Purpose: The purpose of the Data Flow Diagram is to document a system’s or part of a system’s data flows; the data input the system (or a process within the system) consumes and the data output the system produces.
Core concerns: The Data Flow Diagram enables you to model Processes, Data Stores, External Entities, Control Processes and Control Stores. These elements can then be connected by either Data Flows or Control Flows.
Graphical representation of the elements:
The Data Flow Diagram can show different levels of processes within a system that exchange data, and illustrate how those exchanges occur. As such, the model can document a system’s functional hierarchies.
Below, you can see an example of a Data Flow Diagram showing the Data Flows between several Data Stores, Processes and External Entities in a Bookshop:
The next example shows the Data Flow between process, Data Stores and External Entities for a Highway Repair Service:
The final example shows the Data Flows between Processes, Datastores and External Entities in an Outlook Mailbox:
Relation to other templates: The Processes in the Data Flow Diagram can be decomposed into more detailed Data Flow Diagrams to comprise the total functional model. The top level of a Data Flow Diagram is sometimes called a Context Diagram. However, in QLM we use the Data Flow Diagram template for the higher levels as well as the more detailed ones.
The Data Flow Diagram can be a decomposition of an Information System. It can offer a more detailed view of Data Flows than, for example, the Application Architecture Diagram.
An Information System could likewise be decomposed into a Business Process Diagram which offers a complimentary view less concerned with Data Stores and Data Flow, and more concerned with Activity Flow.
Properties and metadata: The Data Flow Diagram template can for example retain the following information:
- A description of the diagram
- Link to the owner of the diagram
- Link to the one responsible for diagram
- Audits (auto generated information regarding its current state and access rights)
- Associated documents, diagrams and other objects
- Inherent Risk detailing risk considerations
- Governance information detailing information about the published diagram and who has been involved in the approval of the diagram
The above picture shows the properties dialogue window for the Data Flow Diagram template, where you can view and edit the diagram’s properties in QualiWare Lifecycle Manager.