PublishSubscribeArchitekturen

Publish-subscribe (pub/sub) is a messaging pattern in which publishers emit messages to a topic or channel without knowledge of which subscribers will receive them. Subscribers express interest in specific topics and receive messages via a broker or a distributed event bus. This decouples producers from consumers in time, space, and synchronization.

In a typical pub/sub system, producers publish messages to named topics. Subscribers register their interest in topics, and a broker routes messages to all subscribers subscribed to those topics. Some systems support wildcard topics and content-based routing. Brokers may persist messages, enabling durable delivery, and may provide at-least-once delivery guarantees.

Pub/sub systems vary in architecture. Some are broker-based, with a central server that fan-outs messages (examples include MQTT, AMQP-based services, and many cloud offerings). Others are brokerless, relying on a distributed network of nodes. Streaming platforms like Apache Kafka treat topics as logs and deliver messages to consumers in the order they were written; cloud services like Google Pub/Sub provide managed pub/sub capabilities.

Common use cases include real-time notifications, event-driven architectures, telemetry and IoT data collection, and scalable broadcast of updates. Advantages include loose coupling, scalability, and resilience; challenges include ordering guarantees, delivery semantics, duplicate handling, and operational complexity in configuring topics and retention.