Selector header name is exposed for configuration

Issue: SPR-16732

spring-messaging/src/main/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistry.java

@@ -44,6 +44,7 @@ import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.PathMatcher;
+import org.springframework.util.StringUtils;
 
 /**
  * Implementation of {@link SubscriptionRegistry} that stores subscriptions
@@ -73,6 +74,7 @@ public class DefaultSubscriptionRegistry extends AbstractSubscriptionRegistry {
 
 	private volatile int cacheLimit = DEFAULT_CACHE_LIMIT;
 
+	@Nullable
 	private String selectorHeaderName = "selector";
 
 	private volatile boolean selectorHeaderInUse = false;
@@ -114,26 +116,28 @@ public class DefaultSubscriptionRegistry extends AbstractSubscriptionRegistry {
 	}
 
 	/**
-	 * Configure the name of a selector header that a subscription message can
-	 * have in order to filter messages based on their headers. The value of the
-	 * header can use Spring EL expressions against message headers.
-	 * <p>For example the following expression expects a header called "foo" to
-	 * have the value "bar":
+	 * Configure the name of a header that a subscription message can have for
+	 * the purpose of filtering messages matched to the subscription. The header
+	 * value is expected to be a Spring EL boolean expression to be applied to
+	 * the headers of messages matched to the subscription.
+	 * <p>For example:
 	 * <pre>
 	 * headers.foo == 'bar'
 	 * </pre>
-	 * <p>By default this is set to "selector".
+	 * <p>By default this is set to "selector". You can set it to a different
+	 * name, or to {@code null} to turn off support for a selector header.
+	 * @param selectorHeaderName the name to use for a selector header
 	 * @since 4.2
 	 */
-	public void setSelectorHeaderName(String selectorHeaderName) {
-		Assert.notNull(selectorHeaderName, "'selectorHeaderName' must not be null");
-		this.selectorHeaderName = selectorHeaderName;
+	public void setSelectorHeaderName(@Nullable String selectorHeaderName) {
+		this.selectorHeaderName = StringUtils.hasText(selectorHeaderName) ? selectorHeaderName : null;
 	}
 
 	/**
-	 * Return the name for the selector header.
+	 * Return the name for the selector header name.
 	 * @since 4.2
 	 */
+	@Nullable
 	public String getSelectorHeaderName() {
 		return this.selectorHeaderName;
 	}
@@ -143,25 +147,32 @@ public class DefaultSubscriptionRegistry extends AbstractSubscriptionRegistry {
 	protected void addSubscriptionInternal(
 			String sessionId, String subsId, String destination, Message<?> message) {
 
+		Expression expression = getSelectorExpression(message.getHeaders());
+		this.subscriptionRegistry.addSubscription(sessionId, subsId, destination, expression);
+		this.destinationCache.updateAfterNewSubscription(destination, sessionId, subsId);
+	}
+
+	@Nullable
+	private Expression getSelectorExpression(MessageHeaders headers) {
 		Expression expression = null;
-		MessageHeaders headers = message.getHeaders();
-		String selector = SimpMessageHeaderAccessor.getFirstNativeHeader(getSelectorHeaderName(), headers);
-		if (selector != null) {
-			try {
-				expression = this.expressionParser.parseExpression(selector);
-				this.selectorHeaderInUse = true;
-				if (logger.isTraceEnabled()) {
-					logger.trace("Subscription selector: [" + selector + "]");
+		if (getSelectorHeaderName() != null) {
+			String selector = SimpMessageHeaderAccessor.getFirstNativeHeader(getSelectorHeaderName(), headers);
+			if (selector != null) {
+				try {
+					expression = this.expressionParser.parseExpression(selector);
+					this.selectorHeaderInUse = true;
+					if (logger.isTraceEnabled()) {
+						logger.trace("Subscription selector: [" + selector + "]");
+					}
 				}
-			}
-			catch (Throwable ex) {
-				if (logger.isDebugEnabled()) {
-					logger.debug("Failed to parse selector: " + selector, ex);
+				catch (Throwable ex) {
+					if (logger.isDebugEnabled()) {
+						logger.debug("Failed to parse selector: " + selector, ex);
+					}
 				}
 			}
 		}
-		this.subscriptionRegistry.addSubscription(sessionId, subsId, destination, expression);
-		this.destinationCache.updateAfterNewSubscription(destination, sessionId, subsId);
+		return expression;
 	}
 
