How do I start writing WAP applications?

All you really need is a text editor still, you’ll find that using a developer toolkit can save you lots of time until you get used to the WAP environment.

WAP FORUM is where the initial WAP 1 specifications were defined. The site still exists, but you probably want to go to the more updated Open Mobile Alliance (A.K.A. OMA) site.

Registering yourself with the Nokia WAP Developer Forum and then downloading for instance the Nokia Mobile Internet Toolkit 4.1 should probably be one of your first steps. The toolkit comes with PDF files that will give you references on the WML and WMLScript command syntax and general WAP insight. The Nokia kit requires JRE (Java Runtime Environment) v.1.4.1_02 or higher. A link is available at the same location.

Note that a toolkit might be designed for developing applications for WAP devices in general, not mobile phones in particular. What you make with a WAP developer kit may look nothing like what you get when you use an actual micro browser in a mobile phone. To be sure things look the way you want, you either need the actual WAP device, such as a mobile phone, or an emulator.

The structure of Nokia resources is somewhat complicated, the browsers, WAP emulators and MMS simulators work as plug-ins to the Nokia Mobile Internet Toolkit. Older emulators like the 7110, 6210, 3330, 3390 or 8310 do not work with NMIT 4.1, start with the ones listed with the toolkit. A must to read is the datasheet of Nokia Mobile Internet Toolkit. The toolkit also includes a WAP Gateway Simulator whose logs list the details of the communication with the emulator. Unlike some other emulators, Nokia relies on a WAP gateway to connect to external internet addresses, so either the Nokia (default) or another gateway must be configured in.

Register and check out the Openwave.com developers’ site. Openwave.com provides the UP.browser which is as far as I know the most widely used browser, especially in the US. Openwave.com provides a Phone Simulator available for download. Older Simulator versions are also available, for debugging WML is UP.SDK 4 still the best version. This page helps to understand which Openwave SDK is best for you.

SonyEricsson provides a good developers' site too. Unfortunately it seems like they are not providing an emulator anymore.

Motorola has development tools for both WAP and Motorola's VoxML. After you have registered you can download all the software.

YOSpace provides SmartPhone Emulator Developer Edition (a development kit) and SmartPhone Emulator Web Site Edition, a java applet to show mobile sites from a standard browser. Very useful when you want to show a mobile version of your web site.

Winwap is a windows application that lets you browse mobile sites from your PC.

The open-source WURFL (and WALL) libraries/tools site is a useful position to start too. It will provide you with insights into what makes devices different, how to differentiate between them and links to many resources concerning the challenges (and their solutions) mobile designers face when trying to cater to many devices at once. Finally there is the WALL library, which provides a very useful mobile markup ‘meta language’ which aims to combine your markup and the calling device info into an optimized version of the page to send back.

If you are developing applications for the public, you will want to test these applications on as many WAP devices (or their emulators) as possible. Just as you would test your HTML documents on several browsers. Note that the differences between two WML micro browsers will be much more noticeable than the differences between two HTML browsers.