Event-driven architecture.

also: event-driven architectures · event driven architecture · EDA

Services emit events (OrderCreated) onto a bus and others react to them, instead of calling each other in a synchronous chain.

the two-minute refresher

Instead of Order → Inventory → Email → Analytics calls, the order service emits one event.
Loose coupling: services don't know about each other, and new consumers are easy to add.
One slow or failed consumer no longer breaks the request that produced the event.
Costs: eventual consistency, harder tracing, and you must handle duplicate and out-of-order events.

also: event-driven architectures · event driven architecture · EDA

Services emit events (OrderCreated) onto a bus and others react to them, instead of calling each other in a synchronous chain.

Instead of Order → Inventory → Email → Analytics calls, the order service emits one event.
Loose coupling: services don't know about each other, and new consumers are easy to add.
One slow or failed consumer no longer breaks the request that produced the event.
Costs: eventual consistency, harder tracing, and you must handle duplicate and out-of-order events.