wap tech seminar

8/2/2019 Wap Tech Seminar

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BACKGROUND

WAP is positioned at the convergence of two rapidly evolving network technologies,

wireless data and the Internet. Both the wireless data market and the Internet are

growing very quickly and are continuously reaching new customers. The explosive

growth of the Internet has fuelled the creation of new and exciting information

services. Most of the technology developed for the Internet has been designed for

desktop and larger computers and medium to high bandwidth, generally reliable data

networks. Mass-market, hand-held wireless devices present a more constrained

computing environment compared to desktop computers. Because of fundamental

limitations of power and form-factor, mass-market handheld devices tend to have:

Less powerful CPUs, Less memory (ROM and RAM), Restricted power consumption, Smaller displays, and Different input devices (eg, a phone keypad).

Similarly, wireless data networks present a more constrained communication

environment compared to wired networks. Because of fundamental limitations of

power, available spectrum, and mobility, wireless data networks tend to have:

Less bandwidth, More latency, Less connection stability, and Less predictable availability.


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Mobile networks are growing in complexity and the cost of all aspects for

provisioning of more value added services is increasing. In order to meet the

requirements of mobile network operators, solutions must be:

Interoperable terminals from different manufacturers communicate withservices in the mobile network;

Scaleable mobile network operators are able to scale services to customerneeds;

Efficient provides quality of service suited to the behavior andcharacteristics of the mobile network;

Reliable provides a consistent and predictable platform for deployingservices; and

Secure enables services to be extended over potentially unprotected mobilenetworks while still preserving the integrity of user data; protects the devices

and services from security problems such as denial of service.

Many of the current mobile networks include advanced services that can be offered to

end-users. Mobile network operators strive to provide advanced services in a useable

and attractive way in order to promote increased usage of the mobile network services

and to decrease the turnover rate of subscribers. Standard features, like call control,

can be enhanced by using WAP technology to provide customized user interfaces.

For example, services such as call forwarding may provide a user interface that

prompts the user to make a choice between accepting a call, forwarding to another

person, forwarding it to voice mail, etc. The WAP specifications address mobile

network characteristics and operator needs by adapting existing network technology

to the special requirements of mass-market, hand-held wireless data devices and by

introducing new technology where appropriate.


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THE BASIC PRINCIPLES OF WAP

A complete wireless Internet solution must use:

Existing standards: WAP runs in all networks including IP networks and with W3C

on HTTP NG.

Provide air interface independence: This principle allows the largest number of

service providers, software developers and handset manufacturers to benefit from one

unified specification. Service providers can implement a common solution across

their own disparate networks so that every subscriber has the best possible user

experience on each network.


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Provide device independence: Device independence offers similar benefits to bearer

independence. applications developed for one standard can operate on a wide variety

of devices that implement the specification; network operators gain a consistent user

interface for their services across multiple vendors' handsets; application developers

do not have to write separate versions of their code for different devices; and service

providers can choose any standard compliant device that meets their own

unique market requirements.

WHY TO CHOOSE WAP?

In the past, wireless Internet access has been limited by the capabilities of handheld

devices and

wireless networks. WAP utilizes Internet standards such as XML, user datagram

protocol (UDP), and IP. Many of the protocols are based on Internet standards such as


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hypertext transfer protocol (HTTP) and TLS but have been optimized for the unique

constraints of the wireless environment: low bandwidth, high latency, and less

connection stability. Internet standards such as hypertext markup language (HTML),

HTTP, TLS and transmission control protocol (TCP) are inefficient over mobile

networks, requiring large amounts of mainly text-based data to be sent. Standard

HTML content cannot be effectively displayed on the small-size screens of

pocketsized mobile phones and pagers. WAP utilizes binary transmission for greater

compression of data and is optimized for long latency and low bandwidth. WAP

sessions cope with intermittent coverage and can operate over a wide variety of

wireless transports.

WML and wireless markup language script (WML Script) are used to produce WAP

content. They make optimum use of small displays, and navigation may be performed

with one hand. WAP content is scalable from a two-line text display on a basic device

to a full graphic screen on the latest smart phones and communicators. The

lightweight WAP protocol stack is designed to minimize the required bandwidth and

maximize the number of wireless network types that can deliver WAP content.

Multiple networks will be targeted, with the additional aim of targeting multiple

networks. These include global system for mobile, communications (GSM) 900,

1,800, and 1,900 MHz; interim standard (IS)136; digital European cordless

communication (DECT); time-division multiple access (TDMA), personal

communications service (PCS), FLEX, and code division multiple access (CDMA).

All network technologies and bearers will also be supported, including short message

service (SMS), USSD, circuit-switched cellular data (CSD), cellular digital packet

data (CDPD), and GPRS. As WAP is based on a scalable layered architecture, each

layer can develop independently of the others. This makes it possible to introduce new

bearers or to use new transport protocols without major changes in the other layers.


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DEFINITIONS AND ABBREVIATIONS

Authoran author is a person or program that writes or generates WML, WMLScript

or other content.

Clienta device (or application) that initiates a request for a connection with a server.

Content subject matter (data) stored or generated at an origin server. Content is

typically displayed or interpreted by a user agent in response to a user request.Content Encoding when used as a verb, content encoding indicates the act of

converting content from one format to another. Typically the resulting format requires

less physical space than the original is easier to process or store and/or is encrypted.

When used as a noun, content encoding specifies a particular format or encoding

Standard or process.

Content Formatactual representation of content.

Device a network entity that is capable of sending and receiving packets of

information and has a unique device Address. A device can act as both a client and a

server within a given context or across multiple contexts. For example, a device can

service a number of clients (as a server) while being a client to another server.

