Create D F D by toVV2OW

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									Creating Data Flow Diagrams
          Data Flow Diagrams Symbols
DeMarco & Yourdon    System Analysis and Design
                     System – a group of interrelated procedures
      Source/        used for a business function, with an
       Sink          identifiable boundary, working together for
                     some purpose.
                     Analysis – separation of a whole into its
                     component parts
         0.0
       Process       Design – to create, fashion, execute, or
                     construct according to plan

                     Physical Data Flow Diagrams – show how
    DATA STORE
                     the current system flows

   Data Flow Lines
                     Logical Data Flow Diagrams – show the data
                     flow, structure, and requirements of a new
                     system
          Data Flow Diagrams Symbols
DeMarco & Yourdon
                     Source/Sink – help to establish the
      Source/        boundaries of the system. A source identifies
       Sink          the origin of data inflow to the system. A sink
                     identifies the outflow of a system, many times
                     as information.
                     Sometimes referred to an entity, a source
         0.0         may be a customer, vendor, employee, or
       Process
                     even another system. A single entity can be
                     both a source and a sink.

    DATA STORE


   Data Flow Lines
          Data Flow Diagrams Symbols
DeMarco & Yourdon
                     Processes – are the activities (manual and
      Source/        automated) that transform the inputs,
       Sink          transport data from process to process,
                     stores the data, and produce the outputs of a
                     system.
                     Processes are used on every DFD starting
         0.0         with an over all process on the context level
       Process
                     diagram, the system. The system is then
                     decomposed until a primitive level is
                     obtained. The primitive level is the point in
    DATA STORE       which the relevant activities of a process are
                     identified.

   Data Flow Lines
          Data Flow Diagrams Symbols
DeMarco & Yourdon
                     Data Store – is the resting place of the data
      Source/        in a system. A data store can be in the form
       Sink          of paper, a disk file or any other media.
                     Normally the word ‘data’ does not appear in
                     the title of a data store. Some examples of
                     data stores are Customer Order, Payment,
         0.0         Invoice, Time Card……
       Process




   DATA STORE


   Data Flow Lines
          Data Flow Diagrams Symbols
DeMarco & Yourdon
                     Data Flow – is the data in motion. Data can
      Source/        move from the outside (source) into a
       Sink          process. Once the inside of a system data
                     must flow from place to place through a
                     process, the flow lines show this movement.
                     The lines are labeled to provide clarity and
         0.0         meaning to the data moving through the
       Process
                     system.


   DATA STORE


   Data Flow Lines
            Data Flow Diagrams Levels
DeMarco & Yourdon
                                         Context Level DFD
      Source/         Source/ Sink
                                        Data Flow        0.0
                                                                                  Source/ Sink
                                                       Process
       Sink                                                       Data Flow
                                        Data Flow


                                                   Level 0 DFD
         0.0
                                                        1.0
       Process                                        Process
                                     Data Flow                       Data Flow
                                                     Data Flow


    DATA STORE                                          2.0
                     Source/ Sink                                                Source/ Sink
                                                      Process
                                       Data Flow                 Data Flow

                                                     Data Flow
   Data Flow Lines
                                                        3.0
                                                      Process        Data Flow
            Data Flow Diagrams Levels
DeMarco & Yourdon
                      Source      Level 1 DFD (and on)
                     Data Flow
      Source/
       Sink

                                      1.1
                                                        DATA STORE
                                    Process

         0.0
       Process          Source
                                                1.2
                      Data Flow               Process



   DATA STORE


                                                           Data Flow
   Data Flow Lines
                                                             Sink
                     Data Flow Diagrams Levels
                                                                       Prepared by: yourname
                         Project Name                                       Date: 01/01/2002                                                                     Project Name
                                                                                                                                                                                                            Prepared by: yourname
                                                                                                                                                                                                                 Date: 01/01/2002
                   Context Level DFD                                                                                                                              Level 1 DFD

                                                                                                              Data Flow




                                                                                                                                   1.1
                                                                                                                                                                              DATA STORE
                                                                                                                                 Process


