lecture 12 - wireless application protocol

8/3/2019 Lecture 12 - Wireless Application Protocol

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Wireless ApplicationProtocol Architecture

Mobile Computer Technology

Joo Paulo PONCIANO

Faculty of Science and EngineeringFaculty of Science and Engineering

Department of Engineering and TechnologyDepartment of Engineering and Technology


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Unit Outline

WAP Motivation

WAP Requirements Architecture and Overview

Components of the WAP Architecture

Compliance and Interoperability


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BackgroundMotivation

WAP is positioned at the convergence of two rapidlyevolving network technologies, wireless data and theInternet.

Most of the technology developed for the Internet hasbeen designed for desktop and larger computers, andmedium-to-high bandwidth.

Wireless devices present a more constrainedcomputing environment.


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BackgroundMotivation - II

Mass-market handhelddevices and theirwireless networks tendto have: Less powerful CPUs

Less memory (ROM andRAM)

Restricted powerconsumption

Smaller displays Different input devices

(e.g., a phone keypad)

Wireless data networkspresent a constrainedcommunication

environment due to

limitations of power, available spectrum,

mobility,

Wireless data networks tend to have:Less bandwidth

More latency

Less connection stability

Less predictable availability


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BackgroundMotivation - III

Provisioning of value-added services withsolutions to be:

Interoperable

Scaleable

Efficient

Reliable

Secure

The WAP specifications adapt existing networktechnology to the special requirements ofhandheld wireless data devices.


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BackgroundRequirements

Leverage existing standards where possible

Define a layered, scaleable, and extensible

architecture

Support as many wireless networks as possible

Optimise for narrowband bearers with potentially highlatency and for efficient use of device resources (lowmemory/CPU usage/power consumption)

Provide support for secure applications and

communication.


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BackgroundRequirements - II

Enable the creation ofMan Machine Interfaces (MMIs)with maximum flexibility and vendor control

Provide access to local handset functionality, such as

logical indication for incoming call

Facilitate network-operator and third-party serviceprovisioning

Support multivendor interoperability by defining theoptional and mandatory components of the specifications

Provide a programming model for telephony services andintegration


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Architecture and OverviewThe WAP Model

Similar to the WWW programming model.

Optimizations and extensions have been made in order tomatch the characteristics of the wireless environment.

WAP content and applications are specified in a set of well-known content formats based on the familiar WWW contentformats.

Content is transported using a set ofstandardcommunication protocols based on the WWW.

A micro browserin the wireless terminal coordinates theuser interface and is analogous to a standard Web browser.


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Architecture and OverviewThe WAP Model - II

WAP defines a set of standard components

that enable communication between mobileterminals and network servers, including:

Standard naming model.

Content typing.

Standard content formats.

Standard communication protocols.


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Architecture and OverviewThe WAP Model - IV

This infrastructure ensures that mobile terminal userscan browse a wide variety of WAP content andapplications, and that the application author is able tobuild content services and applications that run on a

large base of mobile terminals.

The WAP proxy allows content and applications to behosted on standard WWW servers and to bedeveloped using proven WWW technologies such as

CGI scripting.

While the nominal use of WAP will include: a Web server,

WAP proxy WAP client,


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WAP Gateway

WML Encoder

WMLScript

Compiler

Protocol Adapters

Client

WML

WML-

Script

WTAI

Etc.

Web Server

Content

CGI

Scripts

etc.

WMLDecks

withWML-Script

Architecture and OverviewThe WAP Programming Model

WSP/WTP HTTP

Encoders/

Decoders

WAE user

agent Origin Server

Encoded

request

Encodedresponse

RequestResponse

Request


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HTMLFilter

WebServer

Architecture and OverviewExample WAP Network

WirelessNetwork

WTA

Server

WAPProxy

WML

HTMLWML

BinaryWML


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Architecture and OverviewThe WAP Security Model

WAP enables a flexible security infrastructure thatfocuses on providing connection security between aWAP client and server.

WAP can provide end-to-end security between WAPprotocol endpoints. If a browser and origin serverdesire end-to-end security, they must communicatedirectly using the WAP protocols.

End-to-end security may also be achieved if the WAPproxy is trusted or, for example, located at the samephysically secure place as the origin server.