JavaScripta de facto standard language that can be used to add dynamic behavior to

HTML documents. JavaScript is one of the originating technologies of ECMAScript.

Man-Machine Interfacea synonym for user interface.

Origin Serverthe server on which a given resource resides or is to be created. Often

referred to as a web server or an HTTP server.

Resource a network data object or service that can be identified by a URL.

Resources may be available in multiple representations (eg, multiple languages, data

formats, size and resolutions) or vary in other ways.

Server a device (or application) that passively waits for connection requests from

one or more clients. A server may accept or reject a connection request from a client.


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Terminal a device providing the user with user agent capabilities, including the

ability to request and receive information. Also called a mobile terminal or mobile

station.

Usera user is a person who interacts with a user agent to view, hear, or otherwise

use a resource.

User Agent a user agent is any software or device that interprets WML,

WMLScript, WTAI or other resources.This may include textual browsers, voice

browsers, search engines, etc.

WMLScripta scripting language used to program the mobile device. WMLScript is

an extended subset of the JavaScript

Abbreviations:-

For the purposes of this specification, the following abbreviations apply.

HTML HyperText Markup Language

HTTP HyperText Transfer Protocol

PDA Personal Digital Assistant

PICS Protocol Implementation Conformance Statement

RFC Request For Comments

SSL Secure Sockets Layer

TLS Transport Layer Security

URL Uniform Resource Locator [RFC1738]

W3C World Wide Web Consortium

WAE Wireless Application Environment [WAE]

WAP Wireless Application Protocol [WAP]

WDP Wireless Datagram Protocol [WDP]

WML Wireless Markup Language [WML]

WSP Wireless Session Protocol [WSP]

WTA Wireless Telephony Application [WTA]

WTLS Wireless Transport Layer Security [WTLS]

WTP Wireless Transaction Protocol [WTP]

WWW World-Wide Web


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ARCHITECTURE OVERVIEW

The World-Wide Web Model

The Internet World-Wide Web (WWW) architecture provides a very flexible and

powerful programming model (Figure 1). Applications and content are presented in

standard data formats, and are browsedby applications known as web browsers. The

web browser is a networked application, i.e., it sends requests for named data objects

to a network server and the network server responds with the data encoded using the

standard formats.


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The WWW protocols define three classes of servers:

The server on which a given resource (content) resides or is to be

created.

An intermediary program that acts as both a server and a client for the

purpose of making requests on behalf of other clients. The proxy typically resides

between clients and servers that have no means of direct communication, e.g. across a

firewall.

A server which acts as an intermediary for some other server. it receives

requests as if it were the origin server for the requested resource. The requesting client

may not be aware that it is communicating with a gateway.

The WAP Model


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The WAP programming model (Figure 2) is similar to the WWW programming

model. This provides several benefits to the application developer community,

including a familiar programming model, a proven architecture, and the ability to

leverage existing tools (e.g., Web servers, XML tools, etc.). Optimizations and

extensions have been made in order to match the characteristics of the wireless

environment. Wherever possible, existing standards have been adopted or have been

used as the starting point for the WAP technology.

WAP content and applications are specified in a set of well-known content formats

based on the familiar WWW content formats. A micro browser in the wireless

terminal co-ordinates the users interface and are analogous to a standard web browser.

The WAP content types and protocols have been optimized for mass market, hand-

held wireless devices. WAP utilizes proxy technology to connect between the wireless

domain and the WWW. The WAP proxy typically is comprised of the following

functionality:

The protocol gateway translates requests from the WAP

protocol stack (WSP, WTP, WTLS, and WDP) to the WWW protocol stack (HTTP

and TCP/IP).

The content encoders translate WAP content

into compact encoded formats to reduce the size of data over the network.


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COMPONENTS OF THE WAP ARCHITECTURE

The WAP architecture provides a scaleable and extensible environment for

application development for mobile communication devices. This is achieved through

a layered design of the entire protocol stack (Figure 4). Each of the layers of the

architecture is accessible by the layers above, as well as by other services and

applications.

The WAP layered architecture enables other services and applications to utilize the

features of the WAP stack through a set of well-defined interfaces. External

applications may access the session, transaction, security and transport layers directly.

The following sections provide a description of the various elements of the protocol

stack architecture.


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Wireless Application Environment (WAE)

The Wireless Application Environment (WAE) is a general-purpose application

environment based on a combination of World Wide Web (WWW) and Mobile

Telephony technologies. The primary objective of the WAE effort is to establish an

interoperable environment that will allow operators and service providers to build

applications and services that can reach a wide variety of different wireless platforms

in an efficient and useful manner. WAE includes a micro-browser environmentcontaining the following functionality:

Wireless Markup Language (WML)a lightweight markup language, similarto HTML, but optimized for use in hand-held mobile terminals;

WMLScripta lightweight scripting language, similar to JavaScript; Wireless Telephony Application (WTA, WTAI) telephony services and

programming interfaces

Content Formatsa set of well-defined data formats, including images, phonebook records and calendar information.

Wireless Session Protocol (WSP)

The Wireless Session Protocol (WSP) provides 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 connectionlessservice that operates above a secure or non-secure datagram service (WDP).The


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Wireless Session Protocols currently consist of services suited for browsing

applications (WSP/B). WSP/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 for reliable and unreliable data push, and Protocol feature negotiation.

Wireless Transaction Protocol (WTP)

The Wireless Transaction Protocol (WTP) runs on top of a datagram service andprovides as a light-weight transaction-oriented protocol that is suitable for

implementation in thin clients (mobile stations). WTP operates efficiently over

secure or non-secure wireless datagram networks and provides the following features:

Three classes of transaction service: Unreliable one-way requests, Reliable one-way requests, and

Reliable two-way request-reply transactions; Optional user-to-user reliability - WTP user triggers the confirmation of each

received message.

