Introduction to Mobile Computing

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Introduction to Mobile Computing

• Aleksandar Kovacevic, renesto_at_gmail.com
• Mina Micanovic, minica82_at_EUnet.yu
• Veljko Milutinovic, vm_at_etf.bg.ac.yu

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Wireless Mobile or Mobile Wireless?

• Wireless communication systems are type of
  communication system
• Dimensions of mobility
• The set of properties that distinguishes the
  mobile computing system from stationary
  computing system

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Dimensions of Mobile Computing

• Location awareness
• Network connectivity quality of service (QOS)
• Limited device capabilities
• Limited power supply
• Support for a wide variety of user interfaces
• Platform proliferation
• Active transactions

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Mobile Development Frameworks and Tools
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Mobile Development Frameworks and Tools

• Fully Centralized
• Frameworks and Tools
• N-Tier Client-Server
• Frameworks and Tools

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Fully Centralized Frameworks and Tools

• Have custom-designed clients
• Embedded in nature
• Designed to do only one thing

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Fully Centralized Frameworks and Tools

• Applies
• QOS
• Limiter power supply
• Active transactions
• Location awareness
• Do not apply
• Platform proliferation
• Limited device capabilities
• Support for variety of user interfaces

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Examples

• Call centers
• Battlefield systems
• Grocery store

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N-Tier Client-Server Framework and Tools

• N-Tier -Any Number of Tiers No Limits
• 3-Tier
• Client (User Agent)
• Application Server
• Database

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Basic problems

• Code portability
• Mobility

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Needs

• Layer of Software
• Performance and system requirements

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Selection of the Frameworks and Tools

• Thin-Client Wireless Client-Server
• Thick-Client Wireless Client-Server
• Stand-alone Applications

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Thin-Client Wireless Client-Server

• Browser that loads markup code (Web-model)
• No concern about environment
• Server-side structure
• Example WAP with his WML

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Thick-Client Wireless Client-Server

• Client application-custom application
• Using the client as a means of storing data for
  the offline business logic performs
• Does not need to be centralized
• Having thick clients is more difficult

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Difficulties???

• Restricted resources
• Deployment and provision problem
• Operating system or virtual machine
• Programming environment

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Examples

• Operating system
• Windows CE
• Symbian
• Virtual Machine
• J2ME

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Stand-alone Applications

• They do not need networking components
• Needs of synchronization with some external
  system periodically

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Some products
Connectivity Platform Stand-alone Networked Networked
Connectivity Platform Stand-alone Wired Wireless
Mobile Platforms WAP
Mobile Platforms Symbian Symbian Symbian
Mobile Platforms BREW BREW BREW
Mobile Platforms Java Java Java
Mobile Platforms .NET .NET .NET
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JAVA - features

• Object oriented language
• Complete code mobility
• Weak mobile agent ability
• It is a platform

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J2ME

• Addresses the needs of
• two categories of devices
• Personal, mobile, connected information devices
  (CLDC)
• Shared, fixed, connected information devices
  (CDC)

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CLDC/MIDP Features(1)

• Providing
• a virtual machine for providing language
  features
• a security framework for tasks such as
  downloading MIDlets (J2ME CLDC/MIDP applications)

MIDP - Mobile Information Device Profile
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CLDC/MIDP Features(2)

• Providing
• a reasonable amount of functionalityfor input
  and output
• some internationalization capabilities
• a reasonable amount of networking capabilities

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KVM

• Does not provide
• Floating point arithmetic
• Support for JNI
• Thread grouping
• Full-blown exception
• Automatic garbage collection of unused objects
• Weak references

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CLDC/MIDP features

• Providing a security framework for tasks such as
  downloading MIDlets (J2ME CLDC/MIDP applications)

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CLDC/MIDP features

• Providing a reasonable amount of functionality
  for input and output

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Internationalization capabilities

• Provides I/O stream readers that can handle
  different character encoding schemes
• Two ways of internationalization
• Dynamic
• Static

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Profiles

• The areas addressed by profiles are the
  following
• Download and installation of application
• Life-cycle management of application
• User interface feature
• Database functionality
• Event handling

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CLDC profiles

• MIDP (Mobile Information Device Profile)
• Widely known and accepted
• Personal Digital Assistant Profile (PDAP)
• etc.

