WAP (Wireless Application Protocol) makes it possible to view Internet pages on the display screen of a WAP-enabled mobile telephone or other wireless device.
WAP pages can be thought of as a simplified version of web pages. Unlike web pages, WAP pages are normally limited to plain text (with some simple styling such as bold and italics) and monochrome images (in WBMP format) on displays that are typically 100 by 40 pixels.
On the web the markup language for documents is HTML (HyperText Markup Language) and web pages will tend to have either an .html or an .htm extension. WAP instead uses the markup language WML (Wireless Markup Language) and WAP files should normally be given the extension .wml. Each WAP document (or "deck") is made up of one or more "cards", and the content of each card is what is normally displayed in the WAP browser window.
Web browsers usually talk directly to a web server to ask for a certain page. In WAP, there is another device involved which is called a WAP gateway. This device sits somewhere on the network between the WAP browser and the web server and helps the web server send data to the WAP browser and vice versa. The WAP gateway will convert the WML code to a compressed format before sending it on to the WAP browser.
For this reason, WML code is much more strict than HTML code and is much less forgiving of small formatting errors.
Here is a very simple example of a WML page:
<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card id="mycard" title="My Card">
<p>Hello world!</p>
</card>
</wml>
There must not be any other characters (not even spaces or newline characters) before the first line of the page.
You can try out your own WAP pages without using a mobile phone, or have a look at some pre-existing WAP sites, using the Wapalizer from Gelon.
There is also a directory of WAP sites available at their site: http://www.gelon.net
If you would like to learn more about WAP we recommend reading the WAP Tutorial provided by W3Schools.com. |
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