Wireless Application Protocol

Wireless Application Protocol (WAP) defines an open, universal standard for the delivery of the Internet and other value-added services to wireless networks and mobile communication devices such as mobile phones and personal digital assistants (PDAs). In general, WAP specifications encourage the creation of wireless devices that are compatible with each other, regardless of the manufacturer or service provider.

WAP is not a true protocol in the sense of the Internet Protocol (IP) or the Secure Sockets Layer (SSL); rather, it is a set of communication networking- and application-environment specifications that mirror functions similar to those performed by older, more common ones associated with the Internet, such as Hypertext Transfer Protocol (HTTP) and Transmission Control Protocol (TCP).

Compared to other specifications, WAP is a fairly recent development in information delivery. In 1997, the WAP forum (http://www.wapforum.org) was founded and organized with the goal of defining specifications for WAP. While original members Motorola, Nokia, and http://Phone.com (formerly Unwired Planet) had begun individually to define their own [Page 483]wireless data protocols, the WAP forum provided a cooperative opportunity to develop and share protocols for providing information to wireless communication devices. The result was a series of documents detailing the current standards that have been widely adopted by the industry. The WAP Forum has since grown from its modest size, and currently includes over 350 companies in its membership.

WAP recognizes that handheld wireless devices create a challenge not only for hardware and software designers but also for consumers. As a result, the protocols attempt to directly address constraints such as small display size, limited bandwidth and memory, and weak processing power that are typically associated with wireless devices. Two major considerations make WAP compliance attractive for potential wireless-device users. First, WAP-compliant devices allow these users to access and retrieve information from virtually anywhere, which complements many services offered by, for instance, mobile-telephone service providers. Second, WAP ensures “interoperatability” among compliant devices and network components, reducing potential software and architecture conflicts.

The foundation for WAP protocols has been and will continue to be the existing industry Internet standards, which WAP extends and leverages. As such, WAP includes familiar Internet-based tools such as browsers, URLs, and gateways. The current set of protocols defines key features, including: the WAP Programming Model, analogous to the World Wide Web Programming Model; Wireless Markup Language (WML) and WMLScript, a programming language analogous to HTML; a microbrowser, analogous to a Web browser; a complete protocol stack, designed to minimize the need for bandwidth as well as enable changes in one specification to occur independent of the others; and a Wireless Telephony Applications (WTA) framework for the development of advanced telephone features such as text messaging.

WAP is designed according to a “client server” approach, similar to that employed by the Internet. When someone requests information using a WAP microbrowser-enabled device, the request is processed by a WAP gateway, which translates it from WML to HTML and forwards it to a server. The request is then processed by the server, which returns a response; the response is sent to the WAP gateway, where the information is extracted, encoded into WML, and forwarded to the microbrowser, which decodes and shows the response.

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