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MIDP

• Designed for devices with assumed
• characteristics
• Small displays (96x24,11 shaped pixels, depth
  1bit)
• Min 128kB of nonvolatile memory (for storing
  application itself)
• Wireless connection to the internet
• Min of 8kB of nonvolatile memory (for use by the
  application)
• ITU-T phone keypad

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Overview of the CLDC and MIDP Java APIs

• J2SE-like APIs inherited from the J2SE
  environment
• java.lang.
• java.io.
• java.util.
• CLDC-specific APIs
• javax.microedition.io (connector class)

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Networking Capabilities

• J2SE assumes the availability of a TCP/IP
  connection
• CLDC defines a connection framework in its Java
  API
• example WAP-style connections (WDP/UDP)

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Review of MIDP APIs

• Timers
• java.util.Timer
• java.util.TimerTask
• Networking
• HTTP implementation
• javax.microedition.io. holds HttpConnection

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Review of MIDP APIs

• Storage
• javax.microedition.rms. (RMS-Record Management
  System) for storing and retrieving data
• User Interface
• javax.microedition.lcdui.user interface APIs to
  build interfaces for MIDlets

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Hello MIDP example

• For a J2ME class to qualify as a MIDlet,
• it has to do the following
• Extend the MIDlet class
• Implement the following methods
• startApp()
• pauseApp()
• destroyApp(boolean b)

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Hello MIDP example

• import javax.microedition.midlet.
• import javax.microedition.lcdui.
• public class HelloMIDP extends MIDlet implements
  CommandListener
• public static final String HELLO Hello MIDP
• private DIsplay mDIsplay
• private Command mExit
• public HelloMIDP()
• mDisplay Display.getDIsplay(this)
• mExit new Command(Exit, Command.SCREEN, 1)

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Hello MIDP example

• public void startApp()
• TextBox myMessage new TextBox(HELLO, HELLO,
  256, 0)
• myMessage.addCommand(mExit)
• myMessage.addCommand((CommandListener) this)
• mDisplay.setCurrent(mDIsplay)
• public void pauseApp()
• public void commandAction(Command aCommand,
  Displayable aDisplayHandle)
• if (aCommand mExit)
• destroyApp(false)
• public void destroyApp(boolean b)
• notifyDestroyed()

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Suns Development Kit

• Offers following components
• KToolbar (GUI)
• Preverifier
• Compiler
• Emulators
• Emulation of Performance

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Dimensions of Mobility by CLDC and Profiles

• Location awareness
• no treatment
• javax.microedition.location
• Network QOS
• Limited Device Capabilities
• Limited Power Supply Management
• Support for a Large Variety of User Interfaces
• Platform proliferation
• Active Transactions

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XML J2ME

• Types of parsers
• Model Parsers
• Push Parsers
• Pull Parsers

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Using UML to Model J2ME Applications

• Class Diagrams
• State Diagrams
• Component Diagrams
• Sequence Diagrams

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CDC

• Targeted at environments where more than 512kB
  (usually about 2MB) of memory is available for
  the Java environment
• CDC Profiles are built on top of the Foundation
  Profile
• CDC has his own virtual machine (CVM-C Virtual
  Machine)
• CVM supports all of the features that the J2SE
  VM does

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Java Card

• Smart cards embedded processor or electronic
  memory device
• Java Card API allows interoperability between
  different card readers/writes and cards
  regardless of the manufacturer and Java Card API
  implementer

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Java Card
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Three Types of Smart Cards

• IC (Integrated Circuit)
• Memory Cards
• IC Microprocessor Cards
• Optical Memory Cards

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JINI

• Java Intelligence Network Infrastructure
• a base technology for ad-hoc networking
• Basic transaction that JINI provides
• Lookup
• Discovery
• Events
• Leasing
• Joining
• Transaction Management

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JINI Specification

• Most todays implementations are not designed
  for mobile devices
• There are some that offer mobilized JINI
• PSINaptic

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Java-based Peer-to-Peer Protocol

• JXTA peer-to-peer protocol
• Implementation on J2ME
• Direct Implementation (JXTA APIs - provided on
  J2ME device)
• Indirect Implementation (JXTA through proxies)

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BREW

• BREW (Binary Run-time Environment for Wireless)
• It is built directly on hardware
• Software Development Kit (SDK)

