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.