Data Flow Diagram for Library System by kmz12675

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									                                                                                         Data Flow Diagrams
                                                                   • Conceptual model of the system
                Data Flow Diagrams                                 • Graphical technique for depicting information flow
                                                                     and transformations that are applied as data moves
                                                                     from input to output
                            and                                    • Components include
                                                                       –   Data source
                                                                       –   Data sink
                     Data Dictionaries                                 –   Data stores
                                                                       –   Transformations or processes
                                                                       –   Flow of data
                                                                   • Do not include flow of control



Data Flow Diagrams                               CS172 2005       Data Flow Diagrams                                                                                 CS172 2005
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                                                                                              A Library Example
         Data Flow Diagram Notation                                                                 Book                                      Book request
                                                                                     Shelves                                                  by the user

   • Rectangles - for sources and sinks                                                                                            Request
                                                                                        Author

                                                                                                                                             Book           Book
                                                                             List of Authors
   • Circles - for transformations and processes                                                                   Get a book                               reception


                                                                                                      Title
                                                                                                                                         Book title;
                                                                                                                                         user name
                                                                               List of titles
   • Parallel lines - for data stores
                                                                                                     Title                                   List of books borrowed
                                                                                                                  Search by
                                                                                                                  topics
   • Arrows - for data flows                                                 List of topics
                                                                                                 Topic
                                                                                                                                Titles          Display of
                                                                                                                Topic
                                                                                                                                                the list of titles


                                                                                                Topic request
                                                                                                by the user
Data Flow Diagrams                               CS172 2005       Data Flow Diagrams                                                                                 CS172 2005
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                                                                      Data Dictionary Entry for Request
                     Data Dictionary
                                                                  Name:                               Request
   • One entry for each label on a data flow                      Where Used:                         Get a book
     diagram arc                                                  Purpose:                            Request passes the information
   • Each entry includes                                                                              necessary to request that a book
       – Name of the data item                                                                        be checked out of the library
       – Attributes (such as where it is used)                    Derived From:                       Book request by the user
       – Its purpose                                              Subitems:                           Title
       – Where it is derived from                                                                     Author
       – Its subitems                                                                                 Book
       – Any appropriate notes                                    Notes:                              Both the title and the author may
                                                                                                      not be necessary
Data Flow Diagrams                               CS172 2005       Data Flow Diagrams                                                                                 CS172 2005
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                                                                                                                                                                                      1
                                                                                                                                         Refinement of
                                                                                                                                         “Get a book”
   Data Flow Diagram Decomposition
                                                                                                                      Book

   • Hierarchical decomposition
                                                                                                       Shelves
   • Inner workings of functional nodes are                                                                                  Author                                                  Get           Book
     expressed in data flow diagrams                                                                                                                                                 the book
                                                                                                    List of Authors
   • Still no decision structures nor algorithms                                                                                           Find
                                                                                                                                                                     <shelf#, book#>
                                                                                                                                                                                                                 Book
                                                                                                                                                                                                                 reception
                                                                                                                          Title
   • Well developed data flow diagrams permit                                                                                              book
                                                                                                                                           position
     the reader to determine the overall operation                                                    List of titles                                                         List of books borrowed

     of the system with little or no supporting                                                                                      Request
                                                                                                                                                                                  Book title;
     narrative                                                                                                                                                                    user name
                                                                                                               Book request
                                                                                                               by the user


Data Flow Diagrams                                                           CS172 2005       Data Flow Diagrams                                                                                           CS172 2005
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                                                HMO                                                       Decomposed HMO System
                                                                                                                                                                            Process
                                                                                                                                                                         Prescription
                                                                                                                                                      Prescription                        Medication

                                                                                                                       Medical
                                                                                                                       Experience
                       Medical
                                                             Medication                                                and Knowledge                                     Symptoms
                       Experience
                                                                                                          Physician                        Physical                                                    Patient
                       and Knowledge             Symptoms
                                                                                                                                             Exam
           Physician                     HMO                              Patient
                                                             Diagnosis                                                                                                   Diagnosis
                                       System
                                                                Bill
                                                                                                             Pat Update

                                                                                                                            Pat Record            List of
                                                  Figure 1                                                                                        Tests and
                                                                                                                                                                                            Bill
                                                                                                                 Patient                          Services
                                                                                                                 Records                                                  Accounting
                                                                                                                                                                            System

                                                                                                                          Medical Reference
                                                                                                                                                      Acc Update
                                                                                                                          Books and Journals

                                                                                                                                                                     Acc Record

                                                                                                                                                        Accounting
                                                                                                                                                        Records


                                                                                                                                                        Figure 2


Data Flow Diagrams                                                           CS172 2005       Data Flow Diagrams                                                                                           CS172 2005
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