What changes after this module
Protect service-to-service communication with clearer trust assumptions, stronger contracts, and tighter validation at the boundary.
Outcome promise
- Explain why API contracts, authentication, and validation matter to service security.
- Spot one trust assumption in a service interaction that needs tightening.
Core model
Use the diagram and terms below as the minimum model you should be able to explain after this module. If you cannot explain the model in plain language, pause here before you move on.
Key terms
- API contract
- The agreed structure and behaviour for requests, responses, and errors between services.
- Boundary validation
- Checking identity, data, and policy at the service edge before trust extends inward.
Check yourself
Answer the prompt before you reveal the check. If you cannot answer it in your own words, revisit the model and the terms once more.
Quick check
Why does transport encryption not solve API misuse by itself?
Reveal the answer check
Because you still need to verify identity, authorisation, rate limits, data structure, and allowed behaviour at the service boundary.
Reflection and evidence
Keep the evidence small. One honest reflection and one small artefact is enough to show that the learning changed how you describe, check, or design something.
Reflection prompt
Choose one integration you know. What does the receiving service trust too easily today?
Artefact
A short service-boundary note with one contract check and one trust assumption to reduce.
Optional deeper practice
Use the workspace to inspect one service interaction and note where contract, identity, or validation controls belong.
Move through the course
Keep the flow predictable. Stay with the stage sequence unless you have a clear reason to jump around.