 	@Override

spring-messaging/src/main/java/org/springframework/messaging/simp/broker/SimpleBrokerMessageHandler.java

@@ -51,9 +51,6 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 
 	private static final byte[] EMPTY_PAYLOAD = new byte[0];
 
-	private final Map<String, SessionInfo> sessions = new ConcurrentHashMap<>();
-
-	private SubscriptionRegistry subscriptionRegistry;
 
 	@Nullable
 	private PathMatcher pathMatcher;
@@ -61,6 +58,9 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 	@Nullable
 	private Integer cacheLimit;
 
+	@Nullable
+	private String selectorHeaderName = "selector";
+
 	@Nullable
 	private TaskScheduler taskScheduler;
 
@@ -68,10 +68,15 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 	private long[] heartbeatValue;
 
 	@Nullable
-	private ScheduledFuture<?> heartbeatFuture;
+	private MessageHeaderInitializer headerInitializer;
+
+
+	private SubscriptionRegistry subscriptionRegistry;
+
+	private final Map<String, SessionInfo> sessions = new ConcurrentHashMap<>();
 
 	@Nullable
-	private MessageHeaderInitializer headerInitializer;
+	private ScheduledFuture<?> heartbeatFuture;
 
 
 	/**
@@ -102,6 +107,7 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 		this.subscriptionRegistry = subscriptionRegistry;
 		initPathMatcherToUse();
 		initCacheLimitToUse();
+		initSelectorHeaderNameToUse();
 	}
 
 	public SubscriptionRegistry getSubscriptionRegistry() {
@@ -149,6 +155,33 @@ public class SimpleBrokerMessageHandler extends AbstractBrokerMessageHandler {
 		}
 	}
 
+	/**
+	 * Configure the name of a header that a subscription message can have for
+	 * the purpose of filtering messages matched to the subscription. The header
+	 * value is expected to be a Spring EL boolean expression to be applied to
+	 * the headers of messages matched to the subscription.
+	 * <p>For example:
+	 * <pre>
+	 * headers.foo == 'bar'
+	 * </pre>
+	 * <p>By default this is set to "selector". You can set it to a different
+	 * name, or to {@code null} to turn off support for a selector header.
+	 * @param selectorHeaderName the name to use for a selector header
+	 * @since 4.3.17
+	 * @see #setSubscriptionRegistry
+	 * @see DefaultSubscriptionRegistry#setSelectorHeaderName(String)
+	 */
+	public void setSelectorHeaderName(@Nullable String selectorHeaderName) {
+		this.selectorHeaderName = selectorHeaderName;
+		initSelectorHeaderNameToUse();
+	}
+
+	private void initSelectorHeaderNameToUse() {
+		if (this.subscriptionRegistry instanceof DefaultSubscriptionRegistry) {
+			((DefaultSubscriptionRegistry) this.subscriptionRegistry).setSelectorHeaderName(this.selectorHeaderName);
+		}
+	}
+
 	/**
 	 * Configure the {@link org.springframework.scheduling.TaskScheduler} to
 	 * use for providing heartbeat support. Setting this property also sets the

spring-messaging/src/main/java/org/springframework/messaging/simp/config/SimpleBrokerRegistration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -36,6 +36,9 @@ public class SimpleBrokerRegistration extends AbstractBrokerRegistration {
 	@Nullable
 	private long[] heartbeat;
 
+	@Nullable
+	private String selectorHeaderName = "selector";
+
 
 	public SimpleBrokerRegistration(SubscribableChannel inChannel, MessageChannel outChannel, String[] prefixes) {
 		super(inChannel, outChannel, prefixes);
@@ -68,6 +71,24 @@ public class SimpleBrokerRegistration extends AbstractBrokerRegistration {
 		return this;
 	}
 
