Wap Protocols

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WAP Architecture An overview of the WAP architecture, its protocols and components, and compares this architecture with the

typical internet architecture when using the world wide web.

The basis for transmission of data is formed by different bearer services. WAP does not specify bearer

services, but uses existing data services and will integrate further services.

No special interface has been specified between the bearer service and the next higher layer, the transport

layer with its wireless datagram protocol (WDP) and the additional wireless control message protocol

(WCMP),because the adaptation of these protocols are bearer-specific

The transport layer oers a bearer independent, consistent datagram!oriented service to the higher

layers o the WAP architecture"ommunication is done transparently over one of the available bearer

services.

The transport layer service access point (T!#AP) is the common interface to be used by higher layers

independent of the underlying networ!.

The next higher layer, the security layer with its wireless transport layer securityprotocol WT$# offers

its service at the security #AP (#%C!#AP). "t can offer data integrity, privacy, authentication, and #some$

denial-of-service protection.

The WAP transaction layer with its wireless transaction protocol (WTP) offers a lightweight transaction

service at the transaction #AP (T&!#AP). This service efficiently provides reliable or unreliable re%uests

and asynchronous transactions.

The session layer with the wireless session protocol (W#P) currently offers two services at the session!#AP (#!#AP), one connection-oriented and one connectionless if used directly on top of W&P

'inally the application layer with the wireless application environment (WA%) offers a framewor! for

the integration of different www and mobile telephony applications.

WAP does not always force all applications to use the whole protocol architecture. Applications can use

only a part of the architecture

Components and interace o the WAP '" architecture

&ifferent scenarios are possible for the

integration of WAP

components into existing

wireless and fixed networ!s.

(n the left side, different fixed

networ!s, such as the

traditional internet and the

public switched telephone

networ! #P)TN$, are shown.

ne cannot change protocols

and services o these eisting

networ*s so several new

elements will be implemented

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between these networ*s and the WAP!enabled wireless, mobile devices in a wireless networ*on the right!

hand side"

The current www in the internet offers web pages with the help of 4T15 and web servers. To be able to

browse these pages or additional pages with handheld devices, a wireless mar!up language #W15$ has been

defined in WAP. )pecial filters within the fixed networ! can now translate 4T15 into W15, web servers can

already provide pages in W15, or the gateways between the fixed and wireless networ! can translate 4T15

into W15. These gateways not only filter pages but also act as proxies for web access.

W15 is additionally converted into binary W15 for more efficient transmission.

'" Wireless datagram protocol The wireless datagram protocol (WDP) operates on top o many dierent bearer services capable of

carrying data.

W&P hides details of the various bearer networ!s from the other layers of WAP

At the T-)AP W&P offers a consistent datagram transport service. To offer this consistent service, the

adaptation needed in the transport layer

W&P offers more or less the same services as 2&P.

W&P offers source and destination port numbers used or multipleing and demultiplexing of data

respectively.

The service primitive to send a datagram is, TD+nitdata"re with (&A,&P, )A, )P, and 2&)

The service primitive to send a datagram is TD+nitdata" re with the destination address (DA),destination

port (DP), #ource address (#A), source port (#P), and user data (+D) as mandatory parameters.&estination

and source address are uni%ue addresses for the receiver and sender of the user data..

The T!D+nitdata"ind service primitive indicates the reception of data. 4ere destination address and port

are only optional parameters.

rror is indicated with the T!D%rror"ind service primitive .An error code (%C) is returned indicating the

reason for the error to the higherlayer. W&P is not allowed to use this primitive to indicate problems with thebearer service.

The wireless control message protocol (WCMP)provides error handling mechanisms for W&P used by W&P

nodes and gateways to report errors. such messages are,

#Typical W1P messages are destination unreachable #route, port, address unreachable$, parameter

problem #errors in the pac!et header$, message too big, reassembly ailure, or echo reuest-reply.

W1P error messages must not be sent as response to other W1P error messages.

