Post on 06-Apr-2018
8/2/2019 Wap Tech Seminar
1/47
8/2/2019 Wap Tech Seminar
2/47
2
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.
8/2/2019 Wap Tech Seminar
3/47
3
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.
8/2/2019 Wap Tech Seminar
4/47
4
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.
8/2/2019 Wap Tech Seminar
5/47
5
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
8/2/2019 Wap Tech Seminar
6/47
6
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.
8/2/2019 Wap Tech Seminar
7/47
7
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.
8/2/2019 Wap Tech Seminar
8/47
8
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
8/2/2019 Wap Tech Seminar
9/47
9
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.
8/2/2019 Wap Tech Seminar
10/47
10
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
8/2/2019 Wap Tech Seminar
11/47
11
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.
8/2/2019 Wap Tech Seminar
12/47
12
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.
8/2/2019 Wap Tech Seminar
13/47
13
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
8/2/2019 Wap Tech Seminar
14/47
14
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.
8/2/2019 Wap Tech Seminar
15/47
15
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)
8/2/2019 Wap Tech Seminar
16/47
16
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:
8/2/2019 Wap Tech Seminar
17/47
17
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
8/2/2019 Wap Tech Seminar
18/47
18
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).
8/2/2019 Wap Tech Seminar
19/47
19
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
8/2/2019 Wap Tech Seminar
20/47
20
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.,
8/2/2019 Wap Tech Seminar
21/47
21
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.
8/2/2019 Wap Tech Seminar
22/47
22
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
8/2/2019 Wap Tech Seminar
23/47
23
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
8/2/2019 Wap Tech Seminar
24/47
24
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;
TR-Invoke.reqTR-Invoke.ind
Initiator responder
Invoke
Ack
TR-Invoke.cnfTR-Invoke.res (H)
8/2/2019 Wap Tech Seminar
25/47
25
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.
TR-Invoke.reqTR-Invoke.ind
Initiator responder
Invoke
Result
TR-Invoke.cnfTR-Result.req (UD*,H)
Ack
TR-Result.ind
TR-Result.res
TR-Result.cnf
8/2/2019 Wap Tech Seminar
26/47
26
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.
8/2/2019 Wap Tech Seminar
27/47
27
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
8/2/2019 Wap Tech Seminar
28/47
28
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.
8/2/2019 Wap Tech Seminar
29/47
29
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
8/2/2019 Wap Tech Seminar
30/47
30
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.
8/2/2019 Wap Tech Seminar
31/47
31
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
8/2/2019 Wap Tech Seminar
32/47
32
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
8/2/2019 Wap Tech Seminar
33/47
33
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
8/2/2019 Wap Tech Seminar
34/47
34
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
8/2/2019 Wap Tech Seminar
35/47
35
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.
8/2/2019 Wap Tech Seminar
36/47
36
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.
8/2/2019 Wap Tech Seminar
37/47
37
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).
8/2/2019 Wap Tech Seminar
38/47
38
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
8/2/2019 Wap Tech Seminar
39/47
39
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
8/2/2019 Wap Tech Seminar
40/47
40
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.
8/2/2019 Wap Tech Seminar
41/47
41
__ Transport mechanismoptimized for wireless data bearers.
__ Application downloaded from the server, enabling fast service creation and
introduction, as opposed to embedded software.
8/2/2019 Wap Tech Seminar
42/47
42
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
8/2/2019 Wap Tech Seminar
43/47
43
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.
8/2/2019 Wap Tech Seminar
44/47
44
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.
8/2/2019 Wap Tech Seminar
45/47
45
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.
8/2/2019 Wap Tech Seminar
46/47
46
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
8/2/2019 Wap Tech Seminar
47/47
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