Get started with WML
Harshad Oak, Builder.com on August 6th, 2002 (August 6th, 2002)
WML is to WAP what HTML is to
HTTP. However, because of the lack of bandwidth and the
minimum capability of WML browsers embedded in mobile phones,
WML has been developed into a much slimmer language, shedding
all the features of HTML that would be useless for wireless
devices. Let’s take a closer look at WML.
Shuffle the deck
The WML
parallel of an HTML page is termed a deck. So when you
try to access a WAP site using any WAP-enabled device, what is
actually getting to your device is a deck. A deck can be
broken down into cards. In fact, what is visible at a glance
is one card and not an entire deck. These cards can link to
other cards, and navigating to other cards is possible
programmatically as well as in response to user
input.
A deck is the smallest unit that can be sent by
the server to a WAP client, and it can contain one or more
cards. Listing A contains a sample WML
file.
This
example is a basic WML deck containing three cards. The card
with the id "first" is, not surprisingly, the one that is
displayed first. Although the other cards also come to the
client as part of the deck, they are not initially visible. On
clicking the Click Here link, the second card is visible. It
has an image and an embedded list box.
What is
interesting is the use of $(OS) in the third card. OS
here refers to the list box name on the second card. Hence,
based on selection made on the second card, the message on the
third card can change.
The WAP
toolbox
If you are wondering how in the world you
are going to check out how this WML content would be displayed
on a mobile phone, fret not. More than a handful of WAP
simulators and development tools exist. The best of the lot
seems to be the
WAP Toolkit provided by Nokia. Since Nokia is ubiquitous
in the mobile market, you surely want your WML pages to be
displayed properly on its handset.
If you are using
Macromedia Dreamweaver, a pretty nifty way to get your WML
pages done in no time would be to get hold of the Nokia WML
Studio plug-in for Dreamweaver. It makes WML development with
Dreamweaver a cinch.
Most of the leading handset
providers, such as Ericsson and Motorola, have toolkits that
can simulate how your page will look on their respective
handsets. If you are looking for a basic editor that will
quickly get some pages up, Coffee Cup Wireless
Web Builder is a solid product that includes an
easy-to-use WML page creator.
Jazz
up your WML
Pure text pages are boring. To spice up
your WML pages, you need well-placed but sparingly used WBMP
images. WBMP is the WAP image standard format. Creating WBMP
images is definitely not a tough task, but you can get tons of
images that suit your purpose from the Net. If you are still
keen on creating your own images, try your hand at the WBMP
image maker included with the Coffee Cup Wireless Web
Builder.
Gathering
data
Dynamic pages that send data to the server are
pretty much essential for you to do anything worthwhile on the
Net these days, so WML needs the capability to submit user
data.
There is no direct HTML <form> tag parallel
in WML. To submit data, you use postfields, and you use the $
sign to fetch user input and pass it on to the specified href.
Listing B provides an example. Upon
clicking Submit to Servlet, the data that's been entered in
the Login and Password fields would be passed on to the
specified servlet. So if I enter Harshad in the Login
field and Oak as my password, on submission, my query
string should look something like
http://localhost:8080/AbcServlet?loginName=Harshad&loginPass=Oak&msg=HELLO
WAP yourself into shape
Get going
with WML and make your presence felt in the wireless world. A
significant advantage of having WAP expertise is that although
it is pretty easy to latch on to, it still is rather rare in
the technical marketplace.
Are you working with wireless
technologies?
Share your
wireless development experience with the Builder.com community
by posting in the discussion below or send
us an e-mail.
URL:http://www.zdnetasia.com/get-started-with-wml-39070011.htm