CHAPTER 4

CHAPTER 4

WIRELESS APPLICATION

PROTOCOLPrepared By,

Prof.M.Dhanalakshmi,IT Dept,

SCET, Surat.

INTRODUCTION We are moving towards a net-centric world,

where Internet is becoming part of our environment.

Along with physical environment we also acquire information and knowledge from internet.

In 2G cellular network data access was possible over mobile phones using WAP over circuit.

In a circuit, the user pays for the circuit even during the idle period when there is no data transmission.

INTRODUCTION The data speed supported by CSD is in range of

9.6K bits per second. For internet access 9.6K bits per second is

unlikely to offer a good user experience. GPRS is designed to overcome some of these

constraints of GSM and offer higher data rate. GPRS allows for short bursty traffic such as

email and web browsing including large volumes of data.

GPRS has the ability to offer data speeds from 14.4 KBps to 171.2KBps.

Internet traffic is asymmetric in the sense that traffic volume from network to user agent is higher compared to traffic in reverse direction.

Wireless Application Protocol (WAP) is designed for access to internet and advanced telephony services from mobile phones.

WAP pays proper sensitivity to the constraints of these devices like small display, limited keys on the keypad, no pointer device like mouse etc..

Independent of their network, bearer and terminals user will b able to access internet and corporate internet services while mobile.

Net-net using WAP , a mobile user will be able to access same wealth of information from a pocket-sized device as they can from a desktop.

WAP WAP forum develops standards for

application deployment over wireless devices like PDAs and mobile phones.

WAP is based on layered architecture. WAP protocol stack is similar to OSI network

model. These layers consists of:

Wireless Application Environment Wireless Session Protocol Wireless Transaction Protocol Wireless Transport Layer Security. Wireless Datagram Protocol.

WAP

WIRELESS APPLICATION

ENVIRONMENT [WAE]

WAE The application environment of WAE comprises

multiple components to provide facilities like: User Agent: Browser or client program. Wireless Markup Language (WML): A

lightweight markup language similar to HTML but optimized for use in wireless devices.

WMLScript: Lightweight client side scripting language, similar to JavaScript in web.

Wireless Telephony Application: Telephony services and programming interfaces.

WAP Push Architecture: Mechanisms to allow origin servers to deliver content to the terminal without the terminal requesting for it.

Content Formats: Set of well defined data formats including images, phone book records and calendar information.

WAP APPLICATION ENVIRONMENT [WAE] Primary objective of WAE is to provide an

interoperable environment to build services in wireless space.

Covers system architecture related to user agents, networking schemes, content formats, programming languages and shared services based on WWW.

Content is transported using standard protocols in WWW domain and optimized HTTP like protocols in wireless domain.

WAE architecture allows all content and services to be hosted on standard web servers.

WAE

WAE A WAP request from the browser is routed

through a WAP gateway. The gateway acts as an intermediary

between the client and network through a wireless last mile.

Gateway does encoding and decoding of data transferred from and to the mobile agent.

Purpose of encoding is to minimize the size of data transacted over air.

Reduced data size reduces the computational power required by the client to process the data.

WAE Gateway processes the request, retrieves

contents from the server using Java Servlets, J2EE, CGI Scripts or some other dynamic mechanism.

The data is formatted as WML and returned to the client.

Client device employ logic through embedded WML Script for client side processing of WML.

Elements of WAE model includes: WAE User Agents Content Generators Standard Content Encoding Wireless Telephony Applications

WAE WAE User Agents:

User facing client software i.e browser. User agents are integrated into the WAE

architecture. They interpret network content referenced by a

URL. WAE includes user agents for two primary

standard contents: encoded WML and compiled WML script.

Content Generators: Applications on origin servers that extract

standard content in response to requests from user agents.

Content servers are typically HTTP servers used in WWW.

WAE Standard Content Encoding:

Set of well defined content encoding allowing user agent to navigate web content.

Standard content encoding includes compression encoding for WML, bytecode encoding for WMLScript, standard image formats.

Wireless Telephony Applications: A collection of telephony specific extensions for

call and telephony feature control.

USER AGENT User agent signifies an agent who works on

behalf of the user. In WWW and WAE context, user agent is the

user facing browser software. In WAE it is referred as micro-browser. WAE does not formally specify the

functionality of user agent. But only defines fundamental services and

formats that are needed to ensure interoperability among implementations and different layers.

A Wireless Telephony Application user agent has been specified as an extension to WAE specification for mobile telephony environments.

USER AGENT PROFILE [UAPROF] UAProf specification allows WAP to notify the

content server about the device compatibility. Also referred as Capability and Preference

Information. CPI is passed from WAP client to origin server

through intermediate network points. It is compatible with Composite

Compatibility/Preference Profile of W3C consortium.

CPI include hardware characteristics, software characteristics, application/user preferences, WAP characteristics.

Devices that support UAProf architecture provide a URL in the WAP or HTTP session header.

WIRELESS MARKUP LANGUAGE WML is a tag based document manipulation

language. WML is designed to specify presentation and

user interaction on mobile phones and other wireless devices.

These devices suffer from different constraints like small displays, limited user input facilities, narrow band network connection, limited network resources, limited memory resources, limited computational devices and absence of pointer device.

WIRELESS MARKUP LANGUAGE WML implements a deck and card metaphor. Deck-> Logical representation of a

document. Decks are made up of multiple cards. Each WML card , in a deck performs a

specific task for a particular user interaction. To access a document , a user navigates to a

card reviews its contents, makes a choice or enters information and then moves to another card.

WML decks can be stored in static files and fetched by CGI, JSP and ASP scripts.

Also dynamically generated by Java servlets running on origin server.