WIRELESS APPLICATION PROTOCOL

INTRODUCTION

u The name “Wireless Application Protocol” (WAP) is misleadng. WAP is not actually a protocol at all, in the sense that HTTP and IP are protocols. In fact, WAP involves multiple protocols and a complete network architecture for delivery of wireless content. In 1997, several companies  organized an industry group called the WAP Forum. This group produces the WAP specification, a (long and detailed) series of technical documents that define standards for implementing wireless network application.

u WAP specifies an architecture based o layers that follows OSI model fairly closely. The WAP model, or stack as it is commonly known, is illustrated below.

 

APPLICATION LAYER     

     WAP’s application layer is the wireless Application Environment (WAE). WAE directly supports WAP application development with Wireless Markup Language (WML) instead of JavaScript. WAE also includes the Wireless Telephony Application Interface (WTAI, or WTA for short) that provides a programming interface to telephones for initiating calls, sending text messages, and other networking capability.

 

SESSION LAYER

     WAP’s session layer is the Wireless Session Protocol (WSP). WSP is the equivalent to HTTP for WAP browsers. WAP involves browsers and servers just like the web, but HTTP was not a practical choice for WAP because of its relative inefficientcy on the wire. WSP conserves precious bandwidth on wireless links, in particular, WSP works with relatively compact binary data where HTTP works mainly with text data.

u Transaction, Security and Transport Layers

     These three protocols can be thought of as “glue layers” in WAP.

ØWireless Transaction Protocol (WTP)

ØWireless Transaction Layer Security (WTLS)

ØWireless Datagram Protocol (WDP)

 

GOALS OF WAP FORUM

The WAP Forum has the following goals:

u To bring internet content and advanced data services to Wireless phones and other wireless terminals.

u To create a global Wireless protocol specification that works across all wireless network technologies.

u To enable the creation of content and applications that scale across a wide range of wireless bearer networks and device types.

u To embrace and extend standards and technology wherever possible and appropriate.

u It is also very important for the WAP Forum’s specification in such a way that they complement existing standards. For example, the WAPV 1.0 specification is designed to sit on top of existing bearer channel standards so that any bearer standard can be used with the WAP protocols to implement complete product solutions. When the WAP Forum identifies a new area of technology where a standard does not exist, or exists but needs modification for wireless, it works to submit its specifications to other industry standard groups.

WAP PROTOCOL STACK

u  Any network is organized as a series of layers or levels where each level performs a specific function. The set of rules that governs the communication between the peer entities within a layer are called protocols. The layers and protocols together forms the Protocol Stack. The request from the mobile device is sent as a URL through the operators network to the WAP gateway, which is the interface between the operators network and the internet.

WAP: MAIN FEATURES

u Browser

–Micro browser, similar to existing web browser

u Markup Language

–Similar to HTML, adapted to mobile devices

u Script Language

–Similar to Javascript, adapted to mobile devices

u Gateway

–Transition from Wireless to wired world

u Server

–Wap/Origin Server, similar to existing web servers

u Protocol Layers

–Transport layer, security layer, session layer etc

u Telephony Application Interface

–Access to telephony functions

APPLICATIONS

u  The way in which mobile wireless  devices are used differs dramatically from the way we use PCs.

 

u On a PC we may spend hours constantly connected to the web hunting for information at work or playing complex, immersive games at home.

 

u On a wireless device, we tend to be away from home and “online” for relatively brief and unpredictable periods of time.

 

u The wireless industry hopes that WAP devices will become popular for ecommerce applications like online banking in the not so distant future.

CONCLUSION

          In responding to the backlash against WAP, advocates are quick to point out that WAP technology exists today in a very early, primitive form compared to how it will evolve.  WAP defines an alternative  to the web for content delivery networks. The WAP model was optimized for the following constraints, that are very different from the constraints found on today’s web.