An event-driven architecture is a software design pattern in which microservices react to changes in state, called events. Events can either carry a state (such as the price of an item or a delivery address) or events can be identifiers (a notification that an order was received or shipped, for example).

Event-driven architecture (EDA) is a software design pattern that enables the construction of scalable and loosely coupled systems. Events representing occurrences or changes in the system drive the flow. They are generated by various sources, published to an event bus or message broker, and consumed by interested components asynchronously.

Event-driven architecture (EDA) is a design pattern where system components communicate by generating, detecting, and responding to events. Events represent significant occurrences, such as user actions or changes in the system state. In EDA, components are decoupled, allowing them to operate independently.

The event-driven architecture pattern consists of two main topologies, the mediator and the broker. The mediator topology is commonly used when you need to orchestrate multiple steps within an event through a central mediator, whereas the broker topology is used when you want to chain events together without the use of a central mediator.

Event-Driven Architecture Patterns An EDA pattern designates how event producers, routers, and consumers work together. There are two common patterns in EDA architecture: publisher/subscriber and event streaming. The following sections expand on both these designs.