all following releases (X.1, X.2, ...) will guarantee source & binary compatibility (API & ABI). This means, for instance, that software that was developed for KDE 3.0 will work on all (future) KDE 3 releases, in contrast to an application that was developed for KDE 2, which is not guaranteed to be able to make use of the KDE 3 libraries. KDE major version numbers follow the Qt release cycle meaning that KDE 4 is based on Qt 4, while KDE 3 was based on Qt 3.

Standard releases

There are two main types of releases, major releases and maintenance releases.

Major releases (with two version numbers, for example 3.5) contain new features. As soon as a major release is ready and announced, work on the next major release starts. A major release needs several months to be finished and many bugs that are fixed during this time are backported to the stable branch, meaning that these fixes are incorporated into the last stable release by maintenance releases. Starting with the KDE 4 series, KDE has a major release roughly every six months.

Maintenance releases have three version numbers, e.g. KDE 1.1.1, and focus on fixing bugs, minor glitches and making small usability improvements. Maintenance releases in general do not allow new features although some releases include small enhancements. A shortened release schedule is used. Starting with the KDE 4 series, KDE has a maintenance release roughly every month, except during the month of a major release.

Applications

The Kontact personal information manager and Konqueror file manager/web browser running on KDE 3.5

Major applications for KDE include:

• Amarok - Audio player
• Dolphin - File manager
• K3b - Optical disc authoring software
• Kate - Text editor
• KDevelop - Integrated development environment
• Konsole - Terminal emulator
• Kontact - Personal information manager featuring an e-mail client, a news client, a feed aggregator, To-do lists and more.
• Kopete - Instant messaging client
• Konqueror - Web browser
• KOffice - Office suite

For more applications, see list of KDE applications.

Base technologies

• KDELibs
• KHTML - HTML engine
• KIO - extensible network-transparent file access
• Kiosk - allows disabling features within KDE to create a more controlled environment
• KParts - lightweight in-process graphical component framework
• KWin - window manager
• XMLGUI - allows defining UI elements such as menus and toolbars via XML files

Technologies added in KDE 4

• Plasma - desktop and panel widget engine
• Phonon - multimedia framework
• Solid - device integration framework
• Sonnet - spell checker
• ThreadWeaver - library to use multiprocessor systems more effectively

Technologies superseded in KDE 4

• aRts - sound server (replaced with Phonon)
• DCOP - inter-process communication system (replaced with D-Bus)

Toolkit licensing

Qt, to which native graphical KDE applications link for their graphical widgets, is free software, dual-licensed under the GNU GPL versions 2 and 3, and QPL licenses. Trolltech also sells licenses for developing proprietary software. When using the free versions, programs which link to Qt must be released as free software (under the GPL or another license permitted by the QPL, such as the BSD or LGPL for example). The core libraries of KDE are collectively licensed under the GNU LGPL, although unless the license of Qt is changed (for example, if the agreement made with the KDE Free Qt foundation is invoked) the only way for commercial software to make use of them is to be developed under the terms of the Qt commercial license.

It is not necessary to use Qt or the KDE libraries to write software which integrates well with the KDE desktop. Software using any other toolkit, following the freedesktop.org standards or using KDE facilities such as KPrinter and KDialog can integrate nicely with the KDE desktop (both KPrinter and KDialog link to Qt, and are under the GPL), however the widgets will not have the exact behavior of Qt widgets. Additional integration efforts are being discussed in the Portland Free Desktop initiative,^[26] and are planned for KDE 4.

Some other free/open source desktop platforms (such as GNOME, Xfce and EDE) use toolkits licensed under the LGPL. The LGPL permits proprietary/closed source applications to link to libraries licensed under the LGPL, with some restrictions: the Section 6 of the LGPL v2.1 prohibits linking to software with a license that restricts reverse-engineering and modification of the work for the customer's own use.^[27] The proprietary Qt license which Trolltech sells does not carry these restrictions.

See also

• Comparison of X Window System desktop environments

References

External links

• The KDE website
• Screenshots of KDE 2.0 showing Kandalf

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