[PT선생님][36]com.sun.nio.sctp.AbstractNotificationHandler 알아보기

com.sun.nio.sctp.AbstractNotificationHandler는 Java 7에서 도입된 클래스로, SCTP (Stream Control Transmission Protocol) 프로토콜을 사용하는 네트워크 응용 프로그램에서 사용할 수 있습니다.

SCTP는 TCP와 UDP와 같은 전송 계층 프로토콜입니다. SCTP는 멀티홈, 다중 스트림, 데이터 청크, 높은 신뢰성 및 서비스 품질(QoS) 제어 등의 기능을 제공합니다. 이러한 기능은 일부 응용 프로그램에서 매우 중요하며, SCTP는 이러한 응용 프로그램에서 TCP 또는 UDP 대신 사용될 수 있습니다.

AbstractNotificationHandler 클래스는 com.sun.nio.sctp 패키지의 하위 클래스로, SCTP Notification API를 구현합니다. 이 API는 SCTP 스트림에서 발생하는 이벤트를 처리하고 처리기를 등록하는 방법을 제공합니다. SCTP에서는 이벤트가 발생하면 Notification 메시지를 보내고, Notification 메시지를 받은 응용 프로그램은 등록된 NotificationHandler 객체의 적절한 메서드를 호출하여 이벤트를 처리합니다.

AbstractNotificationHandler 클래스는 Notification 메시지를 처리하기 위한 기본 클래스입니다. 이 클래스를 상속하여 사용자 지정 NotificationHandler를 작성할 수 있습니다. 이 클래스는 NotificationHandler 인터페이스를 구현하여 SCTP 스트림에서 발생하는 이벤트를 처리할 수 있도록 합니다.

AbstractNotificationHandler 클래스의 주요 메서드는 handleNotification()입니다. 이 메서드는 Notification 메시지를 처리하기 위해 호출됩니다. 사용자 지정 NotificationHandler에서는 이 메서드를 오버라이드하여 Notification 메시지를 처리하는 코드를 작성할 수 있습니다.

이 클래스는 com.sun.nio.sctp 패키지의 일부이므로, 이 패키지를 사용하려면 Java의 보안 모델과 관련된 몇 가지 문제를 고려해야 합니다. 따라서, 이 패키지를 사용하는 경우에는 주의해야 하며, 신중하게 검토해야 합니다.AbstractNotificationHandler 클래스는 추상 클래스이므로 직접 인스턴스화할 수 없습니다. 대신 이 클래스를 상속하여 사용자 지정 NotificationHandler 클래스를 작성해야 합니다.

사용자 지정 NotificationHandler 클래스를 작성하려면 AbstractNotificationHandler 클래스의 하위 클래스를 만들고, 이 클래스에서 handleNotification() 메서드를 오버라이드하여 Notification 메시지를 처리하는 코드를 작성해야 합니다. 이 때, handleNotification() 메서드의 매개변수로는 Notification 객체가 전달됩니다. 이 객체는 Notification 메시지에 대한 정보를 포함합니다.

AbstractNotificationHandler 클래스에는 또한 exceptionOccurred() 메서드도 있습니다. 이 메서드는 SCTP 스트림에서 예외가 발생했을 때 호출됩니다. 이 메서드도 사용자 지정 NotificationHandler에서 오버라이드할 수 있습니다.

AbstractNotificationHandler 클래스는 Java 7에서 도입된 SCTP API의 일부입니다. SCTP는 일부 응용 프로그램에서 매우 중요한 기능을 제공하므로, 이 API는 이러한 응용 프로그램을 구현하는 데 매우 유용합니다. 그러나 이 클래스와 SCTP API는 Java의 보안 모델과 관련된 몇 가지 문제가 있으므로, 사용할 때는 주의해야 합니다.다음은 AbstractNotificationHandler를 상속하는 사용자 정의 NotificationHandler 클래스의 예제 코드입니다. 이 코드는 SCTP 스트림에서 이벤트를 처리하는 방법을 보여줍니다.

 

import java.net.*;
import java.nio.*;
import java.util.*;

import com.sun.nio.sctp.*;

public class MyNotificationHandler extends AbstractNotificationHandler {

    @Override
    public HandlerResult handleNotification(Notification notification, Object attachment) {
        if (notification instanceof AssociationChangeNotification) {
            AssociationChangeNotification associationChangeNotification = (AssociationChangeNotification) notification;
            Association association = associationChangeNotification.association();
            if (associationChangeNotification.event().equals(SctpNotification.AssocChangeEvent.COMM_UP)) {
                // Handle association established event
                System.out.println("Association established with " + association.getRemoteAddresses());
            } else if (associationChangeNotification.event().equals(SctpNotification.AssocChangeEvent.SHUTDOWN)) {
                // Handle association shutdown event
                System.out.println("Association with " + association.getRemoteAddresses() + " has been shutdown");
            }
        } else if (notification instanceof PeerAddressChangeNotification) {
            PeerAddressChangeNotification peerAddressChangeNotification = (PeerAddressChangeNotification) notification;
            InetAddress address = peerAddressChangeNotification.address();
            if (peerAddressChangeNotification.event().equals(SctpNotification.AddressChangeEvent.ADDR_AVAILABLE)) {
                // Handle new address available event
                System.out.println("New address " + address + " is available");
            } else if (peerAddressChangeNotification.event().equals(SctpNotification.AddressChangeEvent.ADDR_REMOVED)) {
                // Handle address removed event
                System.out.println("Address " + address + " has been removed");
            }
        } else if (notification instanceof SendFailedNotification) {
            SendFailedNotification sendFailedNotification = (SendFailedNotification) notification;
            List<Integer> transmitFailures = sendFailedNotification.transmitFailed();
            for (int transmitFailure : transmitFailures) {
                // Handle send failure event
                System.out.println("Failed to send message to stream " + transmitFailure);
            }
        } else if (notification instanceof ShutdownNotification) {
            // Handle shutdown event
            System.out.println("Shutdown event received");
        }
        return HandlerResult.CONTINUE;
    }
}

이 코드는 handleNotification() 메서드를 오버라이드하여 SCTP 스트림에서 발생하는 다양한 이벤트를 처리합니다. 이 예제 코드는 SCTP 연결 이벤트, 피어 주소 변경 이벤트, 전송 실패 이벤트 및 종료 이벤트를 처리합니다.

MyNotificationHandler 클래스는 AbstractNotificationHandler 클래스를 상속합니다. 이 클래스의 handleNotification() 메서드는 Notification 객체를 매개변수로 받아 이벤트를 처리합니다. 이 예제에서는 instanceof 연산자를 사용하여 Notification 객체의 유형을 확인하고, 이벤트에 따라 적절한 작업을 수행합니다.

SCTP 스트림에서 발생하는 이벤트는 SCTP Notification API를 통해 알림 메시지로 전달됩니다. 이 예제 코드에서는 MyNotificationHandler 클래스의 handleNotification() 메서드를 호출하여 이 알림 메시지를 처리합니다. 이를 통해 SCTP 스트림에서 발생하는 다양한 이벤트를 적절하게 처리할 수 있습니다.