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BREW SDK Overview

• http//www.qualcomm.com/brew
• register as a developer
• download BREW SDK
• offered only as a integrate set of components
  with MS Visual C 6.0
• You get this applications
• BREW MIF Editor
• BREW Device Configurator
• BREW Emulator
• BREW Image Authoring Tool
• BREW ARM Compiler
• Image Converter
• BREW Resource Editor
• BREW Pure Voice Converter
• BREW AppLoader
• BREW Grinder
• BREW TestSig Generator and AppSigner

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Building and Deploying a BREW Application

• Download the SDK and get started
• Obtain a Verisign Class 3 certificate
• Get a BREW phone
• Register as a BREW developer
• Obtain a Class ID for your application
• Perform a unit test and send it to a testing lab
• Perform a pricing and carrier evaluation

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Hello BREW

• AEEClsCreateInstance
• BREW Run-time environment
• HelloBREW_HandleEvent
• EventHandler

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Architectural Concerns About BREW Application

• Everything in BREW is event driven (tight
  coupling to the hardware platform)
• Two groups of APIs you can use
• those provided by qualcomm
• those provided by third-party vendors
• BREW API is still developing in C

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Windows CE

• Different flavors
• of the Windows CE OS,
• depending on
• hardware platform.
• Pocket PC
• Windows CE .NET
• Pocket PC 2002

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Tools to build Applications

• Embedded Visual C
• separate from Visual Studio
• Emulators and a debugger is provided
• exception handling, run-time debugging
• Embedded Visual Basic
• can be developed faster
• no ability to be tuned and optimized for
  resource-starved mobile devices
• Smart Device Extensions for .NET
• Microsoft Mobile Internet Toolkit

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eMbedded Visual C

• Compilers available for
• ARM
• MIPS
• Intels x86
• PowerPC
• Hitachi processors

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eMbedded Visual C

• Provides
• a subset of the Win32 APIs for building Windows
  CE applications
• a subset of the MFC (Microsoft Foundation
  Classes) libraries
• a set of classes specific to the Windows CE
  platform

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Things You Should keep in mind

• Graphics are expensive
• Use events instead of polling when possible
• Economize with your memory (saving power)
• Provided functionality of getting the status of
  the Power Consumption
• useful for testing application
• useful to change behavior of application
• Clean up memory resources whenever you get
  WM_HIBERNATE event

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Databases on Windows CE

• Three ways to store data
• MS SQL Server Windows CE Edition
• most functionality
• takes the most resources
• offers only subset of its desktop/server version
• views
• stored procedure
• CEDB
• small and simple database
• its not relational database
• File System
• fewer resources
• increases the application

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Windows CE and Web Services

• Importance of XML-based Web Service
• .NET has Web Service-based functionality based on
  two key technologies
• WSDL (Web Service Definition Language)
• SOAP (Simple Object Access Protocol)

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Microsoft Smart Phone

• Microsoft Smart Phone 2002, Microsoft's attempt
  to enter the mobile technology market
• It can host custom applications written using
  smart phone SDK. SDK is provided as a plug-in
  for eVC

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WAP

• WAP Wireless Application Protocol
• Installed on almost every mobile phone
• Basics about WAP
• WAP is intended for thin clients
• all logic calculated on the server
• simple display instructions in some markup
  language are done by the client
• WAP is built on its own lower level communication
  protocol
• Typical deployment of WAP includes a proxy or a
  gateway
• WAP is a complete framework for a mobile
  applications

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WAP Architecture

• Its a client-server Architecture
• Implementation standards
• for client to interpret content
• communication mechanisms between the clients and
  the servers
• additional required features in the server
  (particulary proxy servers)
• Communication functionality between clients and
  server
• Handling of Telephony on the Device
• Push

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Basic Communication Architecture in WAP
Application Server
WAP Proxy / Gateway
WAP Client
HTTP/ HTTPS
WSP,WTP,WTLS,WDP
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WAP UI

