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PowerPoint PowerPoint Presentation Transcript

  • .NET Mobile Application Development The Challenge of Mobility
  • Introduction
    • Many mobile applications are clients in larger distributed systems
    • In the last session we considered
      • Characteristics of distributed applications
    • In this session we will look at
      • Mobile devices
      • Mobile devices as clients in distributed applications
      • Particular challenges of mobile devices
  • The Mobile Revolution
    • Computers no longer tied to the desktop
    • Devices are increasingly mobile and wirelessly enabled
      • Personal Digital Assistants (PDA’s)
      • Mobile phones
      • Smart phones
    • Mobile device usage is common
      • 75% of UK population own a mobile phone
    • Mobile devices will increasingly be used as clients in distributed applications
      • Developers must address peculiar mobile device characteristics
  • Pervasive Computing
    • A vision of 21 st Century computing
      • Available any time, any place, in any device
    • Pervasive computing
      • ‘ computing power freed from the desktop – embedded in wireless handheld devices, automobiles, home appliances and commercial tools-of-the-trade. In the enterprise it extends timely business data to workers in the field… In our personal lives, it expands our freedom to exchange information anytime, anywhere ’ IBM
    • Devices are becoming
      • more mobile
      • more embedded
      • casually connected to a ubiquitous network with wired core and wireless edges
  • Visions of Pervasive Computing
    • Users are predominantly mobile
    • Computing is mobile and wirelessly connected
    • Unmanaged, dynamic network environment
    • Devices/appliances containing embedded computing are clients in this distributed environment
    • Business domain / distributed wireless office is an ultimate goal
      • Mobile phones, PDA’s, laptops, corporate servers seamlessly integrated in wireless network environment
      • Workers can access info and resources needed to do their job regardless of their location
  • Mobile Devices
    • Many different mobile devices
      • Laptops/Tablet PC’s
        • Essentially same as standard desktop PC’s
      • Personal Digital Assistant’s
        • Pocket-sized handheld computer with
          • Calendar, contact management, note taking, Web browser & media player apps
          • Pen interface
          • 802.11/Bluetooth/GPRS connectivity
      • Mobile Phones
        • Smaller than PDA; primarily a telephone with extra functions
        • Current devices are 2.5G digital/GSM
        • 3G devices becoming more common
      • Smart phones
        • Hybrid between mobile phone and PDA with mobile phone form factor
  • PDA Characteristics
    • Typical spec
      • CPU: up to 400 MHz RISC processors
      • Memory: 8 – 128MB RAM for programs and file store
      • Screen: 6cm x 8cm
      • Stylus for input with handwriting recognition
  • Mobile Phones
    • Evolved over three generations
      • 1 st generation – analogue phones
      • 2 nd generation
        • Voice centric, GSM digital phones
        • Low bandwidth data access via SMS, WAP
      • 2.5 generation – most current phones
        • Higher data rates via GPRS – EMS, MMS
        • Effectively always on network connection
        • Personal management apps – calendar, contacts
      • 3 rd generation
        • Goal is complete personal communication system
        • Broad bandwidth data connections
        • Streaming multimedia, video telephony and full Internet access supported
    • Predictions suggest that number of mobile phones connected to Internet will exceed number of Internet connected PC’s by 2007
  • Mobile Phone Characteristics
    • Typical spec
      • CPU: < 200 MHz RISC processors
      • Memory: < 32MB RAM for programs and file store
      • Screen: Typically 3.5cm x 4.5cm or less
      • Input: via numeric keypad
    • Must behave as advanced (not thin) client and smoothly transition between being networked and self-sufficient device
  • Common Characteristics
    • Physical
      • Small and light enough to be carried about the person => size & screen resolution constraints
    • Power management
      • Battery powered
        • Must be designed to minimize power consumption, maximize battery life
      • Always on
        • Devices never completely powered down
        • Boot sequence must be short
      • Processor speeds/power consumption increased greatly over recent years
        • Battery technology improvements have not kept pace
  • Common Characteristics…
    • Memory and storage
      • Limited memory capacity (compared to PC’s)
      • Slower than desktop memory
      • Memory used for file storage and running programs
    • Network connectivity
      • Intermittent connection
        • Devices do not have permanent connection
        • Need to cope gracefully with service interruptions and disconnected operation
      • Variety of networks
        • Different networks encountered at different times
        • Must manage and use these seamlessly
    • Security
      • Device often contain valuable/sensitive data – personal and business (e.g. connection to corporate gateway)
      • Small devices easily lost or stolen
      • Good range of security and authentication features required (e.g. biometrics)
  • Common Characteristics…
    • Telephony
      • Many mobile devices offer voice telephony support
      • OS’s must provide comprehensive telephony services and make these available to other devices
    • Processors
      • Mostly ARM-based
      • Similar architecture to desktop CPU’s
      • Lack some features of general purpose desktop processors due to competing constraints of size, power consumption and hardware features
    • Operating Systems
      • Specialized OS’s required targeted at custom chipsets used
      • Trimmed down desktop OS’s not appropriate
      • Three key OS’s used in majority of mobile devices
        • PalmOS – PDA’s
        • Symbian – Mainly phones
        • Windows CE .NET – Pocket PC (PDA) and SmartPhone (Mobile phones)
  • Mobile Services
    • Each mobile platform provides fundamental set of services
      • PDA’s
        • Internet access, e-mail, personal information management (PIM), office apps
        • Configurable by owner
      • SmartPhones
        • As PDA’s, plus voice telephony and messaging (SMS/EMS/MMS)
      • Mobile phones
        • Voice telephony, WAP, SMS/MMS, limited PIM
        • Configuration fixed by manufacturer/network provider
        • User personalisation possible
  • Location Awareness
    • Fundamental feature of many mobile devices
    • Legal requirement for mobile phones in UK/USA
      • Location determination for calls to emergency services
    • Commercial applications also leverage this location awareness
      • Tracking and logistics
        • Embedded devices in delivery trucks to monitor operations and deliveries
        • Automobile remote diagnostics and telemetry
      • Location-based information and data
        • Services provided to mobile user based on geographical location (e.g. maps, nearest chemist, etc)
    • Location awareness becoming increasingly important
      • Incubating new business models and applications (e.g. smart environments)
  • Mobile Applications
    • Mobile applications are inherently distributed client-server apps
    • Two models of interaction
      • Pull products / services
        • Traditional model – most desktop apps are pull-based
        • User makes explicit request for info/service (e.g. Web browser)
      • Push products / services
        • Automatic - no explicit request required
        • Data sent to user based on known user preferences
        • Fit well with mobile devices due to availability of messaging services, etc (e.g. delivery of stock quotes or sports results via SMS)
        • Innovative services result from combining with location-awareness
    • Innovative uses of mobile technology and mobile applications are emerging
      • e.g. wireless vending machines, information kiosks, wearable computing
    • In this session we have discussed
      • Common mobile devices
      • Mobile device characteristics and limitations
      • Mobile applications and services
    • In the next session we will begin to consider the software technologies used in implementing mobile applications
    Summary
  • Reading and Resources
    • Reading
    • Uwe Hansmann et al., Pervasive Computing Handbook , Springer-Verlag, 2001
    • Geoffrey Elliot and Nigel Phillips, Mobile Commerce and Wireless Computing Systems , Addison-Wesley, 2004
    • Deitel, Deitel, Nieto & Steinbuhler, Wireless Internet and Mobile Business – How to Program, Prentice Hall, 2002