Wireless Markup Language
This section provides a brief overview of the Wireless Markup
Language (WML) used in WAP architectures. WML is the official WAP markup
language for exchange of content between wireless terminals and the WAP-enabled
network. The most important design elements of WML are due to the nature of
mobile personal devices with the following characteristics:
While meeting these constraints, WML shares common
characteristics with HTML, which is widely used on the Internet; HDML (Handheld
Device Markup Language), an earlier markup language; and XML (eXtensible Markup
Language). Utilizing features from these different sources, WML is defined with
four major functional areas:
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Text presentation and layout
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Deck/card organization in WML makes all information organized
as decks and cards
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Intercard navigation and linking is used when navigating
between cards and decks
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String parameterization and state management are possible in
WLM decks.
Naming within WML is implemented with uniform resource locator
(URL) to be compatible with WWW naming. The WML character set is derived from
the XML document character set. WML also inherits the syntax information from
XML. WML content can include scripts, and these scripts can be invoked from WML.
The scripting language used here is WMLScript, which is similar to Javascript
but optimized for high-latency, low-bandwidth communications.
WMLScript supports most standard programming constructs and it
can be compiled on the server to yield a byte code executable format, which is
smaller than the text format, so that it is suitable for the radio. WMLScript
matches the WAE requirements for a lightweight language that can be easily
parsed and interpreted, is easy to program, integrates with WML, and is a
well-known language.
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