Chapter 7 Notes Use Case & DFDs

Chapter 7 Notes Use Case & DFDs - Chapter 7 Use Case...

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1 Chapter 7 2 Basic Symbols
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2 3 DFDs - Naming Conventions ± External Entity ± Name with a noun, describing that entity (Customer, Bank, Inventory Control System ) ± Processes ± Assign the name of the whole system when naming a high-level process - (In Context diagram- Airline Reservation System) ± To name a major subsystem attach the word subsystem to the name (In DFD 0- Customer Inquiry Subsystem) ± Use the form verb-adjective-noun for detailed processes (Validate Customer Request, Prepare Management Reports) ± Data Flows ± Name with a noun that describes the data moving through the system (New Customer, Customer Data) ± Data Stores ± Name with a noun, describing the data (Customer Master) 4 Context Diagram ± Simple representation of the entire system under investigation. ± First DFD in every business process ± Shows the context into which the business process fits ± The interface between the system under investigation and the external entities with which it communicates. ± Shows all the external entities that receive information from or contribute information to the system ± Shows the overall business process as just one process (process 0) ± The system under investigation is represented as a single process, connected to external entities by data flows and resource flows. ± This single process system is placed in the center of the page and the entities around the perimeter of the page ± Help in clarifying the precise scope of the analysis.
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3 5 Example: Context Diagram- Grading System Entities: Student Record System, Student, Instructor Student Record System Supply data through CLASS ROSTER data flow and receive data through FINAL GRADE data flow Student Supply data through SUBMITTED WORK data flow and receive data through GRADED WORK data flow Instructor Supply data through GRADING PARAMETERS data flow and receive data through GRADED WORK data flow 6 Context Level Diagram
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4 7 Example: Context Diagram - Order System 8 Diagram 0 ± Context diagram: ± Depicts the overall business process for a generic system. ± Further analysis necessary in order to identify the major functional areas. ± Diagram 0: ± Explosion of the context level diagram. ± Depicts the main functional areas of the system under investigation. ± Identifies the major business processes and data flows at a high level
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Chapter 7 Notes Use Case & DFDs - Chapter 7 Use Case...

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