Introduction

  • DFD is one of the most important system tools used for a system to develop it.

Definition

  • A data flow diagram (DFD) is a visual/graphical representation of how data flows within a system or process or organization. 

Characteristics

  • It is a visual tool that can help us to understand, analyze, and document the data requirements of a system.
  • It is a graphical technique used to depict and analyze the flow of data, information, and materials within a business process or system.
  • DFDs are commonly used in software engineering and business analysis to model business processes, data flows, and data stores.
  • DFDs can be used to analyze existing systems, identify areas for improvement, and design new systems.
  • DFD can also be used to communicate system requirements and design to stakeholders and project team members.

DFD Notations

  • In a DFD, the system or process is represented as a set of interconnected components, such as data stores, inputs, outputs, and processes. Arrows or lines represent the flow of data between these components, and each component is labeled to indicate what it represents.
  • It uses symbols to depict the entities, processes, and data stores involved in the system, as well as the data flows between them.
  • A DFD consists of a set of interconnected symbols and arrows that represent the flow of data between various components of a system. The symbols used in a DFD include processes, data stores, data flows, and external entities. Processes represent activities that transform data, data stores represent where data is stored, data flows represent the movement of data between processes and data stores, and external entities represent sources or destinations of data outside the system being modeled.
  • The symbols used in a DFD typically include circles or bubbles to represent processes, rectangles to represent data stores, arrows to represent data flows, and open-ended rectangles to represent external entities or sources of data. The level of detail and complexity of a DFD can vary, depending on the scope of the system being represented and the level of abstraction desired.

Levels of DFD

  • The number of levels of DFDs used for a particular system depends on the complexity of the system being modeled and the level of detail required to fully understand the system.
  • Data flow diagrams (DFDs) can be divided into several levels or layers, each with increasing levels of detail. The different levels of DFDs are:
    • Context Level DFD:
      • This is the highest level of DFD that shows the overall view of the system and its interactions with external entities.
      • It represents the system as a single process and its relationship with external entities such as customers, suppliers, and other systems.
    • Level 0 DFD:
      • This level represents the main processes of the system and the data flows between them. It is a more detailed view of the system than the context-level DFD.
      • Level 0 DFD is also known as the fundamental system model.
    • Level 1 DFD:
      • This level breaks down the processes of the level 0 DFD into more detailed sub-processes. Each sub-process represents a more detailed description of the process and shows the data flow between the sub-processes.
      • It shows the functional decomposition of the system and the data flows between the sub-processes.
    • Level 2 DFD:
      • This level of DFD further decomposes the sub-processes of Level 1 DFD into their respective sub-sub-processes. This level of DFD provides a more detailed view of the system and shows how the data flows between the sub-processes.
      • It provides a more detailed view of the system processes and data flows.
    • Level 3 DFD:
      • This is practically the lowest level of DFD and provides the most detailed view of the system processes and data flows.
      • It shows the processes and data flows that make up the sub-processes of the level 2 DFD.

The different levels of DFDs allow for a progressive and detailed understanding of the system being modeled, from a high-level overview to a more granular view of the processes and data flows.

Use

  • Data flow diagrams are commonly used in software engineering and systems analysis to model business processes and information systems.
  • DFD is useful for identifying potential bottlenecks and inefficiencies in a system, as well as for documenting and communicating how a system works.
  • DFDs are useful for analyzing and designing systems, as they help to identify potential bottlenecks, redundancies, and other issues related to the flow of data.
  • DFD can also be used to communicate system requirements and specifications to stakeholders, such as developers, designers, and business analysts.

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Categories: Diagrams

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