What is it?
Mobile devices such as smartphones and PDAs have significant limitations compared with desktop systems: small screens; cramped keyboards based on phone keypads, rather than the traditional Qwerty layout; limited memory and storage; and low transmission speeds. Working within these constraints, wireless programmers have to try to match the experience Internet users get from their desktop systems.
Some wireless applications are simply extensions of existing Web services - like evolving e-commerce into m-commerce - but some are written specially for mobile devices. Location-based services, for example, exploit the ability of cellular networks to pinpoint the positions of callers. Users can find out about nearby amenities such as hotels and restaurants, and businesses can bombard them with offers and advertising as they walk past their premises.
Mobile games are expected to be a boom area but, like many other wireless applications and services, these will require third generation (3G) networks.
Where did it originate?
The Wap (Wireless Application Protocol) Forum was set up in 1997 by leading handset manufacturers to create standards for wireless Internet access. More recently, Sun weighed in with J2ME (Java 2 Micro Edition) for mobile devices.
What's it for?
Wap is essentially a browser technology for mobile devices. It is a licence-free standard that is available to anyone who wants to develop wireless applications. However, Wap lacks the functional richness of other development environments, which is why J2ME is seen as a complementary technology rather than a competitor. Toolkits from Ericsson, Nokia, IBM and others include both.
What makes it special?
Despite the Wap Forum's claim to openness, Wap 1.0 had little in common with mainstream Internet technologies. The Wap Forum has been working with bodies including the World-Wide Web Consortium and the Internet Engineering Task Force to remedy this, and Wap 2.0 builds on the XHTML, TCP/IP and HTTP standards.
What does it run on?
Wap applications can be built on any mobile operating system, including Windows CE, Palm OS, Epoc, and Java OS.
J2ME runs on any device with a Java Virtual Machine.
How difficult is it?
Wap developers must get to grips with Wireless Markup Language (WML), which is a subset of XML, although you will soon be able to build Wap applications in HTML and XML.
Java developers should be able to adapt to J2ME with ease.
Where is it used?
Most of the wireless applications and services that have been promised remain at the Powerpoint stage, pending 3G networks. The demand created by the hype about Wap is being met instead by SMS (Short Message Service), which has spread from text messaging to mobile data services, games and advertising.
Few people know that
Users rarely wait more than eight seconds for a page to download. Using current technologies, this limits Wap page sizes to about 8Kbytes.
What's coming up?
Wap 2.0 was launched in August this year. The first 3G phones appeared in Japan in September.
Wap Forum members such as Ericsson and Nokia offer training, and Sun is the obvious place to go for J2ME. But there are also plenty of free resources available.
For the most exhaustive list of free wireless and Wap tutorials click here, and www.j2me.org/ for wireless Java. Try also www.wirelessdevnet.com/ and www.ibm.com/developerworks.
Rates of pay
Wap and J2ME are premium skills, with many developer jobs commanding salaries of £30,000 to £45,000.