XUL (pronounced zool ([zu:l])), the XML User Interface Language, an XML user interface markup language developed by the Mozilla project, operates in Mozilla cross-platform applications such as Firefox and Flock. The Mozilla Foundation is a Non-profit organization that exists to support and provide leadership for the Open source Mozilla project A markup language is an Artificial language using a set of annotations to text that give instructions regarding the structure of text or how it is to be displayed Don't change "Extensible" A user interface markup language is a Markup language that renders and describes graphical User interfaces Many of these markup languages are dialects of Mozilla was the official public original name of Mozilla Application Suite by the Mozilla Foundation, currently known as SeaMonkey suite. Flock is a Web browser built on Mozilla’s Firefox Codebase that specializes in providing social networking and Web 2 The Gecko layout engine provides the only complete implementation of XUL. Gecko is a Layout engine currently developed by Mozilla Corporation, known as the layout engine of the Firefox web browser Mozilla Application

Design

XUL relies on multiple existing web standards and technologies, including CSS, JavaScript, and DOM. JavaScript is a Scripting language most often used for Client-side web development The Document Object Model ( DOM) is a platform- and language -independent standard Object model for representing HTML or XML and related Such reliance makes XUL relatively easy to learn for people with a background in web-programming and design. XUL and web-developer documentation is available online at the Mozilla Developer Center [1]. Mozilla Developer Center ( MDC) started in early 2005 is the official Mozilla Foundation Website for development documentation and news about Firefox

XUL has no formal specification or interoperable non-Gecko implementations. Gecko is a Layout engine currently developed by Mozilla Corporation, known as the layout engine of the Firefox web browser Mozilla Application However, its implementation (Gecko) is open source, tri-licensed under the GPL, LGPL, and MPL. Open source is a development methodology which offers practical accessibility to a product's source (goods and knowledge Dual-licensing is the practice of distributing Software under two different sets of terms and conditions The GNU Lesser General Public License (formerly the GNU Library General Public License) or LGPL is a Free software license published by the Free Software The Mozilla Public License (MPL is a free and Open source Software license. ^[1]

Mozilla provides experimental XULRunner builds to let developers build their applications on top of the Mozilla application framework and XUL in particular. XULRunner is a Runtime environment developed by the Mozilla Foundation for providing a common back-end for XUL applications The Mozilla application framework is a collection of Cross-platform software components that make up the Mozilla applications It was originally

As its main benefit, XUL provides a simple and portable definition of common widgets. See also Software portability In Computer science, porting is the process of adapting software so that an executable program can be created In computer programming a widget (or control) is an element of a Graphical user interface (GUI that displays an information arrangement changeable by the user This reduces the software development effort in a way analogous to the savings offered by 4GL tools. Software development is the translation of a user need or marketing goal into a Software product Analogy is both the cognitive process of transferring Information from a particular subject (the analogue or source to another particular subject (the target and A fourth-generation programming language (1970s-1990 (abbreviated 4GL) is a Programming language or programming environment designed with a specific purpose in mind

XUL documents

Programmers typically define a XUL interface as three discrete sets of components:

1. Content: the XUL document(s), whose elements define the layout of the user interface.
2. Skin: the CSS and image files, which define the appearance of an application.
3. Locale: the files containing user-visible strings for easy software localization. In Computing, Internationalization and localization (also spelled internationalisation and localisation, see spelling differences) are means of adapting

XUL elements

XUL defines a wide range of elements, which roughly belong to the following types:

Top-level elements

e. g. , window, page, dialog, wizard, etc. In Computing, a window is a visual area usually rectangular in shape containing some kind of User interface, displaying the output of and allowing input for one In Graphical user interfaces a dialog (or dialogue) box is a special window, used in user interfaces to display Information to the A wizard is a User interface element where the user is presented with a sequence of dialog boxes.

Widgets 

e. g. , label, button, text box, list box, combo box, radio button, check box, tree, menu, toolbar, group box, tab box, color picker, spacer, splitter, etc. In Computing, a button (sometimes known as a command button or Push button) is a widget that provides A text box, text field or text entry box is a common element of Graphical user interface of computer programs as well as the corresponding type A combo box is a commonly-used GUI widget. It is a combination of a Drop-down list or List box and a single-line textbox, allowing A radio button or option button is a type of Graphical user interface widget that allows the user to choose one of a predefined set of options In Computing, a check box ( checkbox, tickbox, or tick box) is a Graphical user interface A tree view or an outline view is a Graphical user interface element ( widget) that presents a hierarchical view of information In Computing and Telecommunications a menu is a list of commands presented to an operator by a Computer or Communications system. In a Graphical user interface on a Computer monitor a toolbar is a panel on which onscreen buttons icons menus or other input or output elements are placed In Graphical user interfaces a tab is a navigational widget for switching between sets of controls or Documents.

Box model

e. g. , box, grid, stack, deck, etc.

Events and Scripts

e. g. , script, command, key, broadcaster, observer, etc.

