Integration
Patterns

The API Gateway pattern places a single entry point in front of a collection of backend services. The gateway handles cross-cutting concerns — authentication, rate limiting, request routing, protocol translation, and response aggregation — so that individual services do not need to implement them independently. Clients interact with one stable address; the internal service topology can change without affecting clients.

The Outbox pattern guarantees that a database update and the event publishing that must accompany it succeed together or fail together — without using a distributed transaction. The event is written to an outbox table in the same database transaction as the business data. A separate relay process reads the outbox and publishes events to the message broker. The database transaction is the source of truth.

The Saga pattern coordinates a distributed transaction across multiple services without using a two-phase commit. Each step in the saga performs a local transaction and publishes an event or message to trigger the next step. If any step fails, compensating transactions undo the preceding steps. The saga guarantees eventual consistency without distributed locking.