Event Bus overview

Publish-subscribe backbone that decouples event producers from consumers, enabling event-driven architectures across microservices. Producers publish events to named topics/channels; consumers subscribe and react asynchronously, providing temporal decoupling and fan-out. Apache Kafka is the dominant high-throughput option with strong ordering guarantees per partition and durable log retention. AWS EventBridge provides serverless routing with content-based filtering and schema registry. NATS offers extremely low-latency pub/sub for service meshes. Key concerns include at-least-once vs exactly-once delivery semantics, consumer group lag monitoring, topic partitioning, and schema evolution.