• Developing WML pages
• WML Mark-up language rendered by the WAP micro
  browsers
• Advantages over HTML
• WML tag is smaller
• WML is XML compliant
• WML is designed for small monochrome screens
• allows breaking a page into a deck of cards
• allows client-side navigation between the cards
• WML has mark-up tags that allow interacting with
  the telephony
• Disadvantages
• Most content on Internet is in HTML
• Conversion of HTML to WML is not easy process
• WAP 2.0 fixes that using XHTML that is
  well-formed and using XML techniques like XSLs
  to convert XHTML to WML

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WAP Proxies and Gateways

• A server that supports WAP and HTTP
• Difference between the proxy and the gateway
• user can determine will he use proxy

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WAP Gateways (1)

• Features of WAP Gateways
• Security
• Handoff point between WTLS (Wireless Transport
  Layer Security) to external security mechanisms
  (SSL)
• Network Access
• Access point
• Controlled access by Network Provider
• Protocol Conversions
• Converting WSP (Wireless Session Protocol) to
  HTTP

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WAP Gateways (2)

• Caching
• Extremely aggressive caching
• cache expire must be set manually
• reduces the pervasiveness of content
• Preparation of Content and Scripts
• Gateway encodes WML into Compiled WML (WMLC)
• WMLScript must be compiled before being sent to
  client
• Functionality offered through WAP 2.x
• offering model of connectivity that puts
  increasingly less functionality into the proxy

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MMS

• MMS - Multimedia Messaging Services
• WAP MMS is a standard
• Overview
• Presentation
• handled through SMIL (Synchronized Multimedia
  Integration Language)
• Addressing
• two addresses
• address of the MMS Proxy-relay
• address of the recipient user and terminal
• Delivery is possible through variety of
  interfaces.
• These include the following
• MMS proxy-relay
• Standard email interface (supports any email
  protocol)
• Legacy wireless messaging systems

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WAP Push

• Based on Push Access Protocol (PAP)
• Push operation
• WAP push event do the following
• The mobile device connects and registers to
  Master Pull Proxy
• Application Server establishes a connection to
  PPG through PAP protocol
• The content being pushed can be a multipart
  document following the MIME format
• The user agent profile is accessed.
• The message is then sent to PPG
• The devices receives the message

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Security

• WAP does not have application authorization
• Offers guaranteed authentication of user devices
• Offers guaranteed integrity of transactions

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Symbian EPOC

• Symbian OS 7.0 supportsMMS, HTTP, SyncML, SMS,
  Mobile IP, IrDA, and Bluetooth
• It has free SDK (supported languages C and
  Java)
• Designed more as a PDA OS

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Publishing Frameworks

• Presenting content in several different formats
• Matching the type of document requested with the
  type of document available (or one that may need
  to be generated at run time)
• Modularized infrastructure that separates the
  various components of the framework, the
  processing components, and the content

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Publishing Frameworks

• Examples
• Apaches Cocoon
• best known publishing framework today
• written in Java, supports ASP, Java and XSL (and
  many other)
• IBMs Wireless Transcoding Publisher
• They treat the user interface problems presented
  by the following
• Proliferation of mobile devices
• Localized and Internationalized user interfaces
• Selection of segments of multichannel content
• Selection and composition of content based on
  device information

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Cocoon

• Open-source widely accepted
• Got his name from the movie
• Cocoons Architecture aim to separate
• content
• style (the formatting of content)
• logic (how content is generated or chosen)
• management of content (creating content)

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Cocoons Architecture
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Generators

• Take static/dynamic content
• Generate XML in the form of SAX events
• There are series of generators
• File generator
• Server pages generator
• JSP generator
• Request generator

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Transformers

• Xalan XSL transformation engine
• XSLs are not platform dependent or language
  dependent

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Serializer

• Responsible for publishing to the client through
  HTTP response
• FOPSerializer (Converts HTML to PDF)
• SVG Serializer

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IBM Wireless Transcoding Publisher

• Focusing on product, IBM Wireless Everyplace
  Suite
• Integrated environment with IBMs Websphere
  Application Server
• Our focus is on pervasive and mobile aspects of
  this suite and comparison with Cocoon

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Overview of IBM Everyplace Suite

• Addresses issues like
• wireless connectivity
• content management for wireless clients
• wireless security
• provisioning and device management

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Comparison of the WTP and Cocoon

• WTP offers better functionality in converting
  HTML to any other markup language than Cocoon
• WTP offers custom transformers that convert
  variety of image formats
• WTP offers a set of WAP devices that allow very
  simple publishing of HTML and XML content to
  WML-enabled devices
• Very rich set of tools for developers

