Wireless Markup Language

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Evolution of mobile web standards

Wireless Markup Language, based on XML, is a markup language intended 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).

1 WML history
2 WML markup
3 Criticism
4 References
5 See also
6 External links

[edit] WML history

Building on Openwave's HDML, and Ericsson's and Nokia's proprietary markup languages for mobile content, the WAP Forum created the WML 1.1 standard in 1998. WML 2.0 was specified in 2001, but has not been widely accepted. The newest WML version in active use is 1.3.

[edit] WML markup

WML documents are XML documents that validate against the WML DTD (Document Type Definition)^[1] . 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>

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 of which represents a single interaction with the user. The introduction of the terms "deck" and "card" into the internet and mobile phone communities was a result of the user interface software and its interaction with wireless communications services having to comply with the requirements of the laws of two or more nations.

WML decks are stored on an ordinary web server trivially configured to serve the text/vnd.wap.wml MIME type in addition to plain HTML and variants. The WML cards when requested by a device are accessed by a bridge WAP gateway, which sits between mobile devices and the World Wide Web, passing pages from one to the other much like a proxy. The gateways radio the WML pages in a form suitable for mobile device reception. 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 locked the phone to prevent access of user-specified URLs.

WML has a scaled down set of procedural elements which can be used by the author to control navigation to other cards.

It is an error and misconception to think of WML as a pinhole view of the Internet. The real magic and value of WML is that it provides an interface with the phone hardware to initiate a call based on web content requested by user query, for example the telephone number of a taxi servicing your zip code:

<card id="cM" title="MY_DOMAIN.com">
<p>
<b>Call A Taxi:</b> <br/>
<a href="wtai://wp/mc;%2B19035551212">
 903-555-1212</a><br/>";
</card>

Mobile devices are moving towards support for greater amounts of XHTML and even standard HTML as processing power in handsets increases. These standards are concerned with formatting and presentation. They do not however address cell-phone or mobile device hardware interfacing.

WML can be a very powerful and effective cell-phone add on. It lets you for example enter a zip code, and obtain a list of clickable phone numbers of pizza parlors and taxicabs in your immediate location.

[edit] Criticism

The acceptance of WML has been limited by the fact that many cell phone providers require separate activation and additional fees for data support, and also because telecommunications companies have sought to limit data access to only "approved" data providers operating under "license" of the signal carrier.

In recognition to the problem, the U.S. Federal Communications Commission (FCC) issued an order on July 31, 2007 which mandates that licensees of the 22-megahertz wide "Upper 700 MHz C Block" spectrum will be required to implement a wireless platform which allows customers, device manufacturers, third-party application developers, and others to use any device or application of their choice when operating on this particular licensed network band.^[2]