Chapter 4 — RML-3 (History World): Irreversible History, Forward-Only Correction

The Worlds of Distributed Systems — Chapter 4 “Can you really make it as-if-it-never-happened by reverting the DB?” “...The outside world may already remember it.” In Chapter 2 we explored RML-1 (Closed World) : a room where failure is safe. In Chapter 3 we explored RML-2 (Dialog World) : recovery as conversation and reconciliation. Now we step into the third world: RML-3 — History World This is the world where you don’t “undo” events. You don’t erase the past. You layer corrections on top of what happened. 1) What is the History World? In one line: RML-3 is a world with shared history across multiple principals—and accountability for that history. 1.1 Typical RML-3 domains Finance bank transfers, card payments, securities trading Tax / accounting invoices, receipts, journal entries Healthcare / public infrastructure medical records, prescription history, critical public logs B2B / contracts purchase orders, fulfillment records, contractual obligations What these domains share: Records