Context diagrams show the interactions between a system and other actors (external factors) with which the system is designed to interface. System context diagrams can be helpful in understanding the context which the system will be part of. They are used early in a project to get agreement on the scope and can be included in a requirements document. A context diagram shows the entire system as a single process.
Steps:
- Label the system/process in the centre – name of system/process usually contains a verb
- Identify entities that interact directly with the system/process – entities are usually a noun
- Group like entities
- Identify major flows of data between the entity and system/process
Notation:
- Systems/Processes are shown as squares with rounded corners
- External entities are shown as squares
- Data stores are shown as elongated, flat rectangles
- Data flows are shown as arrows
Example context diagram:
