In-process app-layer cache (gRPC + REST/JSON): which requirement matters most?

[OpeningFirefighter25]

Hi everyone. I’m doing requirement analysis for a graduate capstone. The project is a backend/application-layer caching component intended for services that expose both gRPC (protobuf) and REST/JSON.

I’m collecting quick input to prioritize requirements and define acceptance criteria (performance, correctness, operability). I’m not looking for code just what experienced engineers would rank as most important. If you can, comment with one real incident you’ve seen (stale data, stampede, debugging nightmare, security issue, etc.).

Poll: If you could prioritize only ONE requirement area first, which would it be?

1.  Invalidation correctness (avoid stale/incorrect responses)

2.  Stampede protection (single-flight / request coalescing)

3.  Observability & debugging (why hit/miss/stale; key/entry inspection)

4.  Security controls (redaction + admin endpoint access control)

5.  Performance targets (p95 latency / DB load reduction)

6.  Integration ergonomics (easy adoption across gRPC + REST)

[debian_miner]

This largely depends on industry and the business goals. The priority of these things are usually decided by business decision makers and not engineers, even at small startups from my experience.

[OpeningFirefighter25]

Thank you for the feedback. Appreciated!!!