Extend websocket scope to event publication

This change extends the "websocket" scope to ApplicationContext events
published from StompSubProtocolHandler. This however will only work
with ApplicationEventMulticaster that multicasts events in the same
thread.

Issue: SPR-12172

spring-websocket/src/main/java/org/springframework/web/socket/messaging/StompSubProtocolHandler.java

@@ -228,24 +228,26 @@ public class StompSubProtocolHandler implements SubProtocolHandler, ApplicationE
 				headerAccessor.setUser(session.getPrincipal());
 				headerAccessor.setImmutable();
 
-				if (this.eventPublisher != null) {
-					if (StompCommand.CONNECT.equals(headerAccessor.getCommand())) {
-						this.stats.incrementConnectCount();
-						publishEvent(new SessionConnectEvent(this, message));
-					}
-					else if (StompCommand.DISCONNECT.equals(headerAccessor.getCommand())) {
-						this.stats.incrementDisconnectCount();
-					}
-					else if (StompCommand.SUBSCRIBE.equals(headerAccessor.getCommand())) {
-						publishEvent(new SessionSubscribeEvent(this, message));
-					}
-					else if (StompCommand.UNSUBSCRIBE.equals(headerAccessor.getCommand())) {
-						publishEvent(new SessionUnsubscribeEvent(this, message));
-					}
+				if (StompCommand.CONNECT.equals(headerAccessor.getCommand())) {
+					this.stats.incrementConnectCount();
+				}
+				else if (StompCommand.DISCONNECT.equals(headerAccessor.getCommand())) {
+					this.stats.incrementDisconnectCount();
 				}
 
 				try {
 					SimpAttributesContextHolder.setAttributesFromMessage(message);
+					if (this.eventPublisher != null) {
+						if (StompCommand.CONNECT.equals(headerAccessor.getCommand())) {
+							publishEvent(new SessionConnectEvent(this, message));
+						}
+						else if (StompCommand.SUBSCRIBE.equals(headerAccessor.getCommand())) {
+							publishEvent(new SessionSubscribeEvent(this, message));
+						}
+						else if (StompCommand.UNSUBSCRIBE.equals(headerAccessor.getCommand())) {
+							publishEvent(new SessionUnsubscribeEvent(this, message));
+						}
+					}
 					outputChannel.send(message);
 				}
 				finally {
@@ -309,7 +311,14 @@ public class StompSubProtocolHandler implements SubProtocolHandler, ApplicationE
 			this.stats.incrementConnectedCount();
 			stompAccessor = afterStompSessionConnected(message, stompAccessor, session);
 			if (this.eventPublisher != null && StompCommand.CONNECTED.equals(command)) {
-				publishEvent(new SessionConnectedEvent(this, (Message<byte[]>) message));
+				try {
+					SimpAttributes simpAttributes = new SimpAttributes(session.getId(), session.getAttributes());
+					SimpAttributesContextHolder.setAttributes(simpAttributes);
+					publishEvent(new SessionConnectedEvent(this, (Message<byte[]>) message));
+				}
+				finally {
+					SimpAttributesContextHolder.resetAttributes();
+				}
 			}
 		}
 		try {
@@ -448,12 +457,12 @@ public class StompSubProtocolHandler implements SubProtocolHandler, ApplicationE
 			this.userSessionRegistry.unregisterSessionId(userName, session.getId());
 		}
 		Message<byte[]> message = createDisconnectMessage(session);
-		if (this.eventPublisher != null) {
-			publishEvent(new SessionDisconnectEvent(this, message, session.getId(), closeStatus));
-		}
 		SimpAttributes simpAttributes = SimpAttributes.fromMessage(message);
 		try {
 			SimpAttributesContextHolder.setAttributes(simpAttributes);
+			if (this.eventPublisher != null) {
+				publishEvent(new SessionDisconnectEvent(this, message, session.getId(), closeStatus));
+			}
 			outputChannel.send(message);
 		}
 		finally {