Publisher Subscriber Pattern

• One way messaging pattern that involves multiple subscribers who can listen to messages
• Messages are generated by a publisher and can be categorized by topic
• Subscribers can recieve messages as per topic subscriptions
• Similar in concept to the observer pattern
• A message broker facilitates transport of messages between the publisher and the subscribers
• Brokers such as RabbitMQ and ActiveMQ Apollo are popular in the enterprise world
• Useful when working with Microservices and serverless architectures
• Message deliverability may post issues if the broker goes down, misconfigured or crashes