eventdriven

Eventdriven is a term used to describe computing approaches in which software reacts to events rather than following a fixed sequence of steps. It encompasses both event-driven programming within applications and event-driven architecture (EDA) across systems. In event-driven programming, components register handlers for events and an event loop or dispatcher calls these handlers when events occur, such as user actions, timers, or messages from other parts of the system. This model is common in graphical interfaces and asynchronous runtimes.

In event-driven architecture, producers publish events to a broker or bus, and consumers subscribe to event streams. Events can be persisted or streamed for durability and auditability. This decouples producers from consumers and enables scalable, asynchronous communication in distributed systems. Architectures often include patterns such as event sourcing, where state changes are captured as a sequence of events, and CQRS, separating command handling from query processing.

Tools and implementations include event loops and callback-based runtimes (for example, Node.js), and distributed streaming systems and message brokers (such as Apache Kafka, RabbitMQ, or AWS EventBridge). Design choices include delivery semantics (at-least-once, exactly-once), ordering guarantees, and how to handle backpressure and schema evolution.

Use cases include user interfaces, real-time analytics, IoT data processing, and microservices communication. Its advantages include improved responsiveness, scalability, and decoupled components; disadvantages include complexity in debugging, tracing, and ensuring consistent state across services.