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"f the bearer already offers "P transmission, W&P #i.e., 2&P in this case$ relies on the segmentation #called

fragmentation in the "P context$ and reassembly capabilities

An additional WDP management entity supports W&P and provides information about changes in the

environment

." Wireless transport layer security"f re%uested by an application, a security service, the wireless transport layersecurity (WT$#), can be

integrated into the WAP architecture on top of W&P.

WT5) can provide different levels of security

WT5) is based on the T5)6))5 #Transport 5ayer )ecurity$ protocol optimi7ed for low-bandwidth communication channels

provides

privacy #encryption$

data integrity #1As$

authentication #public-!ey and symmetric$

mploys special adapted mechanisms for wireless usage

secure sessions is established b6w nodes to exchange data#'ull 4andsha!e$

(ptimised algorithms for low 8W

Provides low processing power and limited memory

)upports datagram and connection oriented transport layer protocols.

WTLS establishing a secure sessionBefore data can be exchanged via WTLS, a secure session has to be established.Thissession establishment consists of several steps- called f ull handshake

service primitives

)-reate re%9 to initiate the session#)A, )P of the originator, &A, &P of the peer.$

The originator proposes a !ey exchange suite #)-:)A$, a cipher suite #)-&), "&A$ and a compression

method #1$

)-reate res9 The peer answers with parameters for the se%uence number mode #)N1$, the !ey

refresh cycle #:$ #i.e., how often !eys are refreshed within this secure session$, the session identifier

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#)"&$ #which is uni%ue with each peer$, and the selected !ey exchange suite #)


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The responder will not send the ac! automatically but waits for T:-"nvo!e.res service primitive from the user.

WTP lass 9

Provides reliable service without user ac!

T:-"nvo!e.ind9 The initiator or user indicates the re%uest with this primitive.

T:-:esult.re%9 The responder gives the result to WTP entry using T:-:esult.re%

The result.P&2 is sent bac! to initiator which is implicitly ac!nowledged.

T:-"nvo!e.cnf9 This primitive is used to confirm the re%uest

T:-:esult.ind9 The indicator can indicate the result

T:-:esult.res9 The user responds to the result with T:-:esult.T:-:esult.cnf9 confirmation on the receiver side.

$asic transaction WT% class 2 no user ac!no"ledgement

$asic transaction WT% class 2 "ith user ac!no"ledgement

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+f the calculation of the result takes some time, the responder can put the initiatoron hold on& to prevent a retransmission of the invoke ! as the initiator mightassume packet loss if no result is sent back ithin a certain timeframe.

'( Wireless session protocol W)P provides a shared state between a client and a server to optimi7e content transfer. W)P provides

applications with an interface for two session services

The wireless session protocol (W#P) has been designed to operate on top of the datagram service W&P or

the transaction service WTP.

W)P provides a shared state between a client and a server to optimi7e content transfer.

W)P offers the following general features needed for content exchange between cooperating clients and servers9

#ession management0 W)P introduces sessions that can be established from a client to a server and

may be long lived. )essions can also be released in an orderly manner. The capabilities of suspending

and resuming a session are important to mobile applications.

Capability negotiation0 lients and servers can agree upon a common level of protocol functionality

during session establishment.

Content encoding0 W)P also defines the efficient binary encoding for the content it transfers.

Wireless session protocol-browsing (W#P-3) which comprises protocols and services most suited for

browsing-type applications. W)P68 offers the following features adapted to web browsing9

4TTP-'"' unctionality0 W)P68 supports the functions 4TTP63.3 offers, such as extensible re%uest6replymethods, composite obBects,and content type negotiation. W)P68 is a binary form of 4TTP63.3.4TTP63.3

C %change o session headers0 lient and server can exchange re%uest6reply headers that remain constant

over the lifetime of the session.

