Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols...
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![Page 1: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/1.jpg)
Data Flow Diagrams
Objectives:• To define what is meant by structured analysis• To define the symbols used in a Data Flow
Diagram (DFD)• To draw a context diagram (Level 0 DFD) for a
given scenario• To refine a DFD to a more detailed (lower-level)
view
![Page 2: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/2.jpg)
Structured analysis
•A widely-used top-down method for defining system inputs, processes and outputs. •It shows how information flows through a system, using several diagrams showing progressively more and more detail at each level. •The primary tool of structured analysis is the Data Flow Diagram (DFD).
![Page 3: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/3.jpg)
Data Flow DiagramsThe following four symbols are used in data flow diagrams:
External entity
Process
Data store
Data flow
![Page 4: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/4.jpg)
Data flow diagram of a travel agent booking system
CustomerTravel-query
Booking confirmation
Available flights
Booking
flightsBook flight
![Page 5: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/5.jpg)
Data flow diagram of part of an order processing system
Customer
Order
Invoice
Available stock stock
Process order
Out-of-stock noticeUnfilled order
backorders
Warehouse
Despatch note
![Page 6: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/6.jpg)
Context diagramsa top-level DFD shows the least amount of detail and is known as a Level 0 DFD or context diagram.
Customer
Order
Invoice
Process orderOut-of-stock notice
Picking ListWarehouse
Order rejection notice
![Page 7: Data Flow Diagrams Objectives: To define what is meant by structured analysis To define the symbols used in a Data Flow Diagram (DFD) To draw a context.](https://reader036.fdocuments.us/reader036/viewer/2022072013/56649e4d5503460f94b438fb/html5/thumbnails/7.jpg)
• Level 0 or context diagram shows a system as a single process with inputs and outputs flowing to or from external entities.
• Level 1 DFD will split up that single process into subsystems and show more detail about the data flows and data stores.
• Level 2 DFD may decompose a single subsystem even further.