Wireless Transport Layer Security (WTLS)

WTLS is a security protocol based upon the industry-standard Transport Layer

Security (TLS) protocol, formerly known as Secure Sockets Layer (SSL). WTLS isintended for use with the WAP transport protocols and has been optimised for use

over narrow-band communication channels. WTLS provides the following features:

Data integrityWTLS contains facilities to ensure that data sent between theterminal and an application server is unchanged and uncorrupted.

PrivacyWTLS contains facilities to ensure that data transmitted between theterminal and an application server is private and cannot be understood by any

intermediate parties that may have intercepted the data stream.


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AuthenticationWTLS contains facilities to establish the authenticity of theterminal and application server.

Denial-of-service protection WTLS contains facilities for detecting andrejecting data that is replayed or not successfully verified. WTLS makes manytypical denial-of-service attacks harder to accomplish and protects the upper

protocol layers.

WTLS may also be used for secure communication between terminals, eg, for

authentication of electronic business card exchange. Applications are able to

selectively enable or disable WTLS features depending on their security requirements

and the characteristics of the underlying network (eg, privacy may be disabled on

networks already providing this service at a lower layer).

Wireless Datagram Protocol (WDP)

The Transport layer protocol in the WAP architecture is referred to as the Wireless

Datagram Protocol (WDP). The WDP layer operates above the data capable bearer

services supported by the various network types. As a general transport service, WDP

offers a consistent service to the upper layer protocols of WAP and communicate

transparently over one of the available bearer services. Since the WDP protocols

provide a common interface to the upper layer protocols the Security, Session and

Application layers are able to function independently of the underlying wireless

network. This is accomplished by adapting the transport layer to specific features of

the underlying bearer. By keeping the transport layer interface and the basic features

consistent, global interoperability can be achieved using mediating gateways.

WAP PROTOCOL STACK

WAP has a layered architecture as shown in the diagram below:

Wireless Application Environment (WAE)

Wireless Session Protocol (WSP)


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Wireless Transaction Protocol (WTP)

Wireless Transport Layer Security (WTLS)

Wireless Datagram Protocol (WDP)

Bearers eg: Data, SMS, USSD

WTP provides the protocol that allows for interactive browsing

(request/response) applications. It supports three transaction classes: unreliable with

no result message, reliable with no result message, and reliable with one reliable

result message. Essentially, WTP defines the transaction environment in which clients

and servers will interact and exchange data.The WDP layer operates above the bearer layer used by your

communications provider. Therefore, this additional layer allows applications to

operate transparently over varying bearer services. While WDP uses IP as the routing

protocol, unlike the Web, it does not use TCP. Instead, it uses UDP (User Datagram

Protocol) which does not require messages to be split into multiple packets and sent

out only to be reassembled on the client. Due to the nature of wireless

communications, the mobile application must be talking directly to a WAP gateway

(as opposed to being routed through myriad WAP access points across the wireless

Web) which greatly reduces the overhead required by TCP.

For secure communications, WTLS is available to provide security. It is based on SSL

and TLS.

WIRELESS APPLICATION ENVIRONMENT:


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The WAE defines the user interface on the phone. The application

development environment to facilitate the development of services that support

multiple bearers. To achieve this, the WAE contains the Wireless Markup Language

(WML), WMLScript- a scripting micro-language similar to JavaScript- and the

Wireless Telephony Application (WTA). These are the tools that allow WAP-based

applications to be developed.

The Wireless Application Environment (WAE) is the top-most

level in the WAP architecture. It is based on WWW and Mobile Telephony

technologies. The primary objective of the WAE is to provide the operators and

service providers an interoperable environment on which they can build applications

and services which, in turn, can be used in a wide variety of hand-held client

terminals. WAE includes the micro-browser that contains functionality for using not

only WML and WML Script as previously stated, but also Wireless Telephony

Application, namely (WTA and WTAI) -telephony services and programming

interfaces as well as content formats including well-defined data formats, images,

phone book records and calendar information.

The main idea behind the wireless application environment is

to create a general application environment based mainly on existing technologies and

philosophies of the World Wide Web .this environment should allow service

providers, software manufactures or hardware vendors to integrate their application so

they can reach a wide variety of different wireless platforms in an efficient way.

However, WAE does not dictate or assume any specific man-machine-interface

model, but allows for a variety of devices, each with its own capabilities and

probability vendor-specific extras. WAE has already integrated the following

technologies and adapted them for use in wireless environment with low powerhandled devices. HTML, java script, HDML forms the basis of the wireless markup

language and the scripting language WMLscript. The exchange formats for the

business cards and phone books vcard and for calendars vcalendar have been

included. URLs known from the web can be used. Furthermore, a wide range of

mobile telecommunication technologies have been adopted and integrated into the

wireless telephony application.

Besides relying on mature and established technology, WAE

has a focus on devices with very limited capabilities, narrow band environments and


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special security and access control features. The fist phase of the WAE specification

developed a whole application suite, especially for wireless clients as presented in the

following sections.

One global goal of the WAE is to minimize over-the-air and

resource consumption on the hand held device. A client issues an encoded request for

an operation on a remote server. Encoding is necessary to minimize the data sent over

the air and to save resources on the handheld devices.

Decoders in a gateway now translate this encoded request in to

a standard request as understood by the origin servers. This could be a request to get a

web page or a request to setup a call. The gateway transfers this request to the

appropriate origin server as if it came from a standard client.

