Module 6 — Sequence Diagrams

Theory 20 minutes + Workshop 60 minutes

Duration: 80 minutes. Artefact produced: interaction sequence diagram.

What you will learn

Show runtime flow

Describe how actors, systems, services, and events interact over time.

Expose handoffs

Identify where responsibility, latency, failure, or control changes between parties.

Clarify integration

Make API calls, events, requests, and responses visible enough for delivery.

Support operations

Use the flow to discuss monitoring, recovery, support, and exception handling.

Sequence diagrams explain behaviour

A component diagram shows structure. A sequence diagram shows behaviour. It explains what happens, in what order, between which participants, and where important handoffs occur. It is valuable when a decision depends on integration flow, error handling, ownership, performance, or operational support.

Model a critical interaction

Model the sequence for a user accessing a clinical application through cloud identity, integration services, application services, data services, logging, and monitoring.

Workshop task

Create a sequence diagram for one critical business transaction and label the main failure points.

Assessment prompt

Explain how the sequence diagram changes the architecture conversation compared with a static component view.

What to submit

Sequence diagram; participant list; failure points; monitoring and support notes.

Next module

Module 7 — Activity and Class Diagrams.