Self-Contained Service

Design services to answer requests from local ownership data instead of chaining synchronous calls.

design

Detailed Description

A self-contained service avoids runtime dependency chains. It keeps enough local data to complete its responsibility.

The tradeoff is that data is copied through events or replication, so teams must accept and design for eventual consistency.

Visual Diagram

Anti-pattern (chatty):
  OrderSvc → UserSvc → InventorySvc
  all in one request = cascading failures

Self-Contained (correct):
  OrderSvc → handles locally
  syncs data async via events

Tradeoffs

Pros

Fast, resilient, avoids cascading failures

Cons

Data duplication and eventual consistency

Examples: Event-driven microservices with local projections