What is the difference in using a Shared EventBus versus a Local queue in event-driven architecture and which one should be chosen?

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A shared EventBus and a local queue are two different implementations of event-driven architecture.

A shared EventBus enables communication between different components in a system through events. It is a centralized messaging system that acts as a mediator between the different components, enabling them to communicate with each other in a loosely coupled way. The EventBus receives events from the publisher (producer) and forwards them to the subscriber (consumer) components that have registered to receive those events. This enables different components to communicate with each other without being aware of each other's existence, making it easier to manage and scale the system.

On the other hand, a local queue is a messaging system that is specific to a single component. It enables asynchronous communication between different parts of the same system without having to go through a centralized EventBus. In this case, the publisher puts messages into the queue and the consumer retrieves them when they are ready.

Both options have their benefits and drawbacks, and the choice between the two depends on the specific use case. A shared EventBus is ideal for large and complex systems with multiple components that need to communicate with each other. It enables independent development and testing of the components, and it is easier to troubleshoot errors. However, it can become a bottleneck if the number of events generated is too high.

On the other hand, a local queue is a good option for systems with fewer components that need to communicate asynchronously. It has lower latency and is more efficient, but it can become difficult to manage as the number of components and messages increases.