Page 180 - DCAP512_WAP_AND_WML

WAP & WML

Notes  Reliable two-way request-reply transactions
 Optional user-to-user reliability: WTP user triggers the confirmation of each received message
 Optional out-of-bound data on acknowledgements
 PDU concatenation and delayed acknowledgements to reduce the number of message sent

 Asynchronous transactions

Did u know? What are the functions of Wireless Transmission Protocol?
The Wireless Transmission Protocol (WTP) aids reliable transaction management and
data exchange with the upper layers of the WAP layers. The “transaction” in this context is
the unique pairing of device client requests with content server response.
This protocol monitors message status and resends messages as necessary. This reliable message
exchange is accomplished by sending acknowledgement messages for data. If the message is not
acknowledged within “x” period, the message is resent until acknowledged. WTP also prompts
the mobile user to confirm receipt of data.
WSP

The WAP Session Protocol (WSP) layer provides a lightweight session layer to allow efficient
exchange of data between applications.
The Wireless Session Protocol (WSP) offers the application layer of WAP with a consistent
interface for two session services.
 The first is a connection oriented service that operates above the transaction layer protocol
WTP

 The second is a connectionless service that operates above a secure or non-secure datagram
service (WDP)
The Wireless Session Protocol currently consists of services suited for browsing applications
(WSP/B). WSP/B provides the following functionality:
 HTTP/1.1 functionality and semantics in a compact over-the-air encoding

 Long-lived session state
 Session suspend and resume with session migration
 A facility for reliable and unreliable data push

 Protocol feature negotiation
The protocol in the WSP family is optimized for low-bandwidth with relatively long latency.
WSP/B is modeled to permit a WAP proxy to connect a WSP/B client to standard HTTP server.
The Wireless Session Protocol (WSP) manages the exchange of interaction between the mobile
devices and the WAP Gateway, as well as the sessions between the two devices. WSP supports
the operation of the micro browser on the mobile device.
WSP includes HTTP 1.1 semantics. This eases the two-way transaction between the WAP Gateway
and Web Server.

The WAP Gateway translates WSP requests from the mobile device and sends them to a Web
Server. In the return of data from the Web Server, the WAP gateway translates the Web Server’s
HTTP data into WSP format before sending it forward to the mobile device. The WAP session

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