Publish/subscribe mechanism used in Event-driven

microservices architecture.No point to point communication

Microservices don’t call each other, instead, they created

events and consume events from message broker systems

in an async way.

▪ AMQP (Advanced Message Queuing Protocol)

▪ Publish/Subscribe pattern with events

▪ Using AMQP protocols, the client sends the message with

using message broker systems like Kafka and RabbitMQ

queue.

▪ The producer service of the events doesn't know about its

consumer services. the consumers also don’t necessarily

know about the producer.

▪ Decouple services and build loosely coupled microservices.

▪ No clear central place or orchestrator, This increase

complexity of architecture.

Publish/subscribe mechanisms that has multiple receivers.

▪ Producer service publish a message and it consumes from

several microservices by subscribing message on the

message broker system.

▪ Publisher don't need to know any subscriber, no any

dependecy with communication parties.

▪ one-to-many (topic) implementation has Multiple receivers. Each

request can be processed by zero to multiple receivers.

▪ Publish/subscribe used in patterns Event-driven microservices

architecture.

▪ Message broker system is publishing events between multiple

microservices, subscribing these events in an async way.

▪ Messages are available to all subscribers and the topic can

have more than one subscriber.

▪ The message remains persistent in a topic until they are deleted.

▪ Kafka, RabbitMQ or Amazon SNS and EventBridge.

Fan-out is a messaging pattern; ‘fanned out’ to multiple

destination in parallel.

▪ Each of destinations can work and process this messages in

parallel.

▪ Publisher/subscriber model to define a topic which is

logical access point to enabling message communication with

asynchronously.

▪ Publisher sends the message to the topic, message is

immediately fanned out to all subscribers of this topic.

▪ Each service can operate and scale independently and

individually that completely decoupled and asnycronously.

▪ The publisher and the subscribers don’t need to know who is

publishing / consuming this message that is broadcasting.

▪ Deliver the same message to multiple receivers is to use the

Fanout Publish/Subscribe Messaging Pattern.

https://learn.microsoft.com/en-us/dotnet/architecture/microservices/architect-microservice-container-applications/asynchronous-message-based-communication