Page 48 - DCAP512_WAP_AND_WML

WAP & WML

Notes Web server requests are routed through WAP gateways (proxies). A Web server may generate
WML content for WAP devices or it may simply dish out HTML (XML). In case the Web server
generates HTML (XML), the WAP gateways must convert the HTML (XML) to WML. Before
sending the WML to the WAP device, the gateway compresses it to WMLC (the C in WMLC is for
compressed). If the WML generated by the Web sever is WMLC, then the compression step is
skipped.
Incidentally, converting HTML automatically to WML typically does not produce good or even
usable results. For best results, Web servers should generate WML for WAP devices.

Self Assessment

Fill in the blanks:
1. The Wireless Markup Language (WML) is a simple markup language that was designed
exclusively for the purpose of creating applications to be sent over wireless networks to
…………………….. mobile devices.
2. The web browser is a sophisticated …………………….. that offers a number of flexible and
convenient features for the viewers.
3. …………………….. within the cards of a deck is done within the WAP device just as
scrolling a Web page is done within the Web device.
4. Web server requests are routed through WAP ……………………..
5. In case the Web server generates HTML (XML), the WAP gateways must convert the
…………………… to WML.
6. WML is an open standard and was developed by the WAP forum and the WML specification
forms a part of the broader …………………….. specification.
7. The Web browser manages issues relating to the …………………….. boundaries.

4.2 Getting Started with WML

WML requires a micro browser to interpret the various commands necessary to render a
document, or “deck” as WML documents are called. These browsers are usually embedded in
the mobile device.
Cards and Decks are the two main parts in an WML application. WML applications are composed
of one or more decks, which are containers of collections of cards. Each card typically contains
some content, such as text and images that are displayed to the user, and some other content that
is used by the micro browser to control how the user moves from one card to the next. Also a
card may contain input fields for the user to enter data as we have the form functionality using
HTML in web browsers.
WAP-enabled devices will display a single card at a time. If a card is too large to fit the display
all at once, the device may split the card and show it as a sequence of screens or use some
mechanism such as scroll bars.
Normally, a WML card is similar to an HTML page, but there is no way in HTML for bundling
a collection of pages together. This distinct facility being offered by WML decks is more important
for wireless Internet applications. That is, by combining related cards, several cards can be sent
to microbrowsers at the same time. This has the potential of saving a great deal of time and by
designing applications intelligently, it is feasible to reduce the number of decks to be passed to
devices. If deck is too large, the wireless application developer has to split it up in the most
logical way.

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