Publisher-Subscriber

is a design pattern that allows multiple components of a system to communicate asynchronously and decouple their dependencies.

• The publisher sends a message to a broker.
• One or more subscribers receive the messages from a broker.
• The broker can be a server or servers, with fault tolerance and load balancing.
• The broker uses queues or buffers to deliver the messages to the receivers.
• The queues or buffers are usually labeled as topics or channel names.
• The storage of the messages can be persistent or transient, depending on the requirements.
• Messages can use different formats: binary, JSON, XML, and text.
• Pros: Decoupling, scalability, and reliability.
• Popular systems: Kafka, AWS SNS, Azure Service Bus, RabbitMQ, and Redis.