Layer 2 - The subprocess layer
The subprocess layer of data-flow diagrams is the third layer. You should use it whenever you create systems that are highly sensitive. Data-flow diagrams at this layer contain separate data-flow diagrams detailing each system subpart.
Goal: Represent system subparts with enough context to help you understand how they work and interact with each other.
Similar to the process layer, data-flow diagrams in the system subprocess layer should fit in a single page and contain all processes for their respective system subparts.
Important
Check with your team to make sure this level of depth is required.
When to use the subprocess layer
Use the subprocess layer for systems the organization considers critical. A breach in a system subpart could put the entire system, customers, and organization at critical risk.
Examples include systems that:
- Are used in secured environments.
- Handle sensitive data.
- Have a high risk rating.
Deep diving into a system subpart
Any system subparts requiring deeper dives should follow the same rule from the process layer and have their own separate data-flow diagrams. The lower-level view allows users to "zoom-in" and "zoom-out" of the system with as much context and clarity as possible. Here's how:
| Step | Guidance |
|---|---|
| 1 | Create a process element with a clear description label, such as Input Parser Name. |
| 2 | Create a new file and name it exactly the same as the description label, with a tree-like structure, such as Web Service Name - Web Service Worker Name - Input Parser Name. |
| 3 | Focus the data-flow diagram only on the lower-level system subpart you're "zooming into." |
The result is a series of data-flow diagrams in the lower-level layer, known as layer 3.
Tip
The path-like file naming structure helps you differentiate between the different levels.