Fixs group must be configured for channel #2391

And delete rocketmq-comprehensive-example's consumer group configurations.

spring-cloud-alibaba-examples/rocketmq-example/rocketmq-comprehensive-example/src/main/resources/application.yml

@@ -18,7 +18,6 @@ spring:
           processor-out-0:
             producer:
               group: output_2
-
       bindings:
         producer-out-0:
           destination: num
@@ -26,10 +25,8 @@ spring:
           destination: square
         processor-in-0:
           destination: num
-          group: processor_group
         consumer-in-0:
           destination: square
-          group: consumer_group
 
 logging:
   level:

spring-cloud-alibaba-starters/spring-cloud-starter-stream-rocketmq/src/main/java/com/alibaba/cloud/stream/binder/rocketmq/RocketMQMessageChannelBinder.java

@@ -16,6 +16,9 @@
 
 package com.alibaba.cloud.stream.binder.rocketmq;
 
+import java.util.UUID;
+
+import com.alibaba.cloud.stream.binder.rocketmq.constant.RocketMQConst;
 import com.alibaba.cloud.stream.binder.rocketmq.custom.RocketMQBeanContainerCache;
 import com.alibaba.cloud.stream.binder.rocketmq.extend.ErrorAcknowledgeHandler;
 import com.alibaba.cloud.stream.binder.rocketmq.integration.inbound.RocketMQInboundChannelAdapter;
@@ -28,6 +31,7 @@ import com.alibaba.cloud.stream.binder.rocketmq.properties.RocketMQExtendedBindi
 import com.alibaba.cloud.stream.binder.rocketmq.properties.RocketMQProducerProperties;
 import com.alibaba.cloud.stream.binder.rocketmq.provisioning.RocketMQTopicProvisioner;
 import com.alibaba.cloud.stream.binder.rocketmq.utils.RocketMQUtils;
+import org.apache.rocketmq.common.protocol.NamespaceUtil;
 
 import org.springframework.cloud.stream.binder.AbstractMessageChannelBinder;
 import org.springframework.cloud.stream.binder.BinderSpecificPropertiesProvider;
@@ -48,6 +52,7 @@ import org.springframework.messaging.MessageHandler;
 import org.springframework.messaging.MessagingException;
 import org.springframework.util.StringUtils;
 
+
 /**
  * A {@link org.springframework.cloud.stream.binder.Binder} that uses RocketMQ as the
  * underlying middleware.
@@ -113,11 +118,17 @@ public class RocketMQMessageChannelBinder extends
 			String group,
 			ExtendedConsumerProperties<RocketMQConsumerProperties> extendedConsumerProperties)
 			throws Exception {
-		// todo support anymous consumer
-		if (!StringUtils.hasLength(group)) {
+		boolean anonymous = !StringUtils.hasLength(group);
+		/***
+		 * 	When using DLQ, at least the group property must be provided for proper naming of the DLQ destination
+		 *  According to https://docs.spring.io/spring-cloud-stream/docs/3.2.1/reference/html/spring-cloud-stream.html#spring-cloud-stream-reference
+		 */
+		if (anonymous && NamespaceUtil.isDLQTopic(destination.getName())) {
 			throw new RuntimeException(
-					"'group must be configured for channel " + destination.getName());
+					"group must be configured for DLQ" + destination.getName());
 		}
+		group = anonymous ? nextDefaultConsumerGroup() : group;
+
 		RocketMQUtils.mergeRocketMQProperties(binderConfigurationProperties,
 				extendedConsumerProperties.getExtension());
 		extendedConsumerProperties.getExtension().setGroup(group);
@@ -173,6 +184,14 @@ public class RocketMQMessageChannelBinder extends
 		};
 	}
 
+	/**
+	 * generate next default consumer group.
+	 * @return next default consumer group name.
+	 */
+	private static String nextDefaultConsumerGroup() {
+		return RocketMQConst.DEFAULT_GROUP + UUID.randomUUID().toString();
+	}
+
 	/**
 	 * Binders can return an {@link ErrorMessageStrategy} for building error messages;
 	 * binder implementations typically might add extra headers to the error message.
@@ -203,5 +222,4 @@ public class RocketMQMessageChannelBinder extends
 	public Class<? extends BinderSpecificPropertiesProvider> getExtendedPropertiesEntryClass() {
 		return this.extendedBindingProperties.getExtendedPropertiesEntryClass();
 	}
-
 }