The origin servers will respond to the request. The gateway

now encodes this response and its content and transfers the encoded response with the

content to the client. The WAE logical model does not only include this standard

request/response scheme, but also push devices. Then an origin server pushes content

to the gateway. The gateway encodes the pushed content and transmits the encoded

pushed content to the client.

With in a client several user agents can reside. User agents

include such items as browsers, phone books, messages editors etc. WAE does neither

specify the number of user agents nor their functionality, but assumes basic WML

user agents that support WML, WML script or both. Domain specific user agents with

varying architectures can be implemented. WTA user handles access to and

interaction with mobile telephone features (such as call control).


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WAE Logical Model

A sandwich layer that links the WAE to two session services-

one connection oriented operating above the Wireless Transaction Protocol and a

connectionless service operating above the Wireless Datagram Protocol.

The Wireless Session Protocol provides the Wireless

Application Environment a consistent interface with two services: connection-

oriented service to operate above the Transaction Layer Protocol (WTP) and a

connectionless service that operates above either secure or non-secure datagram

service (WDP).

Currently the protocols of the WSP family provide HTTP/1.1

functionality and semantics in a compact encoding, long lived session state with

session suspend and resume capabilities, a common facility for reliable and unreliable

data push as well as a protocol feature negotiation. These protocols are optimized to

be used in low-bandwidth bearer networks with relative long latency in order to

connect a WAP client to a HTTP server.

Origin servers Gateway Client

Web

Other

content

Encoders

&

WTA

WML

Other

WAP

Response

with

Push

request

Encoded

responses

with content

Encoded

push

Encoded


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WSP provides shared state between a client and a server to

optimize content transfer .HTTP a protocol WSP tries to replace with in the wireless

domain, is stateless, which already causes a lot of problems in fixed networks. State is

needed in web browsing eg: to resume browsing in exactly the same context in which

browsing has been suspended. This is an important feature for clients and servers.

Client users can continue to work where they left the browser or when the network

was interrupted, or users can get their customized environment every time they start

browser. Content providers can customize their pages to clients needs and do not have

to retransmit the same pages over and over again. WSP offers following features

needed for content exchange between operating clients and servers.

Session management:WSP introduces sessions that can be established from a client to a server

and maybe long lived. Sessions can also be released in an orderly

manner. Important for mobile applications are suspending and resuming a

session.

Capability of negotiation:Clients and servers can agree on a common level of protocol functionality

during session establishment. Content encoding:

WSP defines an efficient binary encoding for the content it transfers. WSP

offers content typing and composite objects.

While WSP is a general purpose session protocol WAP has specified

Wireless Session Protocol /Browsing (WSP/B) which comprises the protocols and

services most suitable for browsing type applications. In addition to the general

features WSP/B offers the following features

HTTP/1.1 functionality: WSP/B supports the functions of HTTP/1.1. Offerssuch as extensible request/reply methods, composite objects and content type

negotiation. WSP/B is a binary form of HTTP/1.1. Thus HTTP/1.1 content

headers are used to define content type, character set encoding languages etc.,


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but binary encoding are defined for well known headers to reduce the protocol

overheads.

Exchange of session headers: Client and server can exchange request/replyheaders that remain constant over the life time of the session. These headers

may include content types, character sets, languages, device capabilities and

other static parameters. WSP/B will not interpret header information but

passes all headers directly to service users.

Push and pull data transfer: Pulling data from the server is supported by theWSP/B by using the request/response mechanism from HTTP/1.1. WSP/B

supports three push mechanisms for the data transfer. a confirmed data push

with in the an existing session context, a non confirmed data push with in an

existing session context and a non confirmed data push with out an existing

session context.

Asynchronous data requests: Optionally WSP/B supports a client that can sendmultiple requests to a server simultaneously. This improves the efficiency for

the requests and replies can be now coalesced to in to fewer messages.

Latency is also improved, for each result can be send to the client as soon as it

is available.

WIRELESS TRANSACTION PROTOCOL:

Runs on top of a datagram service such as User Datagram

Protocol (UDP); part of the standard suite of TCP/IP protocols, to provide a simplified

protocol suitable for low bandwidth mobile stations. WTP offers three classes of

transaction service: unreliable one way request, reliable one way request and reliable

two way request respond. Interestingly, WTP supports Protocol Data Unit

concatenation and delayed acknowledgement to help reduce the number of messages

sent. This protocol therefore tries to optimize the user experience by providing the

information that is needed when it is needed- it can be confusing to received

confirmation of delivery messages when you are expecting the information itself. By

stringing several messages together, the end user may well be able to get a better feel

more quickly for what information is being communicated.


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The Wireless Transaction Protocol operates efficiently over

either secure or non-secure wireless datagram networks. It provides three different

kinds of transaction services, namely unreliable one-way, reliable one-way and

reliable two-way transactions. This layer also includes optional user-to-user reliability

by triggering the confirmation of each received message. To reduce the number of

messages sent, the feature of delaying acknowledgements can be used.

WTP is designed to run on very thin clients, such as mobile

phones. WTP offers several advantages to higher layers including an improved

reliability over datagram services, such as web browsing. There are three classes of

transaction services. Class0 provides unreliable message transfer without any result

message.Class1 and Class2 provide reliable message transfer, class1 without and

class2 with exactly one reliable result message.Class0, Class1, Class2 can have an

optional user acknowledgement.

WTP achieves reliability using duplicate removal,

retransmission, acknowledgement and unique transaction identifiers. No WTP class

requires any connection setup or teardown phase. This avoids unnecessary overheads

on the communication link. WTP allows for asynchronous transactions, abort of

transactions, concatenation of messages and can report the success or failure of

reliable messages. A special feature of WTP is the ability to provide user

acknowledgement or alternatively an automatic acknowledgement by WTP entity. If

user acknowledgement is required, a WTP user has to confirm every message

received by the entity.

