Building data flow diagram hierarchies in draw.io

draw.io: Your go-to tool for building data flow diagrams

With a wide range of features, including a number of data flow diagram templates, the option to generate diagrams using AI with our Smart Template feature, and a bespoke Data Flow Diagram shape library, draw.io is your go-to tool for building data flow diagrams (DFDs).

In this blogpost, we’ll be looking at two ways you can build your data flow diagrams containing different hierarchical levels, using:

1. Multipage diagrams, and,
2. Layers.

What do levels represent in data flow diagrams?

• Level 0 (aka “context diagram”): This is the most basic and highest-level DFD, presenting the entire system as a single process. It’s designed to be easily understood by anyone, regardless of their technical background.

• Level 1: This level breaks down the single process from the Level 0 DFD into its main subprocesses, offering greater insight into the system’s data flow and functionality.

• Level 2: Offering even more detail, Level 2 expands on the subprocesses from Level 1, showing their interactions with each other, as well as with data flows and data stores. This provides a detailed overview of the system’s internal operations.

• Level 3: While uncommon due to the aim of DFDs being to provide clarity and accessibility, a Level 3 DFD can be used for extremely complex systems. It maps out every aspect of a data process or system, providing the greatest level of detail.

How to build data flow diagrams

1. Multipage diagrams

How it works for DFDs: Create a separate page for each DFD level (e.g., Page 1 for Level 0, Page 2 for Level 1, Page 3 for Level 2, etc.). You can then link elements on a higher-level page (like a process bubble in Level 1) to the corresponding, more detailed diagram on a lower-level page.

The shape 1.5 contains a link to Level 2, where this process is broken down into more detail

Pros:

• Clear separation: Each level has its own dedicated canvas, which can make it easier to manage complex diagrams and prevent visual clutter.
• Easy navigation: Linking between pages provides a natural way to “drill down” into details, simulating the hierarchical nature of DFDs.
• Real-time collaboration in Confluence Cloud: Different team members can work on different DFD levels (pages) simultaneously within the same file.
• Presentation: When presenting the diagram in the Confluence page view mode, you can easily switch between pages to show different levels of detail.

Navigate between different pages of your multipage diagram in Confluence page view mode

2. Layers

How it works for DFDs: Build your DFD on a single page of your diagram, but place different levels of detail on separate layers. For example, the Level 0 diagram could be on a “Level 0” layer, and when you want to show Level 1, you make the “Level 1” layer visible (and hide Level 0, if necessary).

Use Layers to show and hide levels of diagram detail

Pros:

• Everything in one place: Your DFD levels exist on a single diagram page. You can toggle layers on and off to quickly show or hide details within the same diagram view.
• Contextual awareness: You can keep the higher-level elements visible (e.g. using a locked layer to avoid editing the wrong layer) while working on lower-level details.
• Presentation: When presenting the diagram in the Confluence page view mode, you can easily show or hide different layers to show different DFD levels.

Navigate between different layers of your DFD diagram in Confluence page view mode

Multipage diagram vs. layers: Which should you choose?

To sum up:

• Multipage diagrams offer a cleaner, more organized structure for truly distinct levels (Level 0, Level 1, Level 2). The ability to link between them effectively provides the “drill-down” functionality that’s key to hierarchical DFDs. This is ideal for large, complex systems where a single canvas with many layers would become unmanageable.

• Layers are excellent for showing variations or progressive detail within a single level, or for overlaying annotations, additional information, or different perspectives on the same base diagram. For example, you might use layers to show data flows in different scenarios (e.g., “Normal Flow” layer, “Error Handling Flow” layer) on a single Level 1 diagram.

For building hierarchical DFDs, a combination of both multipage diagrams and layers can be powerful, and deciding between one or the other will depend on your individual use case and personal preference.

While both functionalities offer various advantages, multipage diagrams, especially when combined with strategic linking between shapes across different pages, offer a powerful approach to represent distinct DFD levels. This approach offers the best of both worlds: clear separation and navigation between major DFD levels, while still allowing for detailed views or variations using layers if needed on individual pages.

Keep your data flowing