WAP has been oversold as browsing on your mobile; this is the wrong message to send as the devices are small and the bandwidth is low. Which isn't a problem for good WAP applications, but it kills any pleasure in browsing - because graphics are monochrome and slow to load (unless carefully crafted), interfaces are not standard, navigation is limited, and anyway when you finally get to the page you want there's only a limited amount of information you can convey on a micro-browser's screen. In short: browsing in WAP is an annoying and aggravating experience!
WAP should be used for quickly getting important information. Obviously 'important' depends on the user's priorities, which will change during the day even for one user, but since WAP is expensive at the moment - the information has to be important or the user won't want to get it.
One advantage of WAP over web browsing is that WAP is always available, if the user takes their WAP enabled mobile with them. But to take advantage of this the information needs to be timely, e.g. up-to-date stock market information during the day, traffic information on the way home, perhaps current movie showing times in the evening.
Another important advantage of WAP is that the user's location can be used to determine what to send them. Because WAP is sent to a mobile, the particular active cell gives a neighbourhood, whilst triangulation from adjacent cells (based on received signal strengths) can locate the user to within a few blocks. And in the future GPS (Global Positioning System) will be used to provide your location to within a few metres! A useful current application is to find the address of the nearest bank or post office to where you are now.
Ideally, the user needs to get to the information within 5 key presses, without typing anything, read the information, possibly do something with it, and quit. This is not browsing, but highly focussed information processing.
Micro-browser emulators
You can use these to view WAP pages on your PC, but note you are probably not paying mobile rates to do this! They start at my WAP home page, but you can type any WAP URL (don't forget the trailing '/'). The convention is to put a WAP directory off your top level homepage directory, and a micro-browser will load index.wml (e.g. my WAP home page is www-staff.it.uts.edu.au/~simmonds/WAP/index.wml).
Click on Wapalize for the emulater from www.gelon.net
<= Click here for the WAPJAG emulator from www.wapjag.com
So have a go and compare the web and WAP pages for WAPJAG and gelon. This should leave you in no doubt as to the differences between WAP and web browsing!
WML - Wireless Markup Language
This has many similarities to HTML (Hyper Text Markup Language), the language of the www. But you have to get the coding right or it doesn't work, unlike HTML. For example, paragraphs must be closed and can't be nested. This is partly because it is compiled into binary to save bandwidth, unlike HTML which is sent as an ASCII file and interpreted by your web browser, but also because WML is an XML document standard.
My WAP home page code is here (click on this link with Internet Explorer or Netscape and it shows the WML code, not how it would appear on a micro-browser or emulator).
WAP protocols compared to web protocols and OSI layers
| WAP | Web | OSI layer |
| Micro-browser, WAP phone, PDA | Web browser | User Application |
| WAE - Wireless Application Environment (WML + WMLScript) | HTTP | 7 - Application layer |
| WML - Wireless Markup Language WMLScript WBMP - WAP BitMap WTLS - Wireless Transport Layer Security | HTML Java Script JPEG SSL | 6 - Presentation layer - Scripting - Graphics - Security |
| WSP - Wireless Session Layer | (TCP) | 5 - Session layer |
| WDP - Wireless Datagram Layer | TCP, UDP | 4 - Transport layer |
| Bearer services | IP | 3 - Network layer |
The bearer service could be SMS (Short Message System), GSM (Global System for Mobile communication), GPRS (General Packet Radio Service), or other services. Basically, GPRS is better than GSM is better than SMS.
Of course, WAP doesn't quite fit the OSI seven layer reference model: e.g. the 'WAP application layer' is WAE - the Wireless Application Environment ( = WML + WMLScript), which is the presentation layer as well.
Resources
I found 'WAP: A Beginner's Guide' by Dale Bulbrook, pub. Osborne/McGraw-Hill, 2001, to be an excellent and very readable introduction to the subject.