Wireless Application Protocol

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Wireless Application Protocol (WAP) is a technical standard for accessing information over a mobile wireless network. A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol.

Before the introduction of WAP, mobile service providers had limited opportunities to offer interactive data services, but needed interactivity to support Internet and web applications such as:

  • Email by mobile phone
  • Tracking of stock-market prices
  • Sports results
  • News headlines
  • Music downloads

The Japanese i-mode system offers another major competing wireless data protocol.

  • WAP supports most wireless networks. These include CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT, DataTAC, and Mobitex.
  • WAP is supported by all operating systems. Ones specifically engineered for handheld devices include PalmOS, EPOC, Windows CE, FLEXOS, OS/9, and JavaOS.

WAP is supported by all operating systems. Ones specifically engineered for handheld devices include PalmOS, EPOC, Windows CE, FLEXOS, OS/9, and JavaOS.

WML language

WAP is not a language and therefore is not comparable to HTML, however, most WAP implementations use the language WML. Although WAP supports HTML and XML, the WML language (an XML application) is specifically devised for small screens and one-hand navigation without a keyboard. WML is scalable from two-line text displays up through graphic screens found on items such as smart phones and communicators. WAP also supports WMLScript. It is similar to JavaScript, but makes minimal demands on memory and CPU power because it does not contain many of the unnecessary functions found in other scripting languages.

WAP and WML lack good standards specifications, so there are variances across the industry. Certain WML web pages may render best under specific manufacturers phones, which site to which phone varies.

Technical specifications

The WAP standard described a protocol suite allowing the interoperability of WAP equipment, and software with different network technologies, such as GSM and IS-95 (also known as CDMA).

Wireless Application Environment (WAE) WAP protocol suite
Wireless Session Protocol (WSP)
Wireless Transaction Protocol (WTP)
Wireless Transport Layer Security (WTLS)
Wireless Datagram Protocol (WDP)
*** Any Wireless Data Network ***

The bottom-most protocol in the suite, the WAP Datagram Protocol (WDP), functions as an adaptation layer that makes every data network look a bit like User Datagram Protocol (UDP) to the upper layers by providing unreliable transport of data with two 16-bit port numbers (origin and destination). All the upper layers view WDP as one and the same protocol, which has several "technical realizations" on top of other "data bearers" such as SMS, USSD, etc. On native IP bearers such as GPRS, UMTS packet-radio service, or Point-to-Point Protocol (PPP) on top of a circuit-switched data connection, WDP is in fact exactly UDP.

Wireless Transport Layer Security (WTLS), an optional layer, provides a public-key cryptography-based security mechanism similar to TLS.

Wireless transaction protocol (WTP) provides transaction support (reliable request/response) adapted to the wireless world. WTP supports more effectively than Transmission Control Protocol (TCP) the problem of packet loss, which occurs commonly in 2G wireless technologies in most radio conditions, but is misinterpreted by TCP as network congestion.

Finally, one can think of WSP initially as a compressed version of HTTP.

This protocol suite allows a terminal to transmit requests that have an HTTP or HTTPS equivalent to a WAP gateway; the gateway translates requests into plain HTTP.

Wireless Application Environment (WAE)

The WAE space defines application-specific markup languages.

For WAP version 1.X, the primary language of the WAE is Wireless Markup Language (WML). In WAP 2.0, the primary markup language is XHTML Mobile Profile.

WAP 2.0

A re-engineered 2.0 version was released in 2002. It uses a cut-down version of XHTML with end-to-end HTTP, dropping the gateway and custom protocol suite used to communicate with it. A WAP gateway can be used in conjunction with WAP 2.0; however, in this scenario, it is used as a standard proxy server. The WAP gateway's role would then shift from one of translation to adding additional information to each request. This would be configured by the operator and could include telephone numbers, location, billing information, and handset information.

Mobile devices process XHTML Mobile Profile (XHTML MP), the markup language defined in WAP 2.0. It is a subset of XHTML and a superset of XHTML Basic. A version of cascading style sheets (CSS) called WAP CSS is supported by XHTML MP.

Commercial status

The adoption of WAP in the United States suffered because many cell phone providers required separate activation and additional fees for data support, and also because telecommunications companies have sought to limit data access to only approved data providers operating under license of the signal carrier.

In recognition of the problem, the FCC issued an order on 31 July 2007 which mandated that licensees of the 22-megahertz wide "Upper 700 MHz C Block" spectrum will have to implement a wireless platform which allows customers, device manufacturers, third-party application developers, and others to use any device or application of their choice when operating on this particular licensed network band.

Spin-off technologies

Spin-off technologies, such as Multimedia Messaging Service (MMS), a combination of WAP and SMS, have further driven the protocol. An enhanced appreciation of device diversity, supported by the concomitant changes to WAP content to become more device-specific rather aiming at a lowest common denominator, allowed for more usable and compelling content. As a result, the adoption rate of WAP technology is rising.





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