Mark-up and Scripting Languages

There are various forms of coding languages around that are used to create and deploy web pages that are common across the web today. Several years ago, to improve manageability and to allow various web browsers, such as Microsoft Internet Explorer and Netscape Navigator, to interpret and be able to display the same page, a set of standards where released. These standards defined specific languages (both scripts and mark-up) that are used to build web pages. The governing body is known as the World Wide Web Consortium, otherwise referred to as ‘W3C’. As new functionality is introduced, these standards are updated, with new versions periodically released.

Mark-up Languages

The majority of Mark-up languages in use today originate from the meta-language SGML (Standard Generalised Mark-up Language), developed in the early 80’s. SGML contains a variety of mark-up syntaxes that can be used in a wide range of applications. SGML itself is only used to define mark-up languages, and isn’t used itself as a mark-up language. SGML was originally developed to support documentation that is required to be retained for many years, thus allowing it to still be readable by successive technology. The predecessor to SGML was IBM’s GML (generalised Mark-up Language), developed in the 60’s by Charles Goldfarb.

Common Mark-up Languages used in web development:

• HTML

• XML

• DHTML

• XHTML

HTML

The most common mark-up language currently used is HTML (Hyper-Text Mark-up Language) and has been used since the early days of the web, though it has evolved since its first introduction.

XML

In recent time, W3C have also released XML (Extensible Mark-up Language), which is a derivative of SGML. It has been created as a general-purpose mark-up language that is capable of creating special-purpose mark-up languages, to describe various types of data. The main role of XML is in facilitation of sharing data across different systems, in particular web enabled applications.

DHTML

An extension of HTML, Dynamic HMTL offers additional functionality over basic HTML, enabling the inclusion of such things as simple animations and dynamic menus. It can allow a web pages to look and act like desktop applications or multimedia products, by using a mix of CSS (Cascading Style Sheets) & JavaScript. A limitation of DHTML is the varying browser support, which can result in pages failing to render correctly in different browsers. When using DHTML it is important to understand what functionality is supported on which browsers.

XHTML

An updated version of HTML has been developed, called XHTML (Extensible Hyper-Text Mark-up Language). It is far more robust version, requiring all tags to be closed, or have closing tags. The increased control is due to the pages having to conform the XML ‘well-formed’ page standards. All new browsers are XHTML enabled, as it is compatible with HTML 4.01.

Script Languages (web programming)

When building web sites or a web applications, a mark-up language isn’t always enough to produce the functionality required. Therefore a mark-up language is often supplemented with a script language. A script language provides basic programming, usually a subset of a full-blown language.

Common Script Languages used in web development:

• JavaScript

• VBScript

• Jscript

• ASP

• PHP

• XSLT

JavaScript

JavaScript is the most commonly used script language in web pages, and despite its name, it actually has more in common with the Self programming language (used in the 90’s as an experimental system for designing languages), than Java itself. It was developed by Netscape, based on ECMAScript (a standardised script language). JavaScript has evolved over time and is currently at release version 1.5 (as of March 2006), though current versions of Microsoft Internet Explorer (IE 6.0) only support version 1.3.

VBScript

Developed by Microsoft, primarily to aid system administration, the script was incorporated into web design early on, and is now widely used. VBScript is used much in the same way as JavaScript or JScript, though it does offer some functions that aren’t directly present in them, and lacks some of their functionality.

JScript

Developed by Microsoft, primarily as an alternative to JavaScript, this is Microsoft’s interpretation of the ECMAScript standard. Much like JavaScript, though not as widely used.

ASP

ASP (Active Server Pages) was developed by Microsoft to support server-side dynamically generated web pages. It was first supported on Microsoft’s Web Server application, part of IIS (Internet Information Services) that is a free add-on to the Microsoft Windows Operating System. Sun Microsystems have since provided an ASP Server Application to run on other operating systems. It is widely used in commercial applications, and its latest version, ASP.Net, is growing in popularity.

PHP

Originating from series of Perl Scripts, PHP has developed into a fully-fledged scripting language. It is used today to develop dynamic web pages and server-sided applications. PHP is open-source, and so does not require license fees.

XSLT

XSLT (Extensible Stylesheet Language Transformations) is an XML based transformation language. It is used to convert XML documents, primarily data formats between different system schemas.