samples: add DLQ samples

samples/install-without-bom/pom.xml

@@ -1,4 +1,19 @@
 <?xml version='1.0' encoding='UTF-8'?>
+<!--
+  ~ Copyright 2020 Google LLC
+  ~
+  ~ 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
+  ~
+  ~ http://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.
+  -->
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>

samples/pom.xml

@@ -1,4 +1,19 @@
 <?xml version='1.0' encoding='UTF-8'?>
+<!--
+  ~ Copyright 2020 Google LLC
+  ~
+  ~ 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
+  ~
+  ~ http://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.
+  -->
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>

samples/snapshot/pom.xml

@@ -1,4 +1,19 @@
 <?xml version='1.0' encoding='UTF-8'?>
+<!--
+  ~ Copyright 2020 Google LLC
+  ~
+  ~ 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
+  ~
+  ~ http://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.
+  -->
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>

samples/snippets/pom.xml

@@ -1,4 +1,19 @@
 <?xml version='1.0' encoding='UTF-8'?>
+<!--
+  ~ Copyright 2020 Google LLC
+  ~
+  ~ 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
+  ~
+  ~ http://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.
+  -->
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>

samples/snippets/src/main/java/pubsub/CreateSubscriptionWithDeadLetterPolicyExample.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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
+ *
+ * http://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 pubsub;
+
+// [START pubsub_dead_letter_create_subscription]
+
+import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
+import com.google.pubsub.v1.DeadLetterPolicy;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.ProjectTopicName;
+import com.google.pubsub.v1.Subscription;
+
+public class CreateSubscriptionWithDeadLetterPolicyExample {
+
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "Your Project ID";
+    // This is the subscription you want to create with a dead letter policy.
+    String subscriptionId = "Your Subscription ID";
+    // This is an existing topic that you want to attach the subscription with dead letter policy
+    // to.
+    String topicId = "Your Topic ID";
+    // This is an existing topic that the subscription with dead letter policy forwards dead letter
+    // messages to.
+    String deadLetterTopicId = "Your Dead Letter Topic ID";
+
+    CreateSubscriptionWithDeadLetterPolicyExample.createSubscriptionWithDeadLetterPolicyExample(
+        projectId, subscriptionId, topicId, deadLetterTopicId);
+  }
+
+  public static void createSubscriptionWithDeadLetterPolicyExample(
+      String projectId, String subscriptionId, String topicId, String deadLetterTopicId)
+      throws Exception {
+    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
+
+      ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
+      ProjectSubscriptionName subscriptionName =
+          ProjectSubscriptionName.of(projectId, subscriptionId);
+      ProjectTopicName deadLetterTopicName = ProjectTopicName.of(projectId, deadLetterTopicId);
+
+      DeadLetterPolicy deadLetterPolicy =
+          DeadLetterPolicy.newBuilder()
+              .setDeadLetterTopic(deadLetterTopicName.toString())
+              // The maximum number of times that the service attempts to deliver a
+              // message before forwarding it to the dead letter topic. Must be [5-100].
+              .setMaxDeliveryAttempts(10)
+              .build();
+
+      Subscription request =
+          Subscription.newBuilder()
+              .setName(subscriptionName.toString())
+              .setTopic(topicName.toString())
+              .setDeadLetterPolicy(deadLetterPolicy)
+              .build();
+
+      Subscription subscription = subscriptionAdminClient.createSubscription(request);
+
+      System.out.println("Created subscription: " + subscription.getName());
+      System.out.println(
+          "It will forward dead letter messages to: "
+              + subscription.getDeadLetterPolicy().getDeadLetterTopic());
+      System.out.println(
+          "After "
+              + subscription.getDeadLetterPolicy().getMaxDeliveryAttempts()
+              + " delivery attempts.");
+      // Remember to attach a subscription to the dead letter topic because
+      // messages published to a topic with no subscriptions are lost.
+    }
+  }
+}
+// [END pubsub_dead_letter_create_subscription]

samples/snippets/src/main/java/pubsub/ReceiveMessagesWithDeliveryