Enable dead letter topic

daprdocs/content/en/java-sdk-docs/_index.md

@@ -178,6 +178,26 @@ public class SubscriberController {
     });
   }
 
+  /**
+   * Handles a registered publish endpoint on this app adding a topic which manage to forward undeliverable messages.
+   *
+   * @param cloudEvent The cloud event received.
+   * @return A message containing the time.
+   */
+  @Topic(name = "testingtopic", pubsubName = "${myAppProperty:messagebus}",
+      deadLetterTopic = "${deadLetterProperty:deadTopic}")
+  @PostMapping(path = "/testingtopic")
+  public Mono<Void> handleMessageWithErrorHandler(@RequestBody(required = false) CloudEvent<String> cloudEvent) {
+    return Mono.fromRunnable(() -> {
+      try {
+        System.out.println("Subscriber got: " + cloudEvent.getData());
+        System.out.println("Subscriber got: " + OBJECT_MAPPER.writeValueAsString(cloudEvent));
+      } catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+    });
+  }
+
   @Topic(name = "testingtopic", pubsubName = "${myAppProperty:messagebus}",
           rule = @Rule(match = "event.type == 'myevent.v2'", priority = 1))
   @PostMapping(path = "/testingtopicV2")

examples/src/main/java/io/dapr/examples/pubsub/http/SubscriberController.java

@@ -39,9 +39,10 @@ public class SubscriberController {
 
   private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
 
+
   /**
    * Handles a registered publish endpoint on this app.
-   * 
+   *
    * @param cloudEvent The cloud event received.
    * @return A message containing the time.
    */
@@ -58,6 +59,27 @@ public Mono<Void> handleMessage(@RequestBody(required = false) CloudEvent<String
     });
   }
 
+
+  /**
+   * Handles a registered publish endpoint on this app adding a topic which manage to forward undeliverable messages.
+   * 
+   * @param cloudEvent The cloud event received.
+   * @return A message containing the time.
+   */
+  @Topic(name = "testingtopic", pubsubName = "${myAppProperty:messagebus}",
+      deadLetterTopic = "${deadLetterProperty:deadTopic}")
+  @PostMapping(path = "/testingtopic")
+  public Mono<Void> handleMessageWithErrorHandler(@RequestBody(required = false) CloudEvent<String> cloudEvent) {
+    return Mono.fromRunnable(() -> {
+      try {
+        System.out.println("Subscriber got: " + cloudEvent.getData());
+        System.out.println("Subscriber got: " + OBJECT_MAPPER.writeValueAsString(cloudEvent));
+      } catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+    });
+  }
+
   /**
    * Handles a registered publish endpoint on this app (version 2 of a cloud
    * event).
@@ -66,6 +88,7 @@ public Mono<Void> handleMessage(@RequestBody(required = false) CloudEvent<String
    * @return A message containing the time.
    */
   @Topic(name = "testingtopic", pubsubName = "${myAppProperty:messagebus}",
+      deadLetterTopic = "${deadLetterProperty:deadTopic}",
           rule = @Rule(match = "event.type == \"v2\"", priority = 1))
   @PostMapping(path = "/testingtopicV2")
   public Mono<Void> handleMessageV2(@RequestBody(required = false) CloudEvent cloudEvent) {
@@ -84,7 +107,8 @@ public Mono<Void> handleMessageV2(@RequestBody(required = false) CloudEvent clou
    * @param cloudEvent The cloud event received.
    * @return A message containing the time.
    */
-  @Topic(name = "bulkpublishtesting", pubsubName = "${myAppProperty:messagebus}")
+  @Topic(name = "bulkpublishtesting", pubsubName = "${myAppProperty:messagebus}",
+      deadLetterTopic = "${deadLetterProperty:deadTopic}")
   @PostMapping(path = "/bulkpublishtesting")
   public Mono<Void> handleBulkPublishMessage(@RequestBody(required = false) CloudEvent cloudEvent) {
     return Mono.fromRunnable(() -> {
@@ -104,7 +128,8 @@ public Mono<Void> handleBulkPublishMessage(@RequestBody(required = false) CloudE
    * @return A list of responses for each event.
    */
   @BulkSubscribe()
-  @Topic(name = "testingtopicbulk", pubsubName = "${myAppProperty:messagebus}")
+  @Topic(name = "testingtopicbulk", pubsubName = "${myAppProperty:messagebus}",
+      deadLetterTopic = "${deadLetterProperty:deadTopic}")
   @PostMapping(path = "/testingtopicbulk")
   public Mono<BulkSubscribeAppResponse> handleBulkMessage(
       @RequestBody(required = false) BulkSubscribeMessage<CloudEvent<String>> bulkMessage) {

sdk-springboot/src/main/java/io/dapr/springboot/DaprBeanPostProcessor.java

@@ -107,6 +107,7 @@ private static void subscribeToTopics(
       Rule rule = topic.rule();
       String topicName = stringValueResolver.resolveStringValue(topic.name());
       String pubSubName = stringValueResolver.resolveStringValue(topic.pubsubName());
+      String deadLetterTopic = stringValueResolver.resolveStringValue(topic.deadLetterTopic());
       String match = stringValueResolver.resolveStringValue(rule.match());
       if ((topicName != null) && (topicName.length() > 0) && pubSubName != null && pubSubName.length() > 0) {
         try {
@@ -116,7 +117,7 @@ private static void subscribeToTopics(
           List<String> routes = getAllCompleteRoutesForPost(clazz, method, topicName);
           for (String route : routes) {
             daprRuntime.addSubscribedTopic(
-                pubSubName, topicName, match, rule.priority(), route, metadata, bulkSubscribe);
+                pubSubName, topicName, match, rule.priority(), route, deadLetterTopic, metadata, bulkSubscribe);
           }
         } catch (JsonProcessingException e) {
           throw new IllegalArgumentException("Error while parsing metadata: " + e);

sdk-springboot/src/main/java/io/dapr/springboot/DaprRuntime.java

@@ -22,6 +22,7 @@
  * Internal Singleton to handle Dapr configuration.
  */
 class DaprRuntime {
+
   /**
    * The singleton instance.
    */
@@ -33,8 +34,8 @@ class DaprRuntime {
   private final Map<DaprTopicKey, DaprSubscriptionBuilder> subscriptionBuilders = new HashMap<>();
 
   /**
-   * DaprRuntime should be used as a singleton, using {@link DaprRuntime#getInstance()}.
-   * The constructor's default scope is available for unit tests only.
+   * DaprRuntime should be used as a singleton, using {@link DaprRuntime#getInstance()}. The
+   * constructor's default scope is available for unit tests only.
    */
   private DaprRuntime() {
   }
@@ -60,38 +61,84 @@ public static DaprRuntime getInstance() {
    * Adds a topic to the list of subscribed topics.
    *
    * @param pubSubName PubSub name to subscribe to.
-   * @param topicName Name of the topic being subscribed to.
-   * @param match Match expression for this route.
-   * @param priority Priority for this match relative to others.
-   * @param route Destination route for requests.
-   * @param metadata Metadata for extended subscription functionality.
+   * @param topicName  Name of the topic being subscribed to.
+   * @param match      Match expression for this route.
+   * @param priority   Priority for this match relative to others.
+   * @param route      Destination route for requests.
+   * @param metadata   Metadata for extended subscription functionality.
    */
   public synchronized void addSubscribedTopic(String pubSubName,
                                               String topicName,
                                               String match,
                                               int priority,
                                               String route,
-                                              Map<String,String> metadata) {
+                                              Map<String, String> metadata) {
     this.addSubscribedTopic(pubSubName, topicName, match, priority, route, metadata, null);
   }
 
   /**
    * Adds a topic to the list of subscribed topics.
    *
-   * @param pubSubName PubSub name to subscribe to.
-   * @param topicName Name of the topic being subscribed to.
-   * @param match Match expression for this route.
-   * @param priority Priority for this match relative to others.
-   * @param route Destination route for requests.
-   * @param metadata Metadata for extended subscription functionality.
+   * @param pubSubName    PubSub name to subscribe to.
+   * @param topicName     Name of the topic being subscribed to.
+   * @param match         Match expression for this route.
+   * @param priority      Priority for this match relative to others.
+   * @param route         Destination route for requests.
+   * @param metadata      Metadata for extended subscription functionality.
    * @param bulkSubscribe Bulk subscribe configuration.
    */
   public synchronized void addSubscribedTopic(String pubSubName,
                                               String topicName,
                                               String match,
                                               int priority,
                                               String route,
-                                              Map<String,String> metadata,
+                                              Map<String, String> metadata,
+                                              DaprTopicBulkSubscribe bulkSubscribe) {
+    this.addSubscribedTopic(pubSubName, topicName, match, priority, route, null,
+        metadata, bulkSubscribe);
+  }
+
+  /**
+   * Adds a topic to the list of subscribed topics.
+   *
+   * @param pubSubName      PubSub name to subscribe to.
+   * @param topicName       Name of the topic being subscribed to.
+   * @param match           Match expression for this route.
+   * @param priority        Priority for this match relative to others.
+   * @param route           Destination route for requests.
+   * @param deadLetterTopic Name of topic to forward undeliverable messages.
+   * @param metadata        Metadata for extended subscription functionality.
+   */
+  public synchronized void addSubscribedTopic(String pubSubName,
+                                              String topicName,
+                                              String match,
+                                              int priority,
+                                              String route,
+                                              String deadLetterTopic,
+                                              Map<String, String> metadata) {
+    this.addSubscribedTopic(pubSubName, topicName, match, priority, route, deadLetterTopic,
+        metadata, null);
+  }
+
+  /**
+   * Adds a topic to the list of subscribed topics.
+   *
+   * @param pubSubName      PubSub name to subscribe to.
+   * @param topicName       Name of the topic being subscribed to.
+   * @param match           Match expression for this route.
+   * @param priority        Priority for this match relative to others.
+   * @param route           Destination route for requests.
+   * @param deadLetterTopic Name of topic to forward undeliverable messages.
+   * @param metadata        Metadata for extended subscription functionality.
+   * @param bulkSubscribe   Bulk subscribe configuration.
+   */
+  public synchronized void addSubscribedTopic(String pubSubName,
+                                              String topicName,
+                                              String match,
+                                              int priority,
+                                              String route,
+                                              String deadLetterTopic,
+                                              Map<String, String> metadata,
                                               DaprTopicBulkSubscribe bulkSubscribe) {
     DaprTopicKey topicKey = new DaprTopicKey(pubSubName, topicName);
 
@@ -111,14 +158,18 @@ public synchronized void addSubscribedTopic(String pubSubName,
       builder.setMetadata(metadata);
     }
 
+    if (deadLetterTopic != null && !deadLetterTopic.isEmpty()) {
+      builder.setDeadLetterTopic(deadLetterTopic);
+    }
+
     if (bulkSubscribe != null) {
       builder.setBulkSubscribe(bulkSubscribe);
     }
   }
 
   public synchronized DaprTopicSubscription[] listSubscribedTopics() {
     List<DaprTopicSubscription> values = subscriptionBuilders.values().stream()
-            .map(b -> b.build()).collect(Collectors.toList());
+        .map(b -> b.build()).collect(Collectors.toList());
     return values.toArray(new DaprTopicSubscription[0]);
   }
 }

sdk-springboot/src/main/java/io/dapr/springboot/DaprSubscriptionBuilder.java

@@ -21,65 +21,91 @@
 import java.util.stream.Collectors;
 
 class DaprSubscriptionBuilder {
+
   private final String pubsubName;
   private final String topic;
   private final List<TopicRule> rules;
+  private String deadLetterTopic;
   private String defaultPath;
   private Map<String, String> metadata;
 
   private DaprTopicBulkSubscribe bulkSubscribe;
 
   /**
    * Create a subscription topic.
+   *
    * @param pubsubName The pubsub name to subscribe to.
-   * @param topic The topic to subscribe to.
+   * @param topic      The topic to subscribe to.
    */
   DaprSubscriptionBuilder(String pubsubName, String topic) {
     this.pubsubName = pubsubName;
     this.topic = topic;
     this.rules = new ArrayList<>();
+    this.deadLetterTopic = null;
     this.defaultPath = null;
     this.metadata = Collections.emptyMap();
   }
 
   /**
    * Sets the default path for the subscription.
+   *
    * @param path The default path.
    * @return this instance.
    */
   DaprSubscriptionBuilder setDefaultPath(String path) {
     if (defaultPath != null) {
       if (!defaultPath.equals(path)) {
         throw new RuntimeException(
-                String.format(
-                        "a default route is already set for topic %s on pubsub %s (current: '%s', supplied: '%s')",
-                        this.topic, this.pubsubName, this.defaultPath, path));
+            String.format(
+                "a default route is already set for topic %s on pubsub %s (current: '%s', supplied: '%s')",
+                this.topic, this.pubsubName, this.defaultPath, path));
       }
     }
     defaultPath = path;
     return this;
   }
 
+  /**
+   * Sets the dead letter topic for the subscription.
+   *
+   * @param deadLetterTopic Name of dead letter topic.
+   * @return this instance.
+   */
+  DaprSubscriptionBuilder setDeadLetterTopic(String deadLetterTopic) {
+    if (this.deadLetterTopic != null) {
+      if (!this.deadLetterTopic.equals(deadLetterTopic)) {
+        throw new RuntimeException(
+            String.format(
+                "a default dead letter topic is already set for topic %s on pubsub %s (current: '%s', supplied: '%s')",
+                this.topic, this.pubsubName, this.deadLetterTopic, deadLetterTopic));
+      }
+    }
+    this.deadLetterTopic = deadLetterTopic;
+    return this;
+  }
+
   /**
    * Adds a rule to the subscription.
-   * @param path The path to route to.
-   * @param match The CEL expression the event must match.
+   *
+   * @param path     The path to route to.
+   * @param match    The CEL expression the event must match.
    * @param priority The priority of the rule.
    * @return this instance.
    */
   public DaprSubscriptionBuilder addRule(String path, String match, int priority) {
     if (rules.stream().anyMatch(e -> e.getPriority() == priority)) {
       throw new RuntimeException(
-              String.format(
-                      "a rule priority of %d is already used for topic %s on pubsub %s",
-                      priority, this.topic, this.pubsubName));
+          String.format(
+              "a rule priority of %d is already used for topic %s on pubsub %s",
+              priority, this.topic, this.pubsubName));
     }
     rules.add(new TopicRule(path, match, priority));
     return this;
   }
 
   /**
    * Sets the metadata for the subscription.
+   *
    * @param metadata The metadata.
    * @return this instance.
    */
@@ -90,6 +116,7 @@ public DaprSubscriptionBuilder setMetadata(Map<String, String> metadata) {
 
   /**
    * Sets the bulkSubscribe configuration for the subscription.
+   *
    * @param bulkSubscribe The bulk subscribe configuration.
    * @return this instance.
    */
@@ -100,6 +127,7 @@ public DaprSubscriptionBuilder setBulkSubscribe(DaprTopicBulkSubscribe bulkSubsc
 
   /**
    * Builds the DaprTopicSubscription that is returned by the application to Dapr.
+   *
    * @return The DaprTopicSubscription.
    */
   public DaprTopicSubscription build() {
@@ -109,16 +137,19 @@ public DaprTopicSubscription build() {
     if (!rules.isEmpty()) {
       Collections.sort(rules, Comparator.comparingInt(TopicRule::getPriority));
       List<DaprTopicRule> topicRules = rules.stream()
-              .map(e -> new DaprTopicRule(e.match, e.path)).collect(Collectors.toList());
+          .map(e -> new DaprTopicRule(e.match, e.path)).collect(Collectors.toList());
       routes = new DaprTopicRoutes(topicRules, defaultPath);
     } else {
       route = defaultPath;
     }
 
-    return new DaprTopicSubscription(this.pubsubName, this.topic, route, routes, metadata, bulkSubscribe);
+    return new DaprTopicSubscription(this.pubsubName, this.topic, route, this.deadLetterTopic,
+        routes, metadata,
+        bulkSubscribe);
   }
 
   private static class TopicRule {
+
     private final String path;
     private final String match;
     private final int priority;