By now, you should have a pretty good idea of what WAP has to offer. But how do you begin developing and deploying your own applications? This is accomplished through two languages, HDML and WML.

HDML (Handheld Device Markup Language)
As you already know, HDML played (and still does) and integral role in the WAP standard. It is fairly similar to HTML, but is strictly written. Strictly written means that the rules cannot be bent as easily as they can be using HTML. Thus, careful coding is a must if no errors are to occur. HDML is specifically written for the WAP interface, and cannot be viewed using the typical web browser. This is somewhat of a drawback, since two separate pieces of code must be written if the developer is interested in producing the same content across both the typical web platform and to the WAP browser. The language is under aggressive development, and is quite capable of offering a wide variety of services to the user.

Phone.com (http://www.phone.com) offers a number of very comprehensive guides and tutorials regarding HDML implementation and development.

WML (Wireless Markup Language)
WML is a markup language built specifically for communicating across WAP-based networks, and is based upon XML (eXtensible Markup Language). Like HDML, it is at first glance similar to HTML, but is also a much more strictly written language.

To make it possible for web pages to be read from a WAP-enabled device, WML must be used. The WML coder determines within the code what parts of the web page are viewable to the device, and what is not. For example, it would not be too advantageous for a 468x60 pixel banner to be loaded into the small screen of a WAP device, due to size, color and bandwidth restraints. However, certain parts of the text may be made available to the device.

The advantage of the WML language is the fact that, since it is a subset of XML, developer's can easily kill two birds with one stone by building both the web page and wireless device page simultaneously. While this is still possible with HDML code, it is certainly not as obvious and workarounds must be introduced.

There are a number of WML-specific sites and guides available on the web. Links to many of the better resources can be found on the next page of this article.