The three service primitives offered by the WTP are TR-

Invoke to initiate a new transaction, TR-Result to send back the result of thepreviously initiated transaction and TR-Abort to abort an existing transaction. The

PDU s exchanged between two WTP entities for normal transaction are the invoke

PDU, ack PDU and result PDU.

WTP Class 0

Cass 0 offers an unreliable transaction service with out any

result messages. The transaction is stateless and hence cannot be aborted. The service


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is requested with the TR-Invoke.req primitive. Parameters are the source address

(SA), source port (SP), destination port (DP), destination address (DA). The A flag

determines whether the responder entity should generate an acknowledgement or a

user acknowledgement is to be used. WTP layer will transmit the user data (UD)

transparently to the destination. The class type, C indicates the class to be class 0. The

transaction handle H provides a simple index to uniquely identify the transaction and

is an alias for the tuple (SA, SP, DA, DP).

The WDP entity at the initiator sends an invoke PDU which the

responder receives. The WDP entity at the responder generates a TR-Invoke.ind

primitive with the same parameters as on initiator side except for H which now is for

the responder side. In this the responder does not acknowledge the message and theinitiator does not perform any retransmission and is recommended to use only when a

datagram service is required.

WTP Class0:

WTP Class 1:

Class 1 offers a reliable transaction service but without a result

message. The initiator sends an invoke PDU after a TR-invoke.req from a higher

TR-Invoke.reqTR-Invoke.ind

Initiator responder

Invoke


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layer. Here C=1, class being 1. The responder signals the incoming invoke via the

TR-invoke.ind primitive to the higher layer and acknowledges automatically with out

user intervention. For the initiator the transaction ends with the reception of

acknowledgement, the responder keeps the transaction state for some time to be able

to retransmit the acknowledgement if it receives the same invoke PDU again

indicating a loss of acknowledgement.

WTP Class1:

WTP Class 2;


Initiator responder

Invoke

Ack

TR-Invoke.cnfTR-Invoke.res (H)


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Class 2 transaction service provides the classical reliable

request/response transaction with one reliable message. The initiator requests a

service, the WTP entity sends the invoke PDU to the responder. The responder

indicates the request with the TR-Invoke.ind primitive to a user. The responder waits

for the processing of the request, the user on the responders side can finally give the

result UD* to the WTP entity on responder side using TR-Result.req. Now the result

PDU can be sent back to the to the initiator which implicitly acknowledges the invoke

PDU. Thus the initiator can indicate the successful transmission of the invoke

message and the result with the two service primitives TR-Invoke.cnf and TR-

Result.ind. A user may respond to this result with the TR-Result.res then an

acknowledgement PDU is generated which finally triggers the TR-Result.cnf

primitive on the responders side.


Initiator responder

Invoke

Result

TR-Invoke.cnfTR-Result.req (UD*,H)

Ack

TR-Result.ind

TR-Result.res

TR-Result.cnf


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WTP Class2:

WTLS incorporates security features that are based upon the

established Transport Layer Security (TLS) protocol standard. Includes data integrity

checks, privacy on the WAP Gateway to client leg and authentication.

The Wireless Transport Layer Security protocol is based on

Transport Layer Security (TLS) or formerly known as Secure Sockets Layer (SSL). It

is designed to be used with other WAP protocols and to support narrow-band

networks. It uses data encryption with a method that is negotiated at the start of the

session to provide privacy, data integrity, and authentication and denial-of-service

protection. The latter is needed in cases when data is replayed or not properly verified.When that happens, WTLS detects the misuse and rejects the data in order to make

many typical denial-of-service attacks harder to accomplish.

It is up to the applications to enable or disable WTLS features. Whether

that happens, it depends to their security requirements and the characteristics of the

underlying network, namely, does it use security services at the lower layer.

WTLS can provide different levels of security (for privacy, data integrity

and authentication) and has been optimized for low band width, high delay bearer net

works. WTLS take in to account the low processing power and very limited memory

capacity of the mobile devices for cryptographic algorithms. WTLS supports

datagram and connection oriented transport layer protocols.

Before data can be exchanged via WTLS, a secure session has to be

established. Figure shown below illustrates the sequence of service primitives needed

for full hand shake. The originator and the peer of the secure session can both

interrupt session establishment any time; eg: if the parameters proposed are not

acceptable.


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WTLS establishing a secure session

SEC-Create.req

SA,SP,DA,DP,KES,CS,CM

SEC-Create.cnf

SNM,KR,SID,KES,CS,CM

SEC-Create.ind

(SA,SP,DA, DP,KES,CS,CM)

SEC-Create.res

(SNM,KR,SID,KES,CS,CM)

SEC-Exchange.req

SEC-Exchange.cnf

CC

SEC-Commit.ind

SEC-Exchange.ind

SEC-Exchange.res

(CC)

SEC-Commit.req

SEC-Commit.cnf

Originator Peer


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The first step is to initiate the session with the SEC-Create primitive. Parameters are

source address (SA), source port(SP), of the originator, destination

address(DA),destination port(DP) of the peer. The originator proposes a key exchange

suite(KES) a cipher suite(CS) and a compression method(CM).The peer answers with

parameters for the sequence number mode(SNM) the key refresh cycle(KR), (how

often keys are refreshed with in this secure session) the session identifier (SID)

(which is unique with each peer )and the selected key exchange suite (KES),cipher

suite(CS),compression method(CM).The peer also issues a SEC- Exchange

primitive. This indicates that the peer wishes to perform public key authentication

with the client, ie the peer requests a certificate from the originator.

The first step of the secure session creation, the negotiation of

the security parameters and suites, is indicated on the originators side, followed by a

request for a certificate. The originator answers with its certificate and issues SEC-

Commit.req primitive .This primitive indicates that the hand shake is completed for

the originators side and that the originator now wants to switch in to the new ly

negotiated connection side. The certificate is delivered to the peer side and the SEC-

Commit is indicated. The WTLS layer of the peer sends back a confirmation to the

originator. This concludes the full handshake of the for secure session setup.

After setting up a secure connection between the two peers,

user data can be exchanged. This is done using the simple SEC-Unitdata primitive as

shown in figure below.


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WTLS Datagram Transfer

SEC-Unitdata has the same function as the T-DUnitdata on the

WDP layer; it transfers a datagram between a sender and a receiver. The higher layers

may use SEC-Unitdata instead of T-DUnitdata .Thus the parameters, SA, SP, DA,

DP, UD are same.

Although WTLS allows for different encryption mechanisms

with different key lengths, it is quite clear that due to computing power of the

handheld devices and export regulations in some countries, the encryption provided

cannot be very strong. However applications or users are free to put stronger

encryption on top of the whole protocol stack if required (and allowed ) - the

appropriate algorithms are available world wide. Future work in the WTLS layer

comprises consistent support for application level security ( eg: digital signatures )

and different implementation classes with different capabilities to select from.

Allows WAP to be bearer independent by adapting the

transport layer of the underlying bearer. WDP presents a consistent data format to the

higher layers of the WAP protocol stack thereby conferring the advantage of bearer

independence to application developers.

SEC-Unitdata.ind

Sender

SEC-Unitdata.req

Receiver


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The Wireless Datagram Protocol in WAP architecture covers

the Transmission Layer Protocols in an Internet model. As a general transport service,

WDP offers to the upper layers an invisible interface independent of the underlying

network technology used. In consequence of the interface common to transport

protocols, the upper layer protocols of the WAP architecture can operate independent

of the underlying wireless network. By letting only the transport layer deal with

physical network-dependent issues, global interoperability can be acquired using

mediating gateways.

The bearer services, over which WAP is designed to operate,

include short message, circuit-switched data and packet data services. Since the

bearers offer different types of quality of service with respect to throughput, error rate

and delays, the WDP is designed to either compensate for or tolerate these changes.

Also, WDP lists all the bearers that are supported and the techniques applied when

transmitting data over a certain bearer. These lists will change with new bearers being

added as the wireless market grows. At the T-SAP WDP offers a consistent datagram

transport service independent of the underlying bearer. The closer the bearer service

to IP, smaller the adaptation can be. If the bearer already offers IP services, UDP

(User Datagram Protocol) is used as WDP.

WDP offers source and destination port numbers used for

multiplexing and demultiplexing of data respectively. The service primitive to send a

datagram is T-Dunitdata.req with the destination address (DA), destination

port (DP), source address(SA), source port(SP) and user data(UD) as mandatory

parameters.


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WDP Service Primitives

Destination and source address are unique addresses for the

receiver and sender of the user data. The TDUnitdata.ind service primitive indicatesthe reception of data. Here destination and port addresses are optional parameters.

If a higher layer requests a service the WDP cannot fulfill, this

error is indicated with T-DError.ind service primitive. An error code (EC) is returned

indicating the reason for the error to the higher layer. However, this primitive must

not be used by the WDP to indicate problems with the bearer service, only for local

problems, such as a user data size that is too large.

If any error happen when WDP datagrams are sent from one WDP

entity to another (eg: destination is unreachable, no application is listening to the

specified destination or port etc. ) the wireless control message protocol (WCMP)

provides error handling mechanisms for WDP.WCMP can be used by the WDP

nodes and gateways to report errors. Typical WCMP messages are destination

unreachable (route, port, address unreachable), parameter problem, (errors in the

packet header), message too big, reassembly failure or echo request/reply

T-DUnitdata.req

T-DUnitdata.req

T-DError.ind

T-SAP

T-DUnitdata.ind

T-SAP


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An additional WDP management entity supports WDP and

provides information about the changes in the environment which may impact on

the correct operation of WDP. Important information is the current configuration

of the device, currently available bearer services, processing and memory resources

etc. Design implementations of these management is considered vendor specific

and thus outside the scope of WAP.

If the bearer already offers IP transmission, WDP (ie., UDP in

these case ) relies on the segmentation and reassembly capabilities of the IP layer

as specified. Otherwise, WDP has to include these capabilities, which is, eg.

necessary for the GSM SMS. The WAP specification provides many more

adaptations to almost all bearer services currently available or planned for thefuture.(WAP Forum 1998q), (WAP Forum 1998b)

WIRELESS APPLICATION ENVIRONMENT:

The WAE defines the user interface on the phone. The

application development environment to facilitate the development of services that

support multiple bearers. To achieve this, the WAE contains the Wireless Markup

Language (WML), WMLScript- a scripting micro-language similar to JavaScript- andthe Wireless Telephony Application (WTA). These are the tools that allow WAP-

based applications to be developed.

The Wireless Application Environment (WAE) is the top-most

level in the WAP architecture. It is based on WWW and Mobile Telephony

technologies. The primary objective of the WAE is to provide the operators and

service providers an interoperable environment on which they can build applications

and services which, in turn, can be used in a wide variety of hand-held client

terminals. WAE includes the micro-browser that contains functionality for using not

only WML and WML Script as previously stated, but also Wireless Telephony

Application, namely (WTA and WTAI) -telephony services and programming

interfaces as well as content formats including well-defined data formats, images,

phone book records and calendar information.

The main idea behind the wireless application environment is

to create a general application environment based mainly on existing technologies and

philosophies of the World Wide Web .this environment should allow service


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providers, software manufactures or hardware vendors to integrate their application so

they can reach a wide variety of different wireless platforms in an efficient way.

However, WAE does not dictate or assume any specific man-machine-interface

model, but allows for a variety of devices, each with its own capabilities and

probability vendor-specific extras. WAE has already integrated the following

technologies and adapted them for use in wireless environment with low power

handled devices. HTML, java script, HDML forms the basis of the wireless markup

language and the scripting language WMLscript. The exchange formats for the

business cards and phone books vcard and for calendars vcalendar have been

included. URLs known from the web can be used. Furthermore, a wide range of

mobile telecommunication technologies have been adopted and integrated into the

wireless telephony application.

Besides relying on mature and established technology, WAE

has a focus on devices with very limited capabilities, narrow band environments and

special security and access control features. The fist phase of the WAE specification

developed a whole application suite, especially for wireless clients as presented in the

following sections.

One global goal of the WAE is to minimize over-the-air and

resource consumption on the hand held device. A client issues an encoded request for

an operation on a remote server. Encoding is necessary to minimize the data sent over

the air and to save resources on the handheld devices.

Decoders in a gateway now translate this encoded request in to

a standard request as understood by the origin servers. This could be a request to get a

web page or a request to setup a call. The gateway transfers this request to the

appropriate origin server as if it came from a standard client.

The origin servers will respond to the request. The gateway

now encodes this response and its content and transfers the encoded response with the

content to the client. The WAE logical model does not only include this standard

request/response scheme, but also push devices. Then an origin server pushes content

to the gateway. The gateway encodes the pushed content and transmits the encoded

pushed content to the client.

With in a client several user agents can reside. User agents

include such items as browsers, phone books, messages editors etc. WAE does neither

specify the number of user agents nor their functionality, but assumes basic WML


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user agents that support WML, WML script or both. Domain specific user agents with

varying architectures can be implemented. WTA user handles access to and

interaction with mobile telephone features (such as call control).

WAE Logical Model

BEARERS

The WAP protocols are designed to operate over a variety of different bearer services,

including short message, circuit-switched data, and packet data. The bearers offer

differing levels of quality of service with respect to throughput, error rate, and delays.

The WAP protocols are designed to compensate for or tolerate this varying level of

service. Since the WDP layer provides the convergence between the bearer service

and the rest of the WAP stack, the WDP specification [WDP] lists the bearers that are

supported and the techniques used to allow WAP protocols to run over each bearer.

Origin servers Gateway Client

Web

Other

content

Encoders

&

WTA

WML

Other

WAP

Response

with

Push

request

Encoded

responses

Encoded

push

Encoded


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The list of supported bearers will change over time with new bearers being added as

the wireless market evolves.

EXAMPLE OF WAP NETWORK

The following is for illustrative purposes only. An example WAP network is shown in

Figure 3.


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In the example, the WAP client communicates with two servers in the wireless

network. The WAP proxy translates WAP requests to WWW requests thereby

allowing the WAP client to submit requests to the web server.

The proxy also encodes the responses from the web server into the compact binary

format understood by the client. If the web server provides WAP content (e.g.,

WML), the WAP proxy retrieves it directly from the web server. However, if the web

server provides WWW content (such as HTML), a filter is used to translate theWWW content into WAP content. For example, the HTML filter would translate

HTML into WML. The Wireless Telephony Application (WTA) server is an example

origin or gateway server that responds to requests from the WAP client directly. The

WTA server is used to provide WAP access to features of the wireless network

providers telecommunications infrastructure.


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WORKING OF WAP

WAP defines an application environment (WAE) aimed at enabling operators,

manufacturers, and content developers to develop advanced differentiating services

and applications including a micro browser, scripting facilities, e-mail, World Wide

Web (WWW) to mobile handset messaging, and mobile access to fax. The WAP

specifications continue to be developed by contributing members, who, through

interoperability testing, have brought WAP into the limelight of the mobile data

marketplace with fully functional WAPenabled devices (see

Fig).


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WAP MECHANISM

The WAP programming model is similar to the WWW programming model. This

provides several benefits to the application developer community, including a familiar

programming model, a proven architecture, and the ability to leverage existing tools

(e.g., Web servers, XML tools, etc.). Optimizations and extensions have been made in

order to match the characteristics of the wireless environment. Wherever possible,

existing Standards have been adopted or have been used as the starting point for the

WAP technology. The overall mechanism of WAP is shown in the below diagram.

WAP content and applications are specified in a set of well-known content formats

based on the familiar WWW content formats. Content is transported using a set of

standard communication protocols based on the WWW communication protocols. A


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micro browser in the wireless terminal co-ordinates the user interface and is

analogous to a standard web browser.

WAP defines a set of standard components that enable communication between

mobile terminals and network servers, including:

1. Standard naming modelWWW-standard URLs are used to identify WAP content

on the origin servers. WWW-standard URLs are used to identify local resources in a

device, e.g. Call Control functions.

2. Content typingAll WAP content is given a specific type consistent with WWW

typing. This allows WAP user agents to correctly process the content based on its

type.

3. Standard content formats WAP content formats are based on WWW technology

and

Include display markup, calendar information, electronic business card objects,

images and scripting language.

4. Standard communication protocols WAP communication protocols enable the

communication of browser requests from the mobile terminal to the network web

server. The WAP content types and protocols have been optimized for mass market,

and hand-held wireless devices. WAP utilizes proxy technology to connect between

the wireless domain and the WWW. The WAP proxy typically is comprised of the

following functionality:

5. Protocol Gateway The protocol gateway translates requests from the WAP

protocol stack (WSP, WTP, WTLS, and WDP) to the WWW protocol stack (HTTP

and TCP/IP).

