A system diagram is a simple and very high level description of a system that exists or needs to be built. It is a simple diagram that can be drawn collaboratively in little time. It can help a team get a clear, complete, and common understanding of a system.
The components of a system diagram are:
The main enemy of system architects and software engineers is complexity. Complexity leads to a poor understanding of a system, which in turn can make the task of modifying or even using the system very challenging. The complexity of a system is reflected in its descriptions and documentation. The task of explaining a system to an audience of non technical people can be daunting. The System Diagram provides a simple method to solve this problem.
Identifying and describing all the components of a System Diagram should enable a team to get a good understanding of the system. If the diagram is too complex, perhaps it needs to be broken down into multiple integrated systems.
Gather the team around a blank whiteboard
Begin by drawing a large box in the middle of the canvas; this is your System Boundary
As a team, define the main Purpose of the system in one brief sentence and write it above the box
Define one or more Inputs that the system will receive from external actors
Define one or more Outputs that the system will provide to external actors
Define one or more Subsystems that are inside the Boundar; these typically process the inputs, but may perform other tasks as well
Define one or more Feedback loops that the system has in place to continously improve itself