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Other Tools

• Asynchronous Messaging Systems
• UML Tools

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XML for Mobile Computing
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XML and Mobile Applications

• Mobile applications should understand and be able
  to manipulate XML content
• Mobile applications use XML to facilitate their
  implementations

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Key XML Technologies for Mobile Computing

• XHTML
• VXML
• designed for voice user interfaces
• allows specification of a command-based voice
  dialog through a markup language
• WML
• XForms
• CCXML
• XML Pipeline
• WBXML
• SSML
• RDF

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CCXML

• Call Control Extensible
• Markup Language
• Application of XML for managing voice calls
• It focuses on routing the calls and connecting
  calls (in contrast to VXML)
• It is based on Java Telephony APIs (JTAPI)

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XML Pipeline

• It specifies how to process various XML
  resources
• It can be thought in two different contexts
• It specifies the flow of processing instructions
  that are applied to one or more given documents
  residing on the host
• It specifies the flow of processing instructions
  that are applied to a variety of XML documents,
  residing at a variety of hosts

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Sample XML Pipeline Document

• lt?xml version1.0gt
• ltpipeline xmlnshttp//www.w3.org/2002/02/xml-pip
  eline xmlbasehttp//www.cienecs.com/Examples/X
  MLPipelinegt
• ltparam nametarget selectresult /gt
• lt! This section defines the processes and links
  them to their definitions (typically some hint to
  the controller on where and how to start off the
  processes). We chose Java for our examples, so
  the definition is in terms of Java classes. --!gt
• ltprocessdef nameselector definitioncom.cienec
  s.mobile.http.get_content_selector /gt
• ltprocessdef name selector_content
  definitioncom.cienecs.mobile.http.get_content_ge
  nerator /gt
• ltprocessdef nameauthenticator
  definitioncom.cienecs.mobile.security.authentica
  tor (username) (password) /gt
• ltprocessdef nametransformer definitioncom.cie
  necs.mobile.transformer.xslt /gt
• lt! For our example, we chose a set of processes
  that select some content based on the users
  request. SO, the first thing to do is to find the
  content that the user requested. --!gt
• ltprocess id3 typeselected_content gt
• ltinput nameuti_param_1 labelcontent_finder_par
  am_1 /gt
• ltinput nameuri_param_2 labelcontent_finder_pa
  ram_2 /gt
• ltoutput namecresult labelgeneric_content_URI
  /gt
• lt/processgt

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Sample XML Pipeline Document

• lt! For our example, we want to transform the
  content based on the device that the user is
  using. SO, we need to fire off a process that
  finds out the users device type.. --!gt
• ltprocess id1 typeselector gt
• ltinput namedeviceId labelunique_device_id
  /gt
• ltinput nameccpp_header_string
  labelccpp_header_string /gt
• ltoutput nameresult labeldevice_type /gt
• lt/processgt
• lt! Now, based on the users device type and the
  selected content, we can find the right type of
  transformer and transform the content properly.
  --!gt
• ltprocess id2 typetransformer gt
• ltinput namedevice_type labeldevice_type /gt
• ltinput namegeneric_specific_URI
  labelgeneric_content_URI /gt
• ltinput nameauthenticated labelauthenticated
  /gt
• ltoutput namedevice_specific_content
  labeldevice_specific_content /gt
• lt/processgt
• lt/pipelinegt

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XML Pipeline

• Recognize type of processes
• Constructive processes produce new information
• Augmenting processes add new types (definitions)
  of information
• Inspection processes look at the content of a
  document
• Extraction processes copy a part of the document
  that they look into
• Packaging processes are distributed processes
  that address the processing of distributed
  resources

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WBXML

• WAP Binary Extensible Markup Language
• Defines a way to represent XML in 0s and 1s
  instead of text
• KXML (parse WBXML)

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SSML

• Synthetic Speech Markup Language
• It is used for the infrastructure of the voice
  user interface

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RDF

• Resource Description Framework
• Created specifically
• to allow discovery of various resources
• indexing them
• creation of resources that are made up of other
  RDF resources by simply nesting the RDF
  descriptions
• RDF is part of Semantic Web.

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Thank You for Your Attention