Background Information

Communication between a common web server and a WAP-enabled wireless device, in principle, is much the same as that between the web server and the traditional pc-based browser , but with one additional step.

This extra step involves the transfer of information by a WAP gateway. WAP gateways serve as intermediaries between the client-based wireless browser and an information server.

This process is illustrated below:

Consider a typical example of the communications process, as illustrated in the above example: Assume we have defined a deck of two cards. A wireless-device user requests the deck (document). The sequence of events that would take place as a result of this request would be as follows:

1. The request is sent to the WAP gateway under the WAP protocol. The WAP gateway, under the "control" of the WAP device, performs a typical URL request, using HTTP protocol.
2. The URL request is transmitted via the Internet to the WAP device's IP address. (The mobile operator assigns the device its IP address.)
3. The request reaches its final destination – that being a web server. The server, in turn, reads the header and processes the WAP document request. PHP code contained within this document is compiled and formatted as necessary (that is, within the document).
4. The located (and processed) WAP document (deck) is routed back via the WAP gateway, where its contents are compressed into binary data and sent to the WAP-enabled device.

Learning Objectives

In this tutorial you will learn how to:

* Modify the Apache httpd.conf file to accept and serve WML enabled decks.
* Output specific headers via PHP in order to serve WML-enabled decks.
* Pass variables between WML decks.
* Manipulate variables contained within WML decks.
* Make use of basic MySQL functions to provide for database interaction with the wireless web.

You will also be able to apply the following functions:

header(), mail(), include(), date(), mysql_pconnect(), mysql_query(), mysql_fetch_array(),

Overview

Wireless Markup Language (WML) is used to communicate with web browsers embedded within wireless devices and is based on XML.

WML, which operates via a Wireless Application Protocol (WAP), is rapidly gaining popularity among developers such as AOL and Yahoo. WML/WAP technology is being developed to provide wireless users with games, information and email services, instant messaging, and a variety of other applications.

This tutorial shows you how you can use PHP in conjunction with WML to serve dynamic content to a WAP-enabled wireless device.

The sample code illustrates several facets of user interaction via a wireless web browser, including:

* Performing basic insertions of dynamic content (such as a date).
* Sending email.
* Interacting with a MySQL database.

Although PHP-enhanced WML applications can be developed and served on any web server, the Apache web server will be featured in this tutorial as the model from which to do so.

Use Serverside Scrpting Language

We have to use any serverside scripting language to make our WAP site dynamic. I will be using PHP as serverside script.