Wap Introduction

Brief Introduction to WAP

By : Satish Doranahalli
Published on : 09-October-2007

Coding and viewing the pages on mobile device always interests to me, thought to share something about WAP

The Wireless Application Protocol

The WAP protocol is the leading standard for information services on wireless terminals like digital mobile phones.The WAP standard is based on Internet standards (HTML, XML and TCP/IP). It consists of a WML language specification, a WMLScript specification, and a Wireless Telephony Application Interface (WTAI) specification.The WAP Forum founded in 1997 by Ericsson, Motorola, Nokia, and Unwired Planet publishes WAP. Forum members now represent over 90% of the global handset market, as well as leading infrastructure providers, software developers and other organizations.

Protocol Structure

The WAP protocol family mirrors the layered OSI stack, and like the OSI stack some layers are not mandatory. At the lowest level, the WAP Datagram Protocol (WDP) moves information from receiver to sender and is modeled after UDP as a least effort method of delivery. On top of WDP sits the WAP Transaction Protocol (WTP) which ensures that the data fragments sent over the line are actually received, through typical ACK/NACK communication. Higher up, the WAP Session Protocol (WSP) handles the session between communicating systems. All sessions are granted unique IDs and are started/stopped/terminated accordingly.

WAP Micro Browsers

To fit into a small wireless terminal, WAP uses a Micro Browser.A Micro Browser is a small piece of software that makes minimal demands on hardware, memory and CPU. It can display information written in a restricted mark-up language called WML. The Micro Browser can also interpret a reduced version of JavaScript called WMLScript.

What is WML?

WML stands for Wireless Markup Language. It is a mark-up language inherited from HTML, but WML is based
on XML, so it is much stricter than HTML.WML is used to create pages that can be displayed in a WAP browser. Pages in WML are called DECKS. Decks are constructed as a set of CARDS.

What is WMLScript?

WML uses WMLScript to run simple code on the client. WMLScript is a light JavaScript language. However, WML scripts are not embedded in the WML pages. WML pages only contain references to script URLs. WML scripts need to be compiled into byte code on a server before they can run in a WAP browser.

In General uses of WAP

- Checking train table information
- Ticket purchase
- Flight check in
- Viewing traffic information
- Checking weather conditions
- Looking up stock values
- Looking up phone numbers
- Looking up addresses
- Looking up sport results

In my next article I will write about how the simple, tiny, light weight pages are created and how the navigation between the pages are done.