Phase C, Information Systems ArchitectureDerived from C4 Model

C4 System Context Diagram

Show one software system, the people who use it and the systems it depends on, so the scope boundary is agreed before any deeper design.

All tools

C4 system context: who uses a system and what it depends on

A C4 context diagram puts one software system in the centre, shows the people who use it and the systems it relies on, and labels every relationship between them.

C4 system context: who uses a system and what it depends on A C4 model system context diagram for a distribution network operator. In the centre is the LTDS publication system. Across the top, two people use it: a connections customer who reads capacity data, and an Ofgem analyst who reviews it. Across the bottom, two external systems it depends on: a GIS for network geography, and an asset register for ratings. Labelled arrows show each relationship, such as reads data from and reviews. PERSON Connections customer Checks where capacity exists PERSON Ofgem analyst Reviews compliance and data SOFTWARE SYSTEM LTDS publication system Publishes network capacity data EXTERNAL SYSTEM GIS Network geography and routes EXTERNAL SYSTEM Asset register Ratings and asset records Reads data from Reviews Reads geography from Reads ratings from Inside Source: Simon Brown, c4model.com

Start here before any deeper diagram. It fixes the system boundary and names the people and neighbouring systems, so everyone agrees what is inside the scope and what is outside it.

At the start of solution or technology design, to fix what sits inside the system and what sits outside it.

What you need and what you get

You'll need

  • The software system in scope
  • Its users and the neighbouring systems it touches

You'll get

  • A bounded context diagram
  • Named relationships across the system boundary

Taught in

No course modules linked yet.

Derived from

  • Simon BrownSimon Brown, C4 model, level 1 System ContextSource