Description: An ‘Application Event’ in the context of Spring Boot refers to a mechanism that allows communication between different components of an application through the publishing and listening of events. This design pattern is based on the principle of decoupling, where event emitters do not need to know about receivers, facilitating code extensibility and maintenance. In many programming frameworks, events are objects that encapsulate information about something that has occurred in the application and can be published using an application context. Components that are interested in these events can subscribe to them and react accordingly. This functionality is particularly useful in microservices-based architectures, where interaction between different services can be complex. Application events allow systems to respond to state changes, such as the creation of a new user or the updating of an order, in an asynchronous and efficient manner. Additionally, many frameworks provide a series of annotations and utilities that simplify the implementation of this pattern, such as `@EventListener` for listening to events and `ApplicationEventPublisher` for publishing them. In summary, application events in programming frameworks are a powerful tool for building reactive and scalable applications, promoting a clean and modular design.
