WAP (Wireless Application Protocol)
The Wireless Application Protocol (WAP) is a system designed to format and filter internet content for use in mobile devices. By linking the two 'hot-topics' in communication - the internet and mobile technology - WAP provides a very valuable service. Motorola, Nokia, Ericsson and Phone.com set up the WAP Forum in mid 1997 with a view to establishing this standard, which has been widely accepted by over 200 members of the Forum.
As a scalable standard, WAP is designed to work with any mobile handset network type. It will function with GSM (Global System for Mobile Communication), CDMA (Code Division Multiple Access) and PDC (Personal Digital Cellular). It will also be compatible with any data transmission service e.g. SMS (Short Message Service) or GPRS (General Packet Radio Service). Later versions of the standard have evolved to make use of the more advanced technologies available.
WAP incorporates a simple microbrowser, designed to work on the limited platforms of mobile handsets, with a central WAP gateway that performs the more processor-heavy operations. It defines a standard for data transmission to the handset, WDP (WAP datagram protocol), which is a variation of the internet standard transmission protocol, HTTP (Hypertext Transport Protocol), but redesigned for wireless network characteristics. WDP mostly differs from HTTP by stripping out much of the text information, replacing it with more efficient binary information for the low-bandwidth connection. The WAP data can be sent over any available network, be it the circuit-switched connection of TDMA (Time Division Multiple Access) IS-136 or packet-switched GPRS.
Added to this core transmission protocol are several scalable layers that can develop independently. The wireless transport layer security (WTLS) layer adds optional encryption facilities that enable secure transactions. WTP (WAP transaction protocol) adds transaction support, adding to the datagram service of WPD, while WSP (WAP session protocol) allows efficient data exchange between applications.
WAP also defines an application environment (WAE) that enables third-party developers to develop more advanced services and applications, along with the microbrowser used to access web pages on the handset itself.
To access internet content, the user's handset sends a request to the WAP gateway, which retrieves the information in either HTML (Hypertext Markup Language) or WML (Wireless Markup Language) from the host server. WML is a variation of HTML, designed specifically to enable viewing on the limited mobile terminal platform. If the information retrieved is in HTML, a filter in the gateway will attempt to convert it to WML. The information will then be transmitted to the handset over whatever network is available, using the transmission protocols described above.
In some cases, where HTML data is generated using a style sheet to convert XML data using an XSL processor, a WML style sheet can be added to the system to generate seamless information in the correct format for wireless viewing.
FUTURE OF WAP
Because WAP is a protocol designed to work over any mobile network, its use will continue to increase as more sophisticated data transmission technologies are introduced (e.g. GPRS, EDGE (Extended Data for Global Evolution) and W-CDMA (Wideband-CDMA)). As the bandwidth available to mobile terminals and the quality of displays improve, WAP can be enhanced to provide as effective an internet viewing experience as is possible on fixed terminals.