                                                                                                                                                                                                                Prepared by: yourname
                  Data Flow           0.0
                                                                                                                                                                      Project Name                                   Date: 01/01/2002
Source/ Sink                                                 Source/ Sink                                                                                     1.2
                                    Process                                                                    Data Flow
                                              Data Flow                                                                                                     Process
                  Data Flow
                                                                                                                                                                      Level 1 DFD

                                                                                      Prepared by: yourname
                                      Project Name                                                                Data Flow
                                                                                           Date: 01/01/2002

                                          Level 0 DFD                                                                                                                               Data Flow

                                                                                                                                          1.1
                                                                                                                                                                                    DATA STORE
                                                                                                                                        Process

                                                                                                                                                                                                                       Prepared by: yourname
                                                                                                                                                                               Project Name                                 Date: 01/01/2002

                                                                                                                                                                  1.2
                                                 1.0                                                               Data Flow                                    Process         Level 1 DFD
                                               Process
                              Data Flow                       Data Flow
                                              Data Flow
                                                                                                                           Data Flow

                                                 2.0
               Source/ Sink                                                 Source/ Sink
                                Data Flow
                                               Process
                                                          Data Flow                                                                                                                     Data Flow

                                                                                                                                                    1.1
                                              Data Flow                                                                                                                                   DATA STORE
                                                                                                                                                  Process


                                                 3.0
                                               Process        Data Flow
                                                                                                                                                                            1.2
                                                                                                                            Data Flow                                     Process




                                                                                                                                                                                                Data Flow
            Creating Data Flow Diagrams
Steps:
   1. Create a list of activities
   2. Construct Context Level DFD
      (identifies sources and sink)
   3. Construct Level 0 DFD
      (identifies manageable sub process )
   4. Construct Level 1- n DFD
      (identifies actual data flows and data stores )
Creating Data Flow Diagrams
 Lemonade Stand Example
           Creating Data Flow Diagrams
       Example                Steps:
The operations of a simple    1. Create a list of activities
lemonade stand will be used
                              2. Construct Context Level DFD
to demonstrate the creation
                                 (identifies sources and sink)
of dataflow diagrams.
                              3. Construct Level 0 DFD
                                 (identifies manageable sub processes )
                              4. Construct Level 1- n DFD
                                 (identifies actual data flows and data stores )
            Creating Data Flow Diagrams
       Example                  1. Create a list of activities

Think through the activities
that take place at a lemonade
stand.
                                     Customer Order
                                     Serve Product
                                     Collect Payment
                                     Produce Product
                                     Store Product
            Creating Data Flow Diagrams
       Example                 1. Create a list of activities

Also think of the additional
activities needed to support
the basic activities.
                                    Customer Order
                                    Serve Product
                                    Collect Payment
                                    Produce Product
                                    Store Product
                                    Order Raw Materials
                                    Pay for Raw Materials
                                    Pay for Labor
            Creating Data Flow Diagrams
       Example               1. Create a list of activities

Group these activities in
some logical fashion,
possibly functional areas.
                                  Customer Order
                                  Serve Product
                                  Collect Payment

                                  Produce Product
                                  Store Product

                                  Order Raw Materials
                                  Pay for Raw Materials

                                  Pay for Labor
            Creating Data Flow Diagrams
       Example               2. Construct Context Level DFD
                                (identifies sources and sink)
Create a context level
diagram identifying the
                                            Context Level DFD
sources and sinks (users).
                                                                       Sales Forecast
                                             Order            0.0
                              CUSTOMER                     Lemonade Production Schedule EMPLOYEE
Customer Order                           Product Served     System        Pay
Serve Product                               Payment                      Time Worked
Collect Payment                                  Received Goods
                                                    Payment
                                                                    Purchase Order
Produce Product
Store Product                                              VENDOR


Order Raw Materials
Pay for Raw Materials

Pay for Labor
            Creating Data Flow Diagrams
       Example               3. Construct Level 0 DFD
Create a level 0 diagram        (identifies manageable sub processes )
identifying the logical                              Level 0 DFD
subsystems that may exist.
                                                              1.0
                                                              Sale
                                    Customer Order                                Sales Forecast
Customer Order
                                                        Product Ordered
Serve Product
                                                 Payment
Collect Payment                                                2.0             Production
                              CUSTOMER                                                        EMPLOYEE
                                                            Production          Schedule
                                           Product Served
Produce Product
                                         Received Goods           Inventory
Store Product
                                                              3.0
                               VENDOR                       Procure-        Order
                                           Purchase Order
Order Raw Materials                                          ment          Decisions
Pay for Raw Materials                      Payment
                                                                         Pay         Time Worked

