Staff+: Cross-org Migration

Interviewer

You need to migrate 5 microservices from REST to gRPC across 3 teams. No team reports to you. How do you make this happen?

Candidate

This is a classic staff-level influencing challenge. I can't mandate - I need to build alignment. First, I'd write a one-page RFC: Why gRPC? What's the problem with REST? (Performance, strong typing, streaming support). Include concrete data: current p99 latency, protobuf serialization benchmarks. Second, socialize the RFC individually with each team's tech lead. Get their concerns early. Maybe Team A just rewrote their API - they won't want to touch it for 6 months. That's fine, we can sequence. Third, find a pilot team. Work with them to migrate one service. Measure results. Use that data to convince the other teams. Fourth, create migration tooling: a code generator for protobuf <-> REST bridge, a migration checklist, a testing guide. Make it easy for teams to say yes. Fifth, set a timeline with milestones but no hard deadlines. Give teams autonomy to schedule within the quarter.

Interviewer

One team lead is resistant - they don't see the value and don't want to disrupt their roadmap.

Candidate

I'd dig into their specific concerns. Is it timing? Effort? Lack of conviction in gRPC? If it's timing: can we delay their migration to Q3 instead of Q2? If it's effort: can I assign an engineer from my team to help them? If it's conviction: I'd offer to do a lunch-and-learn with benchmarks, or have a team that already migrated share their experience. Ultimately, if the resistance is strong, I'd accept partial migration. Better to have 4 of 5 services migrated with a clean bridge pattern than force it and damage cross-team trust.