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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 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.
- Spring '14