Wireless Markup Language
From Wikipedia, the free encyclopedia
Wireless Markup Language, based on XML, is a content format for devices that implement the Wireless Application Protocol (WAP) specification, such as mobile phones, and preceded the use of other markup languages now used with WAP, such as XHTML and even standard HTML (which are gaining in popularity as processing power in mobile devices increases).
WML documents are XML documents that validate against the WML (currently version 1.3) DTD (Document Type Definition). The W3C Markup Validation service (http://validator.w3.org/) can be used to validate WML documents (they are validated against their declared document type).
For example, the following WML page could be saved as "example.wml":
<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//PHONE.COM//DTD WML 1.1//EN"
"http://www.phone.com/dtd/wml11.dtd" >
<wml>
<card id="main" title="First Card">
<p mode="wrap">This is a sample WML page.</p>
</card>
</wml>
WML pages are stored on a web server. They are accessed by a WAP gateway, which sits between mobile devices and the World Wide Web, passing pages from one to the other much like a proxy. This translates pages into a form suitable for mobiles. This process is hidden from the phone, so it may access the page in the same way as a browser accesses HTML, using a URL (for example, http://example.com/foo.wml), provided the mobile phone operator has not specifically prevented this.
Wireless Markup Language is a lot like HTML (Hyper Text Markup Language) in that it provides navigational support, data input, hyperlinks, text and image presentation, and forms. A WML document is known as a “deck”. Data in the deck is structured into one or more “cards” (pages) – each which represents a single interaction with the user. WML has a scaled down set of procedural elements which can be used by the author to control navigation to other cards.
Mobile devices are moving towards support for greater amounts of XHTML and even standard HTML as processing power in handsets increases. It is likely WML will be phased out in the future.