C Push and pull data transer0 Pulling data from a server is the traditional mechanism of the web. This is also

supported by W)P68 using the re%uest6response mechanism from 4TTP63.3. Additionally, W#P-3 supports

three push mechanisms or data transer0a conirmed data pushwithin an existing session context, a non!

conirmed data pushwithin an existing session context, and a non!conirmed data push without an eisting

session contet"

C Asynchronous reuests0 (ptionally, W)P68 supports a client that can send multiple re%uests to a server

simultaneously.

WS%)$ over WT%W)P68 uses the three service classes of WTP. lass 0 is used for unconfirmed push, session resume, and

session management. onfirmed push uses class 3, method invocation, session resume, and session

management class .

WS%)$ session establishment

#!Connect"reprimitive, a client can re%uest a new session. Parameters are the server address (#A), the

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client address (CA), and the optional client header (C4) and reuested capabilities (&C).

#!Connect"indprimitive indicates a new session. "f the server accepts the new session it answers with an #!

Connect"res,negotiated capabilities (5C) needed for capability negotiation.

WTP now transfers the connreply PD+bac! to the clientE #!Connect"cn confirms the session establishment.

WS%)$ session suspension and resume

"f, for example, a client notices that it will soon be unavailable, e.g., the bearer networ! will be

unavailable due to roaming to another networ! or the user switches off the device, the client can suspend the

session. )ession suspension will automatically abort all data transmission and free7e the current state of thesession on the client and server side. A client suspends a session with #!#uspend"re, WTP transfers the

suspend PD+ to the server. W)P68 will signal the suspension with #!#uspend"ind on the client and server

side. The only parameter is the reason & for suspension.

A client can later resume a suspended session with #!&esume"re. Parameters are server address (#A) and

client address #A$. Terminating a session is done by using the )-&isconnect.re% service primitive. Terminating

a session is done by using the )-&isconnect.re% service primitive . This primitive aborts all current method or

push transactions used to transfer data. &isconnection is indicated on both sides using )-&isconnect.ind. The

reason : for disconnection can be, e.g., networ! error, protocol error, peer re%uest, congestion, and maximum

)&2 si7e exceeded.

W#P-3 session termination 0

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W#P-3 completed Transaction

WS%)$ non-con#rmed push

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WS%)$ as*nchronous unordered re+uests

WS%)$ as connectionless session serviceThe three service primitives available for connectionless session service9 #!+nit!Method2nvo*e"re to re%uest

an operation on a server, #!+nit!Method&esult"re to return results to a client, and #!+nit!Push"re to push

data onto a client. Transfer of the P&2s #method, reply and push$ is done with the help of the standardunreliable datagram transfer service of W&P.

W#P-3 as connectionless session service



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Wireless application environmentThe main idea behind the wireless application environment (WA%) is to create a general-purpose application

environment based mainly on existing technologies and philosophies of the world wide web. This environment

should allow service providers, software manufacturers, or hardware vendors to integrate their applications

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

WA has already integrated the following technologies and adapted them for use in a wireless environment with

low power handheld devices. 4T15 , the handheld device mar!up language 4&15, wireless mar*up

language (WM$) and the scripting language WM$script. The exchange formats for business cards and phoneboo!s vCard and for calendars vCalendar have been included.

+&$s from the web can be used.

wireless telephony application (WTA)

W,E logical model

(ne global goal of the WA is to minimi7e over-the-air traffic and resource consumption on the

handheld device.

A client issues an encoded re%uest for an operation on a remote server.

Agateway now translate this encoded re%uest into a standard re%uest as understood by the origin

servers.

The origin servers will respond to the re%uest. The gateway now encodes the response and its content #if

there is any$ and transfers the encoded response with the content to the client.

)everal user agentscan reside within a client. 2ser agents include such items as9 browsers, phoneboo!s,

message editors etc. WA does not specify the number of user agents or their functionality

Aa user agent proile (+APro), which describes the capabilities of a user agent. apabilities may be

related to hardware or software. xamples are9 display si7e, operating system, browser version,

processor, memory si7e, audio6video codec, or supported networ! types.


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