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WAP Protocol ArchitectureWireless Application Environment

WAE is a general-purpose application environmentbased on a combination of WWW and mobiletelephony technologies.

WAE is to establish an interoperable environmentthat will allow operators and service providers to buildapplications and services for wireless platforms.

WAE includes a micro-browser environmentcontaining the following functionality: Wireless Markup Language (WML).

WMLScript.

Wireless Telephony Application (WTA, WTAI). Telephony

services and programming interfaces. Content formats.


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WAP Protocol ArchitectureWireless Session Protocol

WSP provides the application layer of WAPwith a consistent interface for two session

services. Connection-oriented service that operates above

the transaction layer protocol WTP.

Connectionless service that operates above a

secure or nonsecure datagram service (WDP).

WSP consist of services suited for browsingapplications (WSP/B).


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WAP Protocol ArchitectureWireless Session Protocol - II

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 common facility forreliable and unreliable data push

Protocol feature negotiation

The protocols in the WSP family are optimized forlow-bandwidth bearer networks with relatively longlatency. WSP/B is designed to allow a WAP proxy toconnect a WSP/B client to a standard HTTP server.


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WAP Protocol ArchitectureWireless Transaction Protocol

WTP runs on top of a datagram service and providesa lightweight transaction-oriented protocol that issuitable for implementation in thin clients.

WTP operates oversecure or nonsecure wirelessdatagram networks and provides the following: Three classes of transaction service:

Unreliable one-way requests

Reliable one-way requests

Reliable two-way request-reply transactions WTP provides and acknowledged service (user-to-user

reliability)

Optional out-of-band data on acknowledgments

PDU concatenation and delayed acknowledgment to reducethe number of messages sent

Asynchronous transactions


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WAP Protocol ArchitectureWireless Transport Layer Security

WTLS is a security protocol based upontransport layer security (TLS) protocol. (used

by http)

WTLS is narrowband optimised and intendedfor use with the WAP transport protocols.

WTLS may also be used forauthentication ofelectronic business card exchange.


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WAP Protocol Architecture

Wireless Application Environment

Wireless Session Protocol

Wireless Transaction Protocol

Wireless Transport Layer Security

Wireless Datagram Protocol

Bearers

GPRS GSM CDMA PHS CDPD PDC-P IDEN FLEX

OtherServices

andApplications


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WAP Protocol ArchitectureWireless Transport Layer Security II

Applications are able to enable or disable

WTLS features.

WTLS provides the following features:

Data integrity.

Privacy. Authentication.

Denial-of-service protection.


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WAP Protocol ArchitectureWireless Datagram Protocol

Security, Session, and Application layers are able tofunction independently of the underlying wireless network.This is done by adapting the Transport layer to specificfeatures of the underlying bearer via the WDP

WDP is replaced by UDP when used over an IPnetwork layer.

Provide consistent interface to a fundamental transport

service across all wireless bearer networks.

Provides a connectionless, unreliable datagramservice.


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WAP Protocol ArchitectureBearer Services

The WAP protocols are designed for Different Typesof Bearer Services:

Short message, (SMS)

Packet Switched Data, Circuit Switched Data.

Responsible for different levels of:

Quality of service

Throughput

Delay

Error Rate

The list of supported bearers will change over time,with new bearers being added as the wireless market

evolves.


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Other Services and Applications

The WAP layered architecture enables other servicesand applications to utilize the features of the WAPstack through a set of well-defined interfaces.

External applications may access the Session,Transaction, Security, and Transport layers directly.

For example, applications (e.g., electronic mail,calendar, phone book, notepad, and electroniccommerce) or services (e.g., white and yellow pages)may be developed to use the WAP protocols.


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Sample WAP Configurations


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Compliance and

Interoperability

To this end the WAP Forum has created a WAP

Conformance Specification [WAPConf] and is working

to maintain current information relating to all issues of

WAP interoperability.

Interoperability achieved by testing:

Static testing is a manufacturers statement of the capabilities

and functions of a product.

Dynamic testing is the real form of testing that leads to a highdegree of confidence that two products will successfully

interoperate.


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Recommended Reading

Inside WAP: Programming Applicationswith WML and WMLScript

Esko Hannula

Adison Wesley - ISBN: 0-201-72591-6

Chapter 1.1

Chapter 1.2

lecture 12 - wireless application protocol

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