What type of exception would you use to handle a situation where it is impossible to establish a connection with a microservice in a booking system?

To handle situations where it is impossible to establish a connection with a microservice in the booking system, network-related exceptions are usually used. In Java, these can be:

• IOException or its subclasses, if standard input-output is used for network operations.
• Specialized exceptions, such as ConnectException, which indicates a failure to establish a connection.

If an HTTP client (e.g., HttpClient or RestTemplate) is used in the project, there may be specific exceptions, such as ResourceAccessException in Spring.

For more precise handling, you can create a custom exception, such as ServiceUnavailableException, which signals that the microservice is unavailable:

public class ServiceUnavailableException extends RuntimeException {
    public ServiceUnavailableException(String message) {
        super(message);
    }
}

Thus, when a connection cannot be established, this exception can be thrown and handled at the business logic level.