Data flow diagrams are effective tools for illustrating how information moves through a system. They provide varying degrees of granularity, each with a distinct function in system design and analysis. We'll go over all three DFD levels—Level 0, Level 1, and Level 2—as well as the crucial Context Diagram in this extensive guide.
In this article
Part 1: Overview of DFD Levels
Multiple levels are used in data flow diagrams to fully depict a system. Analysts and designers can concentrate on particular facets of the system because each level offers a unique viewpoint on the data flow within the system. The main DFD Levels are as follows:
Level 0: Context Diagram (Highest Level)
This is a system's most abstract viewpoint. It shows how the system communicates with outside entities and portrays the system as a single process.
Level 1: Top-Level Diagram
This level gives a high-level overview of the system's functionalities by breaking the system down into major processes and external entities.
Level 2: Subprocesses and Data Stores
Level 2 explores the procedures presented in Level 1 in greater detail. It provides a more in-depth view by dissecting these processes into smaller ones. Data stores are also introduced, indicating the location of data storage within the system.
Level 3: Fine-Grained Analysis
This level has the most details. To grasp the nuances of data flow within the system, Level 2 subprocesses are further dissected, and data stores are thoroughly described.
Context Diagram (Detailed)
This Context Diagram view is more in-depth and offers more information about how the system interacts with outside entities.
Part 2: Types of DFD
Logical Data Flow Diagram, or DFD:
A logical DFD is a high-level system representation that ignores the physical implementation and concentrates on the logical flow of data within the system.
- It offers an abstract perspective of the data flow within the system, highlighting the operations carried out on the data, the storage of data, and the interactions with external entities.
- "What" and "why" of a system's operations are the main concerns of logical DFDs, not "how."
- They are frequently employed in the early phases of system design and requirements analysis and help comprehend the fundamental operations and data flows of a system.
Physical Data Flow Diagram, or DFD:
The system is represented in more detail and with greater concreteness in a physical DFD, though. It focuses on the actual hardware—the locations, appliances, and physical parts of the system.
- Physical DFDs consider the specifics of implementation, including network connections, databases, hardware, and software.
- They focus on the "how" of a system's functioning, outlining the particular tools and technologies that are used for data processing and storage.
- Since accurate construction of physical DFDs necessitates a thorough understanding of the logical design, logical DFDs are typically created before physical DFDs.
In a nutshell, Physical DFDs offer a more in-depth, concrete view that takes into account the system's actual implementation, whereas logical DFDs offer a high-level, abstract view of a system's data flow and processes. Physical DFDs are used for detailed system design and implementation, while logical DFDs are utilized in the early planning stages of system analysis and design. Both forms of DFDs are useful tools in system analysis and design.
- Related reading: What Is Physical DFD and Logical DFD?
Part 3: How You Can Create Data Flow Diagram Levels with Wondershare Edrwamax
Step 1: Install and download EdrawMax
To begin, download and install EdrawMax on your desktop or laptop. This is an easy and powerful data flow diagram maker tool. It's available on the web and also as software.
Step 2: Launch EdrawMax
Open the EdrawMax application on your PC, and sign up or log in
Step 3: Go to “New”, to start a new project
Go to the "Flowchart" category.
Now choose the Data Flow Diagram Option appearing on the right side.
Step 4: Choose the template
Pick the template that most closely matches your requirements.
You can also make the whole data flow diagram by yourself
Step 5: Select the DFD level
Select the level at which the process and the physical or logical layers will be represented.
Step 6: Determine important entities and process
The main components of a data flow diagram are the important entities and the processes that link them.
As a result, you must determine the system's input and output sources as well as the processing methods for them.
Step 7: Insert Shapes
To add shapes to your canvas, drag and drop them from the library. Different components of your DFD diagrams are represented by these shapes.
Step 8: Join the Shapes
Connectors, such as lines and arrows, can be used to join the shapes in the sequence that they appear in your Data Flow diagrams.
Step 9: Label the Shapes by inputting the data
Double-click a shape to insert a description and give each step in your process a label. It makes the diagram easier for others to understand.
Step 10: Shape Customization
To alter a shape's size, color, or style, simply click on it and choose "Format."
Alternatively, you can also choose the background color, text font, etc., by going to the "design" menu and using these features to create your digital aesthetic.
Step 11: Export
When you're satisfied with your Data flow diagram, export it in a format of your choice and share it with the people who need it.
Conclusion
In system analysis and design, Data Flow Diagrams (DFDs) are essential for understanding and documenting information flow. An extensive understanding of the internal workings of the system can be obtained by analysts and designers through the use of various DFD levels, ranging from the high-level Context Diagram to the detailed Level 3.
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