dfd

Introduction to Data Flow Diagrams (DFDs)

  • DFDs provide a visual representation of information flow through a system or process.

  • They help organizations understand, perfect, and implement new processes or systems.

  • Ranges from simple overviews to complex displays, aiding in identifying potential problems and improving efficiency.

Types of Data Flow Diagrams

1. Logical Diagrams

  • Show theoretical information flow in a system.

  • Illustrate data origins, transformations, and destinations.

2. Physical Diagrams

  • Represent practical elements affecting information flow (software, hardware, employees).

  • Can be used in conjunction with logical diagrams for a detailed understanding.

Benefits of Data Flow Diagrams

1. Accessibility

  • Easier for stakeholders to comprehend complex concepts compared to text.

  • Visual presentations enhance information retention.

2. Clarity

  • Clarifies necessary systems and processes for teams.

  • Helps align team understanding and improves tracking of business operations.

3. Productivity

  • Reduces errors through enhanced understanding of systems.

  • Insights from DFDs aid in streamlining operations, improving team productivity.

Data Flow Diagram Symbols

  • DFDs use standardized symbols (rectangles, circles, arrows) to represent:

    • External Entity: Outside systems that send/receive data; usually found at the edges of the diagram.

    • Process: Manipulates data, producing outputs from incoming data.

    • Data Store: Holds data for later use, like files waiting to be processed.

    • Data Flow: Represents the path data takes within the system, depicted with arrows.

  • Common notation methods: Yourdon & De Marco, Gene & Sarson, SSADM, and Unified.

Levels of Data Flow Diagrams

Level 0: Context Diagram

  • Provides a high-level overview of system processes and data sources.

  • Simple and straightforward, easily understood by anyone.

Level 1: Process Decomposition

  • More details than Level 0, breaks down system's processes into subprocesses.

Level 2: Deeper Dives

  • Further breakdown of Level 1 processes into granular subprocesses.

Level 3: Increasing Complexity

  • Uncommon due to the level of detail required, which may hinder understanding.

Examples of Data Flow Diagrams

  1. Level 0 DFD:

    • Showcases a securities trading platform, detailing data flow between customer service, brokers, and the platform.

  2. Level 1 DFD:

    • Specific illustration yet to be provided.

  3. Level 2 DFD:

    • Decomposes the "Place Order" process, including steps for both customers and brokers, showing interaction with third-party stock exchange.