5 Dataflow Diagram

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    Reference:http://s3.amazonaws.com/ppt-download/dataflowdiagram090322155640phpapp01

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    Data Flow Diagrams (DFDs)

    Data fow diagram (DFD) is a picture o the

    movement o data between externalentities and the processes and data stores

    within a system

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    DFD Symbols

    Process

    Data Flow

    Data Store

    Source/Sink (External Entity)

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    Process

    Wor or actions perormed on data (inside the

    system)

    !abels should be verb phrases

    "eceives input data and produces output

    #ust be numbered

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    "ule $% Process&an have more than one outgoing data fow or

    more than one incoming data fow

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    "ule '% Process

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    Process% &orrectncorrect?

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    Data Flow

    s a path or data to move rom one part o the S to

    another

    *rrows depicting movement o data

    &an represent fow between process and data store

    by two separate arrows

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    Data Flow% &orrectncorrect?

    +o Data Storeto another

    withoutprocess

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    Data Store

    s used in a DFD to represent data that the

    system stores

    !abels should be noun phrases

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    "ule% Data Store#ust have at least one incoming and one outgoing data

    fow

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    Data Store% &orrectncorrect?

    #usthaveinput

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    SourceSin (,xternal ,ntity)

    ,xternal entity that is origin or destination o data-

    !ie a department. outside organi/ation. other S.

    or person

    !abels should be noun phrases Source 0 ,ntity that supplies data to the system

    Sin 0 ,ntity that receives data rom the system

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    "ule% SourceSin

    #ust be connected to a process by a data fow

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    SourceSin% &orrectncorrect?

    XX

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    "ules or 1sing DFD Symbols

    Data Flow 2hat &onnects

    YES NO

    A process to another process

    A process to an external entity

    A process to a data store

    An external entity to another external entity

    An external entity to a data store

    A data store to another data store

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    List the errors of this DFD

    X3 X5

    X4

    X2

    X1

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    &ontext Diagram

    2op3level view o S

    Shows the system boundaries. external entities

    that interact with the system. and ma4or

    inormation fows between entities and the system-

    ,xample%5rder system that a company uses to

    enter orders and apply payments against a

    customer6s balance

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    Context Diagram

    of Order System

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    !evel37 DFD

    Shows the system6s ma4or processes. data fows.

    and data stores at a high level o abstraction

    When the &ontext Diagram is expanded into DFD

    level37. all the connections that fow into and out

    o process 7 needs to be retained-

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    Leel!" DFD of

    Order System

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    !ower3!evel Diagrams

    *n iterative process o breaing a system

    description down into 8ner and 8ner detail

    1ses a series o increasingly detailed DFDs to

    describe an S