Existing approach — stateless web backend

external effects, saga state, and read-model duplication all live in application infrastructure

Existing approach — stateless web backend external effects, saga state, and read-model duplication all live in application infrastructure Web Client · Architecture component Web Client Load Balancer · Architecture component Load Balancer Order API · Architecture component Order API Idempotency · Store · Stateless Web Backend Idempotency Store Event Log · + Outbox · Stateless Web Backend Event Log + Outbox Order State · DB · Stateless Web Backend Order State DB Inventory · Service · Architecture component Inventory Service Saga · Orchestrator · Stateless Web Backend Saga Orchestrator Payment · PSP · Architecture component Payment PSP Scheduler · Stateless Web Backend Scheduler Read Model · Stateless Web Backend Read Model Accepted OrderId poll resume Stateless Web Backend

Stateless Web Backend responsibilities

  • • Saga Orchestrator decides the next step from the event log/outbox and writes back to the Order State DB, Event Log, and Read Model.
  • • The Scheduler resumes an interrupted saga (dashed = attached overhead, not core business flow).
  • • The client polls CommerceApi for status; CommerceApi also reads the Read Model directly.