Data source

e. g. , template, rule, etc.

Others

e. g. , overlay (analogous to SSI, but client side and more powerful), iframe, browser, editor, etc. Server Side Includes (SSI is a simple Server-side scripting language used almost exclusively for the web.

One can use elements from other applications of XML within XUL documents, such as XHTML, SVG, and MathML. The Extensible Hypertext Markup Language, or XHTML, is a Mathematical Markup Language ( MathML) is an application of XML for describing mathematical notations and capturing both its structure and content

Mozilla added some common widgets — <scale/> (sometimes called slider), <textbox type="number"/> (spinbox), time and date pickers — during the Gecko 1. 9 development-cycle. ^[2]

XUL applications

While XUL serves primarily for creating the Mozilla applications and their extensions, it may also feature in web-applications transferred over HTTP. In Software engineering, a web application or webapp is an application that is accessed via Web browser over a network such as the Internet Hypertext Transfer Protocol ( HTTP) is a Communications protocol for the transfer of information on the Internet. One of the most well-known XUL applications of this type, the Mozilla Amazon Browser, provides a rich interface for searching books at Amazon.com. Amazoncom Inc ( is an American electronic commerce ( E-commerce) company in Seattle Washington.

However, many of the powerful features of Mozilla such as privileged XPCOM objects remain unavailable to unprivileged XUL documents unless the script has a digital signature, and unless the user obtains grants of certain privileges to the application. XPCOM (Cross Platform Component Object Model is a Cross platform component model from Mozilla. A digital signature or digital signature scheme is a type of asymmetric cryptography used to simulate the security properties of a handwritten Signature Such documents also suffer from various limitations of the browser, including the inability to load remote XUL, DTD, and RDF documents.

As Gecko provides the only full implementation of XUL, such applications remain inaccessible to users of browsers not based on Mozilla. Gecko is a Layout engine currently developed by Mozilla Corporation, known as the layout engine of the Firefox web browser Mozilla Application

ActiveState's Komodo IDE uses XUL as well as the recently announced Open Komodo Project http://openkomodo.com .

The Songbird music-player and Miro video-player both use built-in XUL.

Mozilla-programmers sometimes refer to XUL applications running locally as "chrome". ^[3]

The name

The XUL name references the film Ghostbusters (1984), in which the ghost of an ancient Sumerian deity called Zuul possesses the character Dana Barrett (played by Sigourney Weaver) and declares, "There is no Dana, only Zuul". Zuul redirects here For the videogame see Zool. Ghostbusters (titled on-screen as Ghost Busters) is Sumer ( Sumerian: sux-Latn [[Ki (earth ki]]-[[EN (cuneiform en]]-'''ĝir15''', Akkadian: Šumeru; possibly Biblical Shinar Zu, or Anzu in Persian and Sumerian, (from An "heaven" and Zu "far" in the Sumerian language) is a Sigourney Weaver (born October 8, 1949) is an Academy Award -nominated American actress, best known for her roles as Lt Since XUL, unusually, uses XML to define an interface rather than a document, its developers adopted the slogan: "There is no data, there is only XUL". Hence the XML namespace URI at the beginning of every XUL document:

http://www. XML namespaces are used for providing uniquely named elements and attributes in an XML instance mozilla. org/keymaster/gatekeeper/there. is. only. xul

When viewed with a XUL-capable application, the document pointed to displays the slogan in large letters in the center of the screen (similar to that to the right).

"Keymaster" and "gatekeeper" also refer to the same film plotline. Other references to Ghostbusters also occur within Mozilla products: for instance, the JavaScript has a debugger component called Venkman, after one of the main characters in the film. A debugger is a Computer program that is used to test and Debug other programs Venkman is the JavaScript Debugger component of the Mozilla Application Suite. Peter Venkman, PhD is a fictional Scientist and member of the Ghostbusters appearing in the films Ghostbusters and Ghostbusters

Example code

An example XUL dialog box

This piece of code shows 3 buttons stacked on top of each other in a vertical box container:^[4]

<?xml version="1. 0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
 
<window id="vbox example" title="Example"
xmlns="http://www. mozilla. org/keymaster/gatekeeper/there. is. only. xul">
 
<vbox>
  <button id="yes" label="Yes"/>
  <button id="no" label="No"/>
  <button id="maybe" label="Maybe"/>
</vbox>
 
</window>

See also

• XBL
• Mozilla application framework
• XULRunner
• Layout manager
• List of user interface markup languages
• Comparison of user interface markup languages
• OpenLaszlo

References

External links

• XUL documentation on developer. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 51 - Nero, later to become Roman Emperor, is given the title Princeps iuventutis (head of the youth mozilla. org
• XULPlanet — A developer site with tutorials, references and forums
• XUL Periodic Table — Visual demonstration of XUL capabilities (Requires an XUL-enabled browser such as Mozilla Firefox)
• XUL and XML — How to use XUL