+	/**
+	 * Configure the name of a header that a subscription message can have for
+	 * the purpose of filtering messages matched to the subscription. The header
+	 * value is expected to be a Spring EL boolean expression to be applied to
+	 * the headers of messages matched to the subscription.
+	 * <p>For example:
+	 * <pre>
+	 * headers.foo == 'bar'
+	 * </pre>
+	 * <p>By default this is set to "selector". You can set it to a different
+	 * name, or to {@code null} to turn off support for a selector header.
+	 * @param selectorHeaderName the name to use for a selector header
+	 * @since 4.3.17
+	 */
+	public void setSelectorHeaderName(@Nullable String selectorHeaderName) {
+		this.selectorHeaderName = selectorHeaderName;
+	}
+
 
 	@Override
 	protected SimpleBrokerMessageHandler getMessageHandler(SubscribableChannel brokerChannel) {
@@ -79,6 +100,7 @@ public class SimpleBrokerRegistration extends AbstractBrokerRegistration {
 		if (this.heartbeat != null) {
 			handler.setHeartbeatValue(this.heartbeat);
 		}
+		handler.setSelectorHeaderName(this.selectorHeaderName);
 		return handler;
 	}
 

spring-messaging/src/test/java/org/springframework/messaging/simp/broker/DefaultSubscriptionRegistryTests.java

@@ -258,7 +258,7 @@ public class DefaultSubscriptionRegistryTests {
 	}
 
 	@Test
-	public void registerSubscriptionWithSelector() throws Exception {
+	public void registerSubscriptionWithSelector() {
 		String sessionId = "sess01";
 		String subscriptionId = "subs01";
 		String destination = "/foo";
@@ -266,6 +266,8 @@ public class DefaultSubscriptionRegistryTests {
 
 		this.registry.registerSubscription(subscribeMessage(sessionId, subscriptionId, destination, selector));
 
+		// First, try with selector header
+
 		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
 		accessor.setDestination(destination);
 		accessor.setNativeHeader("foo", "bar");
@@ -276,11 +278,34 @@ public class DefaultSubscriptionRegistryTests {
 		assertEquals(1, actual.size());
 		assertEquals(Collections.singletonList(subscriptionId), actual.get(sessionId));
 
+		// Then without
+
 		actual = this.registry.findSubscriptions(createMessage(destination));
 		assertNotNull(actual);
 		assertEquals(0, actual.size());
 	}
 
+	@Test
+	public void registerSubscriptionWithSelectorNotSupported() {
+		String sessionId = "sess01";
+		String subscriptionId = "subs01";
+		String destination = "/foo";
+		String selector = "headers.foo == 'bar'";
+
+		this.registry.setSelectorHeaderName(null);
+		this.registry.registerSubscription(subscribeMessage(sessionId, subscriptionId, destination, selector));
+
+		SimpMessageHeaderAccessor accessor = SimpMessageHeaderAccessor.create();
+		accessor.setDestination(destination);
+		accessor.setNativeHeader("foo", "bazz");
+		Message<?> message = MessageBuilder.createMessage("", accessor.getMessageHeaders());
+
+		MultiValueMap<String, String> actual = this.registry.findSubscriptions(message);
+		assertNotNull(actual);
+		assertEquals(1, actual.size());
+		assertEquals(Collections.singletonList(subscriptionId), actual.get(sessionId));
+	}
+
 	@Test  // SPR-11931
 	public void registerSubscriptionTwiceAndUnregister() {
 		this.registry.registerSubscription(subscribeMessage("sess01", "subs01", "/foo"));

