Sending notifications from your Spring Boot application to an external application can be achieved in various ways, depending on your specific requirements and the capabilities of the external application. Here are a few options: HTTP Webhooks: If the external application provides an HTTP endpoint (webhook) to receive notifications, you can send HTTP POST requests from your Spring Boot application to that endpoint whenever you want to send a notification. This is a simple and widely used method for integrating with external systems. Message Queues: Use a message queue system like Apache Kafka, RabbitMQ, or Apache ActiveMQ to send messages to the external application. Your Spring Boot application can produce messages to a topic/queue, and the external application can consume messages from that topic/queue. This approach decouples the sender and receiver, ensuring reliable delivery and scalability. RESTful API Calls: If the external application exposes RESTful APIs for receiving not...