Wireless layer wireless and mobile provides a

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Unformatted text preview: s is certainly not feasible. To address these issues, researchers started working towards the development of a technology that could allow development of applications that are independent of the underlying wireless access technology and that could also enable access of information from existing web sites using mobile devices. The result of this was WAP. WAP specifications have been developed by the WAP Forum, a consortium of leading wireless companies. It supports interoperability of different wireless networks, devices and applications using a common set of application and network protocols. In fact, WAP is a stack of protocols that defines the type and structure of messages that two devices have to use when they are communicating with each other in a wireless environment. The WAP protocol stack contains a set of six layers, which are application layer, session layer, transaction layer, security layer, transport layer, and wireless layer. Figure 17.26 presents a summary of the various WAP layers, the protocols at each layer, and their functions. WAP protocols have been designed to reduce the problems associated with the use of the Internet protocols for wireless data transfer. They do this simply by eliminating unnecessary data transfers and using binary code to reduce the amount of data that has to be sent. For instance, WAP has introduced a new Markup Language called the Wireless Markup Language (WML), which is a version of HTML optimized for mobile devices. Figure 17.27 shows the basic architecture of WAP. The architecture is similar to web architecture, but it requires a WAP gateway for translating between HTTP and WAP. That is, the WAP gateway acts as a proxy server to a mobile client and translates requests from WAP protocol stacks to protocol stacks employed by the information server on the other side. The WAP gateway has encoders to translate the content coming from the server into compact formats to reduce the size of data over the wireless network. The WAP gateway usually resides in the organization that provides carrier services to its subscribers. This ensures that mobile users c...
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This document was uploaded on 04/07/2014.

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