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  • 当前位置:文档库 > Introduction to Mobile Computing

    Introduction to Mobile Computing

    Introduction to Mobile Computing

    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

    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

    Introduction to Mobile Computing

    Mobile Development

    Frameworks and Tools ?Fully Centralized

    Frameworks and Tools

    ?N-Tier Client-Server

    Frameworks and Tools

    Tools

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

    Tools Applies:

    ?QOS

    ?Limiter power supply

    ?Active transactions

    ?Location awareness

    Do not apply:

    ?Platform proliferation

    ?Limited device capabilities ?Support for variety of user interfaces

    Examples

    ?Call centers

    ?Battlefield systems

    ?Grocery store

    N-Tier Client-Server Framework

    and Tools

    ?N-Tier-Any N umber of Tiers–No Limits

    ?3-Tier

    –Client (User Agent)

    –Application Server

    –Database

    Basic problems

    ?Code portability

    ?Mobility

    Needs

    ?Layer of Software ?Performance

    and system requirements

    Selection of the Frameworks and

    Tools

    ?Thin-Client Wireless Client-Server

    ?Thick-Client Wireless Client-Server

    ?Stand-alone Applications

    ?Browser that loads markup code (Web-model)?No concern about environment

    ?Server-side structure

    ?Example: WAP with his WML

    ?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

    Difficulties???

    ?Restricted resources ?Deployment and provision problem –Operating system or virtual machine

    –Programming environment

    Introduction to Mobile Computing

    Examples

    ?Operating system

    –Windows CE

    –Symbian

    ?Virtual Machine

    –J2ME

    Stand-alone Applications ?They do not need

    networking components

    ?Needs of synchronization

    with some external system

    periodically

    Some products Connectivity

    Platform Stand-alone

    Networked

    Wired Wireless

    Mobile Platforms

    W AP Symbian

    BREW

    Java

    .NET

    JAVA -features

    ?Object oriented language

    ?Complete code mobility

    ?Weak mobile agent ability

    ?It is a platform