Wireless Transaction Protocol(WTP)

By Pathfinders

WHAT IS WAP?

Wireless Application Protocol

Standard created by wireless and Internet companies

Enables internet access from a cellular phone

Enables applications to scale across variety of transport options and device types

Protocol Stack for WAP

Other ServicesAnd

Applications

Transport Layer (WDP)

Security Layer (WTLS)

Transaction Layer (WTP)

Session Layer (WSP)

Application Layer (WAE)

SMS USSD CSD IS-136 CDMA CDPD PDC-P Etc

WAP Architecture

Web Server

Content

CGIScripts

etc.

WM

L D

ecks

wit

h W

ML

-Scr

ipt

WAP Gateway

WML Encoder

WMLScriptCompiler

Protocol Adapters

Client

WML

WML-Script

WTAI

Etc.

HTTPWSP/WTP

WHAT IS WTP?

Light weight transaction oriented protocol

Runs on top of datagram service

Chops data packets into lower level datagram's

Concatenates received datagram's into useful data

Operates above WDP to provide simple protocol suitable for low bandwidth mobile station

How it is designed for Wireless Environment

no explicit connection setup or tear down

optimized setup (data carried in first packet of protocol exchange)

seeks to reduce 3-way handshake on initial request

supports User acknowledgement or Stack acknowledgement option [acks may be forced from the WTP user (upper layer) default is stack ack]

WTP Transaction Services

WTP offers 3 classes of transactions services:

•Unreliable one-way request (Class 0)

•Reliable one-way request (Class 1)

•Reliable two-way request/response (Class 2)

TR-Invoke/Request

Operation of Class 0

Initiator Responder

TR-Invoke/ Indication

Invoke PDU(TID=N, TG, C=0,…)

TR-Invoke/Confirm

TR-Invoke/Request

Basic Operation of Class 1

Initiator Responder

TR-Invoke/ Indication

Invoke PDU(TID=N, TG, C=1,…)

Ack PDU(TID=N*)

TR-Invoke/Request

TR-Invoke/Confirm

Class 1 – with ‘User’ Acknowledgement

Initiator Responder

TR-Invoke/ Indication

Invoke PDU(TID=N, TG, C=1,…)

Ack PDU(TID=N*) TR-Invoke/

Response

Basic Operation of Class 2

Initiator Responder

TR-Invoke/Request

TR-Invoke/ Indication

Invoke PDU(TID=N, TG, C=2,…)

Result PDU

TR-Invoke/Confirm

TR-Invoke/Request

TR-Result/Indication

TR-Result/Response

Ack PDU

TR-Result/Confirm

Class 2 - with ‘Hold On’ Acknowledgement

Initiator Responder

TR-Invoke/Request

TR-Invoke/ Indication

Invoke PDU(TID=N, TG, C=2,…)

TR-Invoke/Confirm

TR-Result/Indication

TR-Result/Response

Ack PDU

TR-Result/Confirm

TR-Invoke/Request

Result PDU

Ack PDU

Class 2 - with ‘User’ Acknowledgement

Initiator Responder

TR-Invoke/Request

TR-Invoke/ Indication

Invoke PDU(TID=N, TG, C=2,…)

TR-Invoke/Confirm

TR-Result/Indication

TR-Result/Response

Ack PDU

TR-Result/Confirm

TR-Invoke/Request

Result PDU

Ack PDU TR-Invoke/Response

WTP Management Entity

Interface between WTP layer and environment of device

Monitors the state of mobile environment

Deals with all the issues related to Initialization Configuration Resources

as they pertain to WTP layer

WTP Features

Provides reliable, efficient data transfer based on request/reply paradigm

Supports selective re-transmission

Message oriented (not stream)

Supports Abort function

Supports concatenation of PDUs

Mobile WWW

References and Resources

Books- Understanding WAP

Official Website (specifications)

- www.wapforum.org

Thank You