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WAP has two meanings. The first, older, meaning is Wireless Application Protocol. WAP is a newer protocol in the TCP/IP suite. At first look, it appears that existing protocols such as HTTP and TCP fill the need. These protocols were designed with the idea, that a device has continuous connection and can send multiple requests for data. Wireless devices have considerable constrains regarding power, processing and display parameters.
Other considerations such as signal fade, long latently times, security and low bandwidth all contributed to the need to release WAP.
WAP addresses these issues in creative ways. Instead of uncompressed text strings, data is sent in compressed binary packets. Hyper Text Markup Language (HTML) is replaced with the Wireless Markup Language (WML), based on the Extensible Markup Language (XML) format. This allows data to be optimized for smaller displays found in hand-held devices such as Web enabled Personal Communication System (PCS) phones and Personal Digital Assistants (PDA) such as the Palm Pilot and Hand Spring units.
WAP differs from other offerings by using UDP instead of TCP for lower overhead, in combination with the new Wireless Transaction Protocol (WTP) on the transport layer. A feature of WTP is a small session re-establishment protocol that allows a transmission to continue from the drop point without the overhead of the initial session.
WAP overcomes the limitations of being UDP based by the WAP Gateway. This service acts as a proxy server between the wireless device and the wired Internet. By eliminating the need for multiple routes, considerable overhead required for TCP is removed. Part of the functionality of the WAP Gateway is to act as a translator between the connection-oriented TCP protocol and WAPs connectionless UDP protocol.
A second meaning for WAP is Wired Access Point. This is the junction between 802.11 a/b/g wireless data traffic and the wired network. In fact 802.11 uses WAP with the Wireless Markup Language to communicate with the Wired Access Point.
In some countries, WAP/Web enabled PDA and PCS devices are very popular.
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