Layer 3 · Go deeper · 8 min
Go deeper
Size it, build it, then make the calls an interviewer will push you on.
Back of the envelope
Size it up
Tap through each step of the arithmetic.
How much traffic does a valet key take off the app tier?
What does a sidecar in every pod cost in memory?
Build-up · 5 steps
Twelve patterns on one food app
Most patterns live at a predictable spot. Place each one where its problem lives on a food-delivery backend.
Step 1 of 5
One front door
The gateway routes by path and offloads TLS, token checks and limits. It accepts tokens from an identity provider, so apps don’t store passwords. That’s federated identity.
4 interview moments
You’re the candidate
The interviewer pushes on the hard parts. Pick an approach and see how it holds up.
Deep dive 1 of 4
Interviewer
“Users upload photos of up to 20 MB. How do the bytes reach storage?”
Your move. Pick an approach:
Deep dive 2 of 4
Interviewer
“A report export takes several minutes. The client calls POST /reports. What does the API return?”
Your move. Pick an approach:
Deep dive 3 of 4
Interviewer
“Admin screens are slow under read load. A teammate proposes CQRS across the whole system.”
Your move. Pick an approach:
Deep dive 4 of 4
Interviewer
“Your SaaS has large enterprise tenants, and some must keep their data in-country. How do you scale out?”
Your move. Pick an approach: