What are the architectural considerations for event-driven integration using SAP Event Mesh?

SAP Event Mesh provides publish-subscribe, asynchronous messaging between systems — a producer emits an event (like "sales order created") without knowing or caring which consumers exist, and any number of interested subscribers can react independently, decoupling producers and consumers from each other's availability and release schedules.

flowchart LR
    A[S/4HANA: SalesOrderCreated event] --> B[Event Mesh]
    B --> C[Extension 1: send notification]
    B --> D[Extension 2: update analytics]
    B --> E[Extension 3: trigger fulfillment]

Key architectural considerations include: designing event schemas that are stable and versioned (since multiple independent consumers depend on them), handling eventual consistency implications (a subscriber might process an event seconds or minutes after it occurred, not instantaneously), and ensuring idempotent event handling (a consumer should behave correctly even if it receives the same event more than once, which can happen in distributed messaging systems). This shifts integration thinking from "call and wait for a response" to "react to what happened," which requires genuinely different design patterns than synchronous API integration.