WAP Model

Wireless Application Protocol or WAP is an open international standard for applications that use wireless communication. Its principal application is to enable access to the internet from a mobile phone or PDA.

The WAP Model

The WAP programming model (Figure) is similar to the WWW programming model. This provides several benefits to the application developer community, including a familiar programming model, a proven architecture, and the ability to leverage existing tools (eg, Web servers, XML tools, etc.). Optimisations and extensions have been made in order to match the characteristics of the wireless environment. Wherever possible, existing standards have been adopted or have been used as the starting point for the WAP technology.


WAP content and applications are specified in a set of well-known content formats based on the familiar WWW content formats. Content is transported using a set of standard communication protocols based on the WWW communication protocols. A micro browser in the wireless terminal co-ordinates the user interface and is analogous to a standard web browser.

WAP defines a set of standard components that enable communication between mobile terminals and network servers, including:

• Standard naming model: WW-standard URLs are used to identify WAP content on origin servers.
• Content typing: All WAP content is given a specific type consistent with WWW typing. This allows WAP user agents to correctly process the content based on its type.
• Standard content formats: WAP content formats are based on WWW technology and include display markup, calendar information, electronic business card objects, images and scripting language.
• Standard communication protocols: WAP communication protocols enable the communication of browser requests from the mobile terminal to the network web server.The WAP content types and protocols have been optimised for mass market, hand-held wireless devices. WAP utilises proxy technology to connect between the wireless domain and the WWW.

The WAP proxy typically is comprised of the following functionality:

• Protocol Gateway: The protocol gateway translates requests from the WAP protocol stack (WSP, WTP, WTLS, and WDP) to the WWW protocol stack (HTTP and TCP/IP).
• Content Encoders and Decoders – The content encoders translate WAP content into compact encoded formats to reduce the size of data over the network. This infrastructure ensures that mobile terminal users can browse a wide variety of WAP content and applications, and that the application author is able to build content services and applications that run on a large base of mobile terminals. The WAP proxy allows content and applications to be hosted on standard WWW servers and to be developed using proven WWW technologies such as CGI scripting. While the nominal use of WAP will include a web server, WAP proxy and WAP client, the WAP architecture can quite easily support other configurations. It is possible to create an origin server that includes the WAP proxy functionality. Such a server might be used to facilitate end-to-end security solutions, or applications that require better access control or a guarantee of responsiveness, eg, WTA.

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