Support for Mobility Wireless Application Protocol

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Support for Mobility --- Wireless
Application Protocol
SHEN WANG 4245105
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Outline

• Introduction to WAP
• The WAP Model
• WAP 1.x -reference model and protocols
• WAP 2.0 Stack Architecture
• WAP 2.0 example protocol stacks

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WAP -Wireless Application Protocol

• Goals
• deliver Internet content and enhanced services to
  mobile devices and users (mobile phones, PDAs)
• independence from wireless network standards
• open for everyone to participate, protocol
  specifications will be proposed to
  standardization bodies
• applications should scale well beyond current
  transport media and device types and should also
  be applicable to future developments
• Platforms
• e.g., GSM (900, 1800, 1900), CDMA IS-95, TDMA
  IS-136,
• 3rdgeneration systems (IMT-2000, UMTS,
  W-CDMA,)
• Forum
• was WAP Forum, co-founded by Ericsson, Motorola,
  Nokia, Unwired Planet.
• now Open Mobile Alliance www.openmobilealliance.o
  rg

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WAP -scope of standardization

• Browser
• micro browser, similar to existing, well-known
  browsers in the Internet
• Script language
• similar to Java script, adapted to the mobile
  environment
• WTA/WTAI
• Wireless Telephony Application (Interface)
  access to all telephone functions
• Protocol layers
• transport layer, security layer, session layer
  etc.

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The WWW Programming Model

• The WWW standards specify many of the mechanisms
  necessary to build a general-purpose application
  environment, including
• Standard naming model URL
• Content typing for example image, audio, video
• Standard content formats for example, HTML,
  JavaScript
• Standard Protocols HTTP

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The WAP Programming Model

• The most significant enhancements
• Push
• Telephony Support (WTA)
• The WAP content types and protocols have also
  been optimised for mass market, hand-held
  wireless devices.

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The WAP Proxies

• Protocol Gateway The protocol gateway
  translates requests from a wireless protocol
  stack to the WWW protocols.
• Content Encoders and Decoders The content
  encoders can be used to translate WAP content
  into a compact format .
• User Agent Profile Management User agent
  profiles describing client capabilities and
  personal preferences are composed and presented
  to the applications.
• Caching Proxy A caching proxy can improve
  perceived performance and network utilisation by
  maintaining a cache of frequently accessed
  resources.

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WAP Network Elements
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WAP 1.x -reference model and protocols
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WDP -Wireless Datagram Protocol

• uses directly transports mechanisms of different
  network technologies
• offers a common interface for higher layer
  protocols
• allows for transparent communication using
  different transport technologies
• Goals of WDP
• create a worldwide interoperable transport system
  with the help of WDP adapted to the different
  underlying technologies
• transmission services such as SMS, GPRS in GSM
  might change, newservices can replace the old
  ones

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General WDP Architecture
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WDP -Service Primitives
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WTLS -Wireless Transport Layer Security

• Goals
• data integrity
• prevention of changes in data
• privacy
• authentication
• creation of authenticated relations between a
  mobile device and a server
• protection against denial-of-service attacks
• protection against repetition of data and
  unverified data
• WTLS
• is based on the TLS (Transport Layer Security)
  protocol (former SSL, Secure Sockets Layer)
• optimized for low-bandwidth communication
  channels

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WTP -Wireless Transaction Protocol

• Goals
• support of different communication scenarios
• class 0unreliable message transfer
• class 1reliable message transfer without result
  message
• class 2reliable message transfer with exactly
  one reliable result message
• supports peer-to-peer, client/server and
  multicast applications
• low memory requirements, suited to simple devices
  (lt 10kbyte )
• efficient for wireless transmission
• segmentation/reassembly
• selective retransmission
• header compression
• optimized connection setup (setup with data
  transfer)

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Three Transaction Classes

• Class 0 unreliable datagram service
• Example unreliable push service
• Class 1 reliable datagram service
• An invoke message is not followed by a result
  message
• Example reliable push service
• Class 2 basic invoke/response transaction
  service
• An invoke message is followed by exactly one
  result message
• Example typical web browsing

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WTP Class 0 transaction
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WTP Class 1 transaction
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WTP Class 2 transaction
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WSP -Wireless Session Protocol

• Goals
• HTTP 1.1 functionality
• Request/reply, content type negotiation, ...
• support of client/server, transactions, push
  technology
• key management, authentication, Internet security
  services
• session management (interruption, resume,...)

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WSP protocols
WSP
Connection mode (uses WTP)
Connectionless mode (uses WDP)
Session Management (class 0,2) Method Invocation
(class 2) Push (class 0) Confirmed Push (class
1) Session Suspend/Resume (class 0,2)
Method Invocation Push (in general unreliable)
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WSP session establishment
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WSP session suspend/resume
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WSP session termination
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WSP method invoke
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WSP -confirmend/non-confirmed push
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WSP over WDP
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WAE-Wireless Application Environment

• Goals
• network independent application environment for
  low-bandwidth, wireless devices
• integrated programming model with high
  interoperability
• Requirements
• device and network independent, international
  support
• considerations of slow links, limited memory, low
  computing power, small display, simple user
  interface (compared to desktop computers)
• Components
• WML XML-Syntax, the WAP equivalent to HTML
• Makes optimal use of small screens
• Employs the concept of decks and cards
• WMLScript procedure, loops, conditions, ...
  (similar to JavaScript)
• makes minimal demands on memory and CPU usage,
  omitting a number of functions that are not
  required for wireless applications.
• a scaled-down, simplified script, developed
  specifically to fit the WAP architecture of decks
  and cards
• WTA telephone services, such as call control,
  voice mail, ... (accessible from WML/WMLScript)

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WTA -Voice box example
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WAP 2.0 (2001)

• New for developers
• Wireless Profiled TCP
• Wireless Profiled HTTP
• New applications
• Color graphics
• Animation
• Large file download
• Pop-up/context sensitive menus
• Goal integration of WWW, Internet, WAP, i-mode

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WAP 2.0 stack architecture
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WAP 2.0 example protocol stacks
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Summary of WAP 2.0 Architecture

• A consistent architecture composed of standard
  components
• Interoperability is also ensured for all the
  different functions
• Using WAP, the developer does not have to create
  several different versions of the application for
  mutually incompatible environments.

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Three Questions

• Question 1
• What are the most significant enhancements WAP
  has added to the WWW programming model?
• Answer Push and Telephony Support (WTA)
•  
• Question 2
• What are the three classes of transaction service
  that Wireless Transaction Protocol provides? Give
  a simple description.
• Answer
• Class 0 Unreliable invoke message with no result
  message
• Class 1 Reliable invoke message with no result
  message
• Class 2 Reliable invoke message with exactly one
  reliable result message
• Question 3
• Because several of the services in the WAP 2.0
  stack can be provided using different protocols
  based on the circumstances, there are more than
  one possible stack configurations. Please give
  three example configurations.
• Answer WAP 1.x Gateway, WAP HTTP Proxy with
  Profiled TCP and HTTP, and WAP Direct Access.

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• Thank you!