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

@@ -383,6 +383,10 @@ class MessageBrokerBeanDefinitionParser implements BeanDefinitionParser {
 				String heartbeatValue = simpleBrokerElem.getAttribute("heartbeat");
 				brokerDef.getPropertyValues().add("heartbeatValue", heartbeatValue);
 			}
+			if (simpleBrokerElem.hasAttribute("selector-header")) {
+				String headerName = simpleBrokerElem.getAttribute("selector-header");
+				brokerDef.getPropertyValues().add("selectorHeaderName", headerName);
+			}
 		}
 		else if (brokerRelayElem != null) {
 			String prefix = brokerRelayElem.getAttribute("prefix");

spring-websocket/src/main/resources/org/springframework/web/socket/config/spring-websocket.xsd

@@ -384,6 +384,23 @@
                 ]]></xsd:documentation>
 			</xsd:annotation>
 		</xsd:attribute>
+		<xsd:attribute name="selector-header" type="xsd:string">
+			<xsd:annotation>
+				<xsd:documentation source="java:org.springframework.messaging.simp.stomp.SimpleBrokerMessageHandler"><![CDATA[
+	Configure the name of a header that a subscription message can have for
+	the purpose of filtering messages matched to the subscription. The header
+	value is expected to be a Spring EL boolean expression to be applied to
+	the headers of messages matched to the subscription.
+
+	For example:
+	headers.foo == 'bar'
+
+	By default this is set to "selector". You can set it to a different
+	name, or to "" to turn off support for a selector header.
+                ]]></xsd:documentation>
+			</xsd:annotation>
+		</xsd:attribute>
+
 	</xsd:complexType>
 
 	<xsd:complexType name="channel">

spring-websocket/src/test/java/org/springframework/web/socket/config/MessageBrokerBeanDefinitionParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -47,6 +47,7 @@ import org.springframework.messaging.handler.invocation.HandlerMethodArgumentRes
 import org.springframework.messaging.handler.invocation.HandlerMethodReturnValueHandler;
 import org.springframework.messaging.simp.SimpMessagingTemplate;
 import org.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler;
+import org.springframework.messaging.simp.broker.DefaultSubscriptionRegistry;
 import org.springframework.messaging.simp.broker.SimpleBrokerMessageHandler;
 import org.springframework.messaging.simp.stomp.StompBrokerRelayMessageHandler;
 import org.springframework.messaging.simp.user.DefaultUserDestinationResolver;
@@ -202,6 +203,8 @@ public class MessageBrokerBeanDefinitionParserTests {
 		assertNotNull(brokerMessageHandler);
 		Collection<String> prefixes = brokerMessageHandler.getDestinationPrefixes();
 		assertEquals(Arrays.asList("/topic", "/queue"), new ArrayList<>(prefixes));
+		DefaultSubscriptionRegistry registry = (DefaultSubscriptionRegistry) brokerMessageHandler.getSubscriptionRegistry();
+		assertEquals("my-selector", registry.getSelectorHeaderName());
 		assertNotNull(brokerMessageHandler.getTaskScheduler());
 		assertArrayEquals(new long[] {15000, 15000}, brokerMessageHandler.getHeartbeatValue());
 
@@ -228,7 +231,7 @@ public class MessageBrokerBeanDefinitionParserTests {
 
 		assertNotNull(this.appContext.getBean("webSocketScopeConfigurer", CustomScopeConfigurer.class));
 
-		DirectFieldAccessor accessor = new DirectFieldAccessor(brokerMessageHandler.getSubscriptionRegistry());
+		DirectFieldAccessor accessor = new DirectFieldAccessor(registry);
 		Object pathMatcher = accessor.getPropertyValue("pathMatcher");
 		String pathSeparator = (String) new DirectFieldAccessor(pathMatcher).getPropertyValue("pathSeparator");
 		assertEquals(".", pathSeparator);

spring-websocket/src/test/resources/org/springframework/web/socket/config/websocket-config-broker-simple.xml

@@ -35,7 +35,8 @@
 
 		<websocket:stomp-error-handler ref="errorHandler" />
 
-		<websocket:simple-broker prefix="/topic, /queue" heartbeat="15000,15000" scheduler="scheduler" />
+		<websocket:simple-broker prefix="/topic, /queue" selector-header="my-selector"
+				heartbeat="15000,15000" scheduler="scheduler" />
 
 	</websocket:message-broker>