Pay for Labor                                                 4.0
                                                             Payroll
           Creating Data Flow Diagrams
       Example                4. Construct Level 1- n DFD
Create a level 1                 (identifies actual data flows and data stores )
decomposing the processes                               Level 1 DFD
in level 0 and identifying
                                                           CUSTOMER
data stores.
                              Customer Order
                                                             ORDER
                                                                           Request for Forecast
Customer Order
                                                1.1
Serve Product                                  Record
Collect Payment                                Order                       1.3
                                                                         Produce
                                                         Severed Order    Sales
Produce Product              Payment                                     Forecast
                                                                                     Sales Forecast
Store Product
                                             1.2
                                           Receive          PAYMENT
                                           Payment
Order Raw Materials
Pay for Raw Materials

Pay for Labor
           Creating Data Flow Diagrams
       Example               4. Construct Level 1 (continued)
Create a level 1
decomposing the processes                              Level 1 DFD
in level 0 and identifying
                             Product Order
data stores.
                                                              ORDER
Customer Order                                 2.1
                                              Serve       Quantity Severed
Serve Product                                Product
Collect Payment                                                 RAW
                             Production
                                                              MATERIALS
                              Schedule
Produce Product                                2.2
Store Product                                Produce    Quantity Used
                                             Product

                                                            INVENTORTY
Order Raw Materials                Production Data
Pay for Raw Materials
                                               2.3       Quantity Produced &
                                              Store      Location Stored
Pay for Labor                                Product
           Creating Data Flow Diagrams
       Example               4. Construct Level 1 (continued)
Create a level 1
decomposing the processes                                 Level 1 DFD
in level 0 and identifying    Order Decision
                                                                         PURCHASE
data stores.                                      3.1                     ORDER
                                               Produce
                                               Purchase
Customer Order                                  Order         Quantity On-Hand
Serve Product                                                               RAW
                                                           Quantity       MATERIALS
Collect Payment                Received                   Received
                                Goods
                                                  3.2
Produce Product                                Receive
                                                Items
Store Product                                                               RECEIVED
                                                                             ITEMS
                                          Payment Approval
Order Raw Materials
                                                                             VENDOR
Pay for Raw Materials                           3.3
                                                Pay
                                               Vendor
Pay for Labor
                                 Payment
           Creating Data Flow Diagrams
       Example               4. Construct Level 1 (continued)
Create a level 1
decomposing the processes                                  Level 1 DFD
in level 0 and identifying   Time Worked

data stores.                                     4.1                 TIME CARDS
                                               Record
                                                Time
Customer Order                                 Worked         Employee ID
Serve Product                                                          EMPLOYEE
Collect Payment
                             Payroll Request
                                                  4.2
                                                                   Unpaid time cards
Produce Product                                Calculate
                                                Payroll
Store Product                                                               PAYROLL

                                          Payment Approval
Order Raw Materials
                                                 4.3
Pay for Raw Materials                            Pay
                                               Employe
                                                  e                  PAYMENTS
Pay for Labor
                                Payment
               Process Decomposition
                                   1.1        1.2
                      1.0
                                  Record    Receive
                      Sale
                                  Order     Payment




                                    2.1       2.2         2.3
                       2.0
                                   Serve    Produce      Store
                    Production
                                  Product   Product     Product


       0.0
    Lemonade
     System
                                    3.1
                       3.0                     3.2       3.3
                                 Produce
                     Procure-               Receive      Pay
                                 Purchase
                      ment                   Items      Vendor
                                  Order




                                    4.1                   4.3
                                               4.2
                      4.0         Record                  Pay
                                            Calculate
                     Payroll       Time                 Employe
                                             Payroll
                                  Worked                   e



Context Level      Level 0       Level 1
Creating Data Flow Diagrams
 Lemonade Stand Example
           END

								
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