SAD 1 : Assignment 9

Data Flow Diagram

- According to Scott W. Ambler, Data Flow Diagrams (DFDs) show the flow of data from external entities into the system, showed how the data moved from one process to another, as well as its logical storage.

Data Flow Diagramming definitions:

• Context Diagram - A data flow diagram (DFD) of the scope of an organizational system that shows the system boundaries, external entities that interact with the system and the major information flows between the entities and the system

• Level-O Diagram- A data flow diagram (DFD) that represents a system’s major processes, data flows and data stores at a high level of detail.

Four Different Types of DFDS

Current Logical
- Physical aspects of system are removed as much as possible
- Current system is reduced to data and processes that transform them
New Logical
- Includes additional functions
- Obsolete functions are removed
- Inefficient data flows are reorganized
New Physical
- Represents the physical implementation of the new system
Current Physical
- Process label includes an identification of the technology (people or systems) used to process the data
- Data flows and data stores are labeled with the actual name of the physical media on which data flow or in which data are stored

Here are some of a Data Flow Diagram of the Pre-enrolment system:

a. CONTEXT DIAGRAM