6. Content Encoders and DecodersThe content encoders translate WAP content into

Compact encoded formats to reduce the size of data over the network. This

infrastructure ensures that mobile terminal users can browse a wide variety of WAP

content and applications, and that the application author is able to build content

services and applications that run on a large base of mobile terminals. The WAP


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proxy allows content and applications to be hosted on standard WWW servers and to

be developed using proven WWW technologies such as CGI scripting.

COMPETITORS OF WAP

Competition for WAP protocols could come from a number of sources:

Subscriber Identity Module (SIM) toolkitthe use of SIMs or smart cards in wireless

devices is already widespread and used in some of the service sectors.

Windows CEThis is a multitasking, multithreaded operating system from Microsoft

designed for including or embedding mobile and other space-constrained devices.

JavaPhoneSun Microsystems is developing Personal Java and a JavaPhone

API, which is embedded in a Java virtual machine on the handset. NEPs will be

able to build cellular phones that can download extra features and functions over the

Internet; thus, customers will no longer be required to buy a new phone to take

advantage of improved features.

The advantages that WAP can offer over these other methods are the following:

__ Open standard, vendor independent.

__ Network-standard independent.


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__ Transport mechanismoptimized for wireless data bearers.

__ Application downloaded from the server, enabling fast service creation and

introduction, as opposed to embedded software.


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THE FUTURE OF WAP

The tremendous surge of interest and development in the area of wireless data in

recent times has caused worldwide operators, infrastructure manufacturers, terminal

manufacturers, and content developers to collaborate on an unprecedented scale. This

collaboration is happening in an area notorious for the diversity of standards and

protocols. The collaborative efforts of the WAP Forum have devised and continue to

develop a set of protocols that provide a common environment for the development of

advanced telephony services and Internet access for the wireless market. If the WAP

protocols were to be as successful as transmission control protocol (TCP)/Internet

protocol (IP), the boom in mobile communications would be phenomenal. Indeed, theWAP browser should do for mobile Internet what Netscape did for the Internet.

As mentioned earlier, industry players from content developers to operators can

explore the vast opportunity that WAP presents. As a fixed-line technology, the

Internet has proved highly successful in reaching the homes of millions worldwide.

However, mobile users until now have been forced to accept relatively basic levels of

functionality, over and above voice communication are beginning to demand the

industry to move from a fixed to a mobile environment, carrying the functionality of a

fixed environment with it.

Initially, services are expected to run over the well-established SMS bearer, which

will dictate the nature and speed of early applications. Indeed, GSM currently does

not offer the data rates that would allow mobile multimedia and Web browsing. With

the advent of general packet radio services (GPRS) aiming at increasing the data rate

to 115 KBPS along with other emerging high-bandwidth bearers, the reality of access

speeds equivalent or higher to that of a fixed-line scenario becomes evermore

believable. GPRS is seen by many as the perfect partner for WAP, with its distinct

time slots serving to manage data packets in a way that prevents users from being

penalized for holding standard circuit switched connections.

Beneficants from WAP


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END USER:

Mobile phones have become dominant tools in communications and at the

same time the internet has become a de facto platform for information. By adopting a

common protocol the end user will be provided with more value added services whichare easy to access and easy to use directly from mobile phone Telephony oriented

services will be made easier to understand and to use.

OPERATORS:

The operators can differentiate by launching special services, for example for

banking stock trading, directory services etc. A further differentiation is that the

protocol makes it possible to tailor-make specific menus with in the mobile phones,

facilitating the use of the services. This customization can be made over the air.

INDUSTRY:

The telecommunication industry will be able to avoid overlapping costs and

investments if there is a common, open platform and tool for wireless messaging. This

is one of the first and important step in the evolution of wireless data/messaging

services which will increase the usage of data in wireless networks.


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Future directions

Even if WAP technology is developed recently and the first wireless terminal device

is entering the market WAP is just one step in a direction of new and better

technologies. The WAP services that are offered today seem to be complex to survive.

The future of wireless telephony, 4G or 3G will be making use of the packet

switching network such as GPRS. This will bring the wireless communication in to

another dimension and will give opportunities for transmission of both pictures and

videos.


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CONCLUSION

Corporate intranet and operator-specific solutions to reach wireless subscribers

Today. The WAP specification leverages and extends existing Internet standards,

Enabling application developers to tailor their content to the special needs of wireless

users. Handset manufacturers can enhance their product lines at minimal cost with

new usability benefits. Wireless service providers can establish a new and powerful

way to interact with their subscribers through a vital point of control in their own

network. The ultimate beneficiaries are wireless subscribers who can be more

productive than ever before.


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REFERENCES

1. WAP White Paper. AU-System Radio White Paper (1999): n. page.

World Wide Web. April, 2000.

Available: www.wapguide.com/wapguide/Auwap.pdf.

2. Wireless Application Protocol draws criticism.

Computing News Story (Technology Section) on CNN Interactive (2000): n. page.

World Wide Web. April, 2000.

Available:

http://www.cnn.com/2000/TECH/computing/03/14/wap.critics.idg/index.html


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3. WAP White Paper: Wireless Application Protocol. Wireless Internet Today

(1999): page. World Wide Web. April, 2000.

Available: www.wapforum.com/what/WAP_white_pages.pdf.

4. Shirky, Clay. WAP is in the Air. The Daily Feed from FEED Magazine (2000):

n. page. World Wide Web. April, 2000.

Available: www.feedmag.com/daily/dy020300.html.

5. Wireless application protocol: writing applications for the mobile internet, Pearson

education.

By-Sandeep Singhal, Thomas Bridgman Daniel Mauney, David Bevis

wap tech seminar

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