Coordination & Transactions

Why coordination

Distributed systems need coordination for correctness: locks, leases, consensus, and transactions for multi-step workflows.

2PC vs Saga

• Two-Phase Commit (2PC): atomic but can block
• Saga: break a transaction into steps with compensations

What you will build

• Determine saga compensations after a failure
• Decide 2PC outcome from participant votes
• Enforce fencing tokens for stale leaders