WML (Wireless
Markup Language) Introduction
What
is WML 1.x?
WML
(Wireless Markup Language) 1.x is the markup language defined in the
WAP 1.x specification. WAP is the standard created by the WAP Forum
(now the Open
Mobile Alliance [OMA]) that brings the World Wide Web
to wireless devices. It specifies the protocol stack and application
environment of mobile Internet browsing applications.
The
role of WML in mobile Internet applications is the same as that of
HTML in web applications. WAP sites are written in WML, while web
sites are written in HTML.
WML
1.x is very similar to HTML. Both of them use tags and are written in
plain text format. Some tags in WML 1.x are directly borrowed from
HTML. If you have experience in using the HTML markup language, you
should be able to learn WML 1.x quickly.
Some
features of WML 1.x are specific to wireless devices. For example,
WML 1.x provides a way for developers to program the softkeys of
mobile phones. This feature is not supported in HTML since computers
do not have any softkeys.
The
most up-to-date version of the WAP 1.x specification is WAP 1.2.1,
which defines WML 1.3.
WML
files have the extension ".wml". The MIME type of WML is
"text/vnd.wap.wml".
WML
supports client-side scripting. The scripting language supported is
called WMLScript. Its syntax is based on JavaScript. If you want to
learn it, our WMLScript tutorial
will be a good starting point for you.
WAP
2.0
WAP
1.x is an earlier version of the WAP standard. The most current
version is WAP 2.0. The markup language defined in WAP 2.0 is XHTML
MP (XHTML Mobile Profile). It is a subset of the XHTML used on the
web. XHTML MP supports a mobile version of cascading style sheet
called WCSS (WAP CSS). It is a subset of the CSS2 used on the web
plus some WAP specific extensions.
Most
of the new mobile phone models released are WAP 2.0-enabled. As WAP
2.0 is backward compatible to WAP 1.x, WAP 2.0-enabled mobile devices
can display both XHTML MP and WML documents.
WML
1.x is an earlier technology. However, that does not mean it is of no
use, since a lot of wireless devices that only supports WML 1.x are
still being used. Besides, some useful features of WML are not
available in XHTML MP. For example, XHTML MP does not support events,
variables and client-side scripting. The major WML features lost in
XHTML MP are discussed in the "WML
Features Lost in XHTML MP" section of our XHTML
MP tutorial.
If
you write the markup of your mobile Internet site in WML, both old
and new WAP-enabled wireless devices can be used to view your mobile
Internet site. The user base of your WAP application is maximized.
WML
2.0
WAP
site developers need not to care about WML 2.0. WML 2.0 is created
for backward compatibility purposes and it is not for use by WAP site
developers. To develop a WAP site with the WAP 2.0 standard, use
XHTML Mobile Profile.
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