computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...

and

web development Web development is the work involved in developing a website for the Internet (World Wide Web) or an intranet (a private network). Web development can range from developing a simple single static page of plain text to complex web applications ...

, XML Events is a

W3C The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web. Founded in 1994 and led by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working to ...

standard for handling

events Event may refer to: Gatherings of people * Ceremony, an event of ritual significance, performed on a special occasion * Convention (meeting), a gathering of individuals engaged in some common interest * Event management, the organization of ev ...

that occur in an

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...

document. These events are typically caused by users interacting with the web page using a device, such as a

web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on ...

on a

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...

mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...

Formal definition

An XML Event is the representation of some

asynchronous Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal with ...

occurrence (such as a mouse button click) that gets associated with a data element in an

document. XML Events provides a static, syntactic binding to the DOM Events interface, allowing the event to be handled.

Motivation

The XML Events standard is defined to provide XML-based languages with the ability to uniformly integrate event listeners and associated

event handlers In programming and software design, an event is an action or occurrence recognized by software, often originating asynchronously from the external environment, that may be handled by the software. Computer events can be generated or triggered ...

with

Document Object Model The Document Object Model (DOM) is a cross-platform and language-independent interface that treats an XML or HTML document as a tree structure wherein each node is an object representing a part of the document. The DOM represents a document wi ...

(DOM) Level 2 event interfaces. The result is to provide a declarative, interoperable way of associating behaviors with XML-based documents such as

XHTML Extensible HyperText Markup Language (XHTML) is part of the family of XML markup languages. It mirrors or extends versions of the widely used HyperText Markup Language (HTML), the language in which Web pages are formulated. While HTML, prior ...

Advantages of XML Events

XML Events uses a

separation of concerns In computer science, separation of concerns is a design principle for separating a computer program into distinct sections. Each section addresses a separate '' concern'', a set of information that affects the code of a computer program. A concern ...

design pattern A design pattern is the re-usable form of a solution to a design problem. The idea was introduced by the architect Christopher Alexander and has been adapted for various other disciplines, particularly software engineering. The " Gang of Four" b ...

, and is technology-neutral with regard to handlers. It gives authors freedom in organizing their code and allows separation of document content from scripting.

Legacy In law, a legacy is something held and transferred to someone as their inheritance, as by will and testament. Personal effects, family property, marriage property or collective property gained by will of real property. Legacy or legacies may refer ...

HTML The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScri ...

and early SVG versions bind events to presentation elements by encoding the event name in an

attribute Attribute may refer to: * Attribute (philosophy), an extrinsic property of an object * Attribute (research), a characteristic of an object * Grammatical modifier, in natural languages * Attribute (computing), a specification that defines a prope ...

name, such that the value of the attribute is the action for that event at that element. For example, (with

JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side ...

’s ''onclick'' attribute):


Stay here!

This design has three drawbacks: # it hard-wires the events into the

language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of met ...

, so that adding new event types requires changes to the language # it forces authors to mix the content of the document with the specifications of the scripting and event handling, rather than allowing them to separate them. # it restricts authors to a single

scripting language A scripting language or script language is a programming language that is used to manipulate, customize, and automate the facilities of an existing system. Scripting languages are usually interpreted at runtime rather than compiled. A scripting ...

per document.

Relationship to other standards

Unlike DOM Events, which are usually associated with HTML documents, XML events are designed to be independent of specific devices. XML Events are used extensively in

XForms XForms is an XML format used for collecting inputs from web forms. XForms was designed to be the next generation of HTML / XHTML forms, but is generic enough that it can also be used in a standalone manner or with presentation languages other tha ...

and in version 1.2 of the SVG specification, , which is still a working draft.

Example of XML Events using a listener in XForms

The following is an example of how XML events are used in the XForms specification: Do it! In this example, when the DOMActivate event occurs on the data element with an id attribute of myButton, the handler doit (for example, a JavaScript element) is executed.

References

External links

W3C XML Events Specification
was
W3C Recommendation on 14 October 2003

W3C XML Events for HTML Authors
tutorial {{DEFAULTSORT:Xml Events World Wide Web Consortium standards XML