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Why learn it?

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Why learn it?

There were more than 1.2 billion mobile telephones in 2004 devices in the world and many of those devices have the capability to connect and use Internet services. To efficiently and reliably connect to the Internet, these devices use markup languages.

Markup languages use text based communications messages to describe formatting and item selection features to be transferred independent of the type of computer system. One of the first markup languages used in the Internet is Hypertext Markup Language (HTML).

HTML was developed for use with PC-based web browsers, and as a language it is concerned with layout and placement of images on pages. Because HTML was not designed for use with mobile devices that commonly have poor quality communication links and limited amount of data transmission, Handheld Device Markup Language (HDML) was developed. HDML is optimized for low bandwidth operation using limited screen size and limited user input keys. HDML allows soft keys to be dynamically defined to allow a phone and return the key presses to the network application Unwired Planet developed HDML. In 1997 when the WAP Forum was formed, it created WML, replacing HDML.

XHTML Basic was developed as a language to program wireless devices by World Wide Web Consortium (W3C). It was initiated to provide a common markup language to use for wireless devices in December 2000.

XML differs from WML or XHTML in that XML is a language for creating markup languages. XML allows document authors to create their own markup for virtually any type of information. Therefore, authors can use XML to create entirely new markup languages to describe specific types of data, including mathematical formulas, chemical formulas, music and recipes.

Table 1.1 shows how the Extensible Markup Language (XML) is also as a root language to some of the currently used wireless markup languages. As shown, Hypertext Markup Language (HTML) and Handheld Device Markup Language (HDML) were the original two markup languages and these languages have evolved through multiple revisions. This diagram shows that WML was created to replace HDML and allow mobile devices to access XML content. This example shows that xHTML combines the benefits of HTML and WML.

Table 1.1: Chart of the Markup Tree
Click To expand

While all three languages currently exist in the wireless world, OMA is trying to consolidate these languages and is developing a specification for WAP 2.0, which encompasses two of the three languages – XHTML Basic and WML 1. WAP 2.0 specifies WML 2, which encompasses XHTML Basic, and will be backward compatible to WML1. It utilizes standards developed by W3C, and adopts XHTML Basic and CSS Mobile Profile as part of WML2.

cHTML is still being used for i-mode devices, but is not as widely used as XHTML Basic and WML. In the future, since cHTML is based in HTML, it could very likely merge with a form of WAP or XHTML.

For anyone interested in programming wireless devices today, learning XHTML Basic makes a lot of sense since it is part of the WAP 2.0 Specification, and it is very similar to HTML, and therefore easy to learn. Also, due to the similarity with cHTML, if a person learns XHTML Basic, he can very easily learn cHTML.


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