Provide @WebSocketScope annotation and public SCOPE_WEBSOCKET constant

Closes gh-35235

Author: jhoeller

framework-docs/modules/ROOT/pages/web/websocket/stomp/scope.adoc

@@ -1,8 +1,8 @@
 [[websocket-stomp-websocket-scope]]
 = WebSocket Scope
 
-Each WebSocket session has a map of attributes. The map is attached as a header to
-inbound client messages and may be accessed from a controller method, as the following example shows:
+Each WebSocket session has a map of attributes. The map is attached as a header to inbound
+client messages and may be accessed from a controller method, as the following example shows:
 
 [source,java,indent=0,subs="verbatim,quotes"]
 ----
@@ -20,13 +20,13 @@ public class MyController {
 You can declare a Spring-managed bean in the `websocket` scope.
 You can inject WebSocket-scoped beans into controllers and any channel interceptors
 registered on the `clientInboundChannel`. Those are typically singletons and live
-longer than any individual WebSocket session. Therefore, you need to use a
-scope proxy mode for WebSocket-scoped beans, as the following example shows:
+longer than any individual WebSocket session. Therefore, you need to use
+WebSocket-scoped beans in proxy mode, conveniently defined with `@WebSocketScope`:
 
 [source,java,indent=0,subs="verbatim,quotes"]
 ----
 	@Component
-	@Scope(scopeName = "websocket", proxyMode = ScopedProxyMode.TARGET_CLASS)
+	@WebSocketScope
 	public class MyBean {
 
 		@PostConstruct

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/WebSocketMessageBrokerConfigurationSupport.java

@@ -54,10 +54,18 @@
  * @author Rossen Stoyanchev
  * @author Artem Bilan
  * @author Sebastien Deleuze
+ * @author Juergen Hoeller
  * @since 4.0
  */
 public abstract class WebSocketMessageBrokerConfigurationSupport extends AbstractMessageBrokerConfiguration {
 
+	/**
+	 * Scope identifier for WebSocket scope: "websocket".
+	 * @since 7.0
+	 */
+	public static final String SCOPE_WEBSOCKET = "websocket";
+
+
 	private @Nullable WebSocketTransportRegistration transportRegistration;
 
 
@@ -137,7 +145,7 @@ protected void configureWebSocketTransport(WebSocketTransportRegistration regist
 	@Bean
 	public static CustomScopeConfigurer webSocketScopeConfigurer() {
 		CustomScopeConfigurer configurer = new CustomScopeConfigurer();
-		configurer.addScope("websocket", new SimpSessionScope());
+		configurer.addScope(SCOPE_WEBSOCKET, new SimpSessionScope());
 		return configurer;
 	}
 

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/WebSocketScope.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2002-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.socket.config.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Scope;
+import org.springframework.context.annotation.ScopedProxyMode;
+import org.springframework.core.annotation.AliasFor;
+
+/**
+ * {@code @WebSocketScope} is a specialization of {@link Scope @Scope} for a
+ * component whose lifecycle is bound to the current WebSocket lifecycle.
+ *
+ * <p>Specifically, {@code @WebSocketScope} is a <em>composed annotation</em> that
+ * acts as a shortcut for {@code @Scope("websocket")} with the default
+ * {@link #proxyMode} set to {@link ScopedProxyMode#TARGET_CLASS TARGET_CLASS}.
+ *
+ * <p>{@code @WebSocketScope} may be used as a meta-annotation to create custom
+ * composed annotations.
+ *
+ * @author Juergen Hoeller
+ * @since 7.0
+ * @see org.springframework.context.annotation.Scope
+ * @see WebSocketMessageBrokerConfigurationSupport#SCOPE_WEBSOCKET
+ * @see org.springframework.stereotype.Component
+ * @see org.springframework.context.annotation.Bean
+ */
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Scope(WebSocketMessageBrokerConfigurationSupport.SCOPE_WEBSOCKET)
+public @interface WebSocketScope {
+
+	/**
+	 * Alias for {@link Scope#proxyMode}.
+	 * <p>Defaults to {@link ScopedProxyMode#TARGET_CLASS}.
+	 */
+	@AliasFor(annotation = Scope.class)
+	ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;
+
+}