Mobile Phone Technology

The mobile internet became available around 1999. The first phones, such as the Nokia 7110, had monochrome screens, limited memory and slow processors, and used either a dial-up GSM network or the later GPRS network. At that time, the 'desktop' internet was well developed. It was unrealistic to expect to be able to use the same TCP/IP - or HTML-based internet on these phones. They did not have the necessary power. To overcome this, the WAP protocol was developed. Designed as a 'lighter' protocol with fewer overheads than TCP/IP, it was less general purpose.

Rather than using HTML, a new language called WML was developed. This was based on the novel concept of a page being a 'deck' of 'cards'. With one call to the server, a number of cards are delivered to the phone, with the first card displayed on the device. Local navigation enables users to move between cards without making another call to the server. The trick, then, was to deliver as many cards as possible in a single server call. However, the 1.4 KB memory limitation ensured that the number of cards remained limited. The WML language enabled text and links to other pages or cards to be displayed. Minimal styling is included. A simple monochrome image format (WBMP) was also specified, but in practice this was not ideal. For input, there was some 'on-phone' validation of data using WMLScript. This also reduced the number of server calls required. The language natively supported making phone calls or sending SMS messages. The scripting language (WMLScript) allows for some local processing, but this is also limited.

Although most WML examples show static code, WML can be generated via PHP and integrated with MySQL or other server-side technologies. It is important to ensure that the server recognises the MIME type of the generated WML. However, despite this dynamic element, many useful WML sites were created before the language was overtaken by events.

Here are some pointers to the future with WAP.

• WML enforces strict XML compliance, making it a better language. HTML has never enforced this, resulting in variations in behaviour, especially when the syntax is 'relaxed'.
• A single server call delivers a number of 'cards', thus reducing the number of calls to the server. While the use of jQuery in an HTML page does not achieve the same result, it can reduce the number of server calls.
• Local validation of user input as is included in Bootstrap
• There is a direct link to phone calls and SMS messages to connect to the native features of the phone.

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