WML

One of the XML applications that has been getting a lot of attention there days is WML. WML and its associated protocol, the WAP, are targeted at handheld devices such as cellular phones, PDAs, and other devices with restricted hardware capabilities. WML represents a limited-syntax language that's relatively easy to implement for such devices. The programs that use WML in those devices are often called microbrowsers .

Here are some WML resources:

• www.wapforum.org A great resource for all things WML. Acts as a clearinghouse for information. The WAP Forum was consolidated with the Open Mobile Architecture Initiative to form the Open Mobile Alliance Ltd, whose home page is at www.openmobilealliance.org. As of this writing, however, the WAP Forum site is still available.

• www.apachesoftware.com All about Klondike, a popular WML browser.

• www.apachesoftware.com/wml/wmldemo.wml Klondike WML examples.

• http://www.zvon.org/xxl/WMLTutorial/Output/introduction.html A WML tutorial.

• http://www.wirelessdevnet.com/channels/wap/training/wml.html Another WML tutorial.

• http://www.wapforum.org/DTD/wml20-flat.dtd The WML 2.0 (the current version) DTD. A great place to check to resolve syntax questions.

• http://updev.phone.com Openwave's WML SDK, which includes a browser.

You can find the WML 2.0 elements in Table 20-3. You'll find links to the various sections of the WML DTD at http://www.wapforum.org/what/technical.htm, and you can view the whole DTD as one file in http://www.wapforum.org/DTD/wml20-flat.dtd. If you want to check on WML elements or see what attributes an element has, http://www.wapforum.org/DTD/wml20-flat.dtd is a good resource.

Table 20-3. WML 2.0 Elements

Element	Function
a	Hyperlink
abbr	Abbreviation
access	Access element
acronym	Acronym
address	Addresses
anchor	Creates an anchor
b	Bold
base	Base
big	Big text
blockquote	Block quotes
br	Line break
caption	Table caption
card	Creates a card
cite	Citations
code	Code text
dd	Definition description
dfn	Definitions
div	DIV sections
dl	Definition list
do	Do element
dt	Definition term
em	Emphasized
fieldset	Field set
form	Creates a form
getvar	Get variable
go	Navigates
h1 h6	Headings
head	Head section
hr	Horizontal rule
i	Italic
img	Handles images
input	Text field
kbd	Keyboard text
label	Label
li	List item
link	Link
meta	Holds metadata
noop	No operation
object	Object
ol	Ordered list
onevent	Handles an event
optgroup	Creates an option group
option	Creates an option
p	Paragraph
param	Parameter
postfield	Post field data
pre	Preformatted text
prev	Move to previous card
q	Quote
refresh	Handles refreshes
samp	Sample text
select	Select control
setvar	Sets a variable
small	Small text
span	Spans text
strong	Strong
style	Style
sub	Subscript
sup	Superscript
table	Creates a table
td	Table cell data
template	Template
textarea	Text area
timer	Creates a timer
title	Title
tr	Table row
tt	Teletype text
u	Underlined
ul	Unordered list
var	Variables

In addition, WML supports these character entities:

• & is an ampersand ( & ).

• ' is an apostrophe ( ' ).

• > is the greater-than symbol ( > ).

• &lt; is the less-than symbol ( < ).

• &nbsp; is a nonbreaking space ( ).

• &quot; is a quotation mark ( " ).

• &shy; is a soft hyphen ( _ ).

In this chapter, I'll use the popular Apache Klondike WML browser, which you can download for free from links at www.apachesoftware.com. It's a well-designed browser; if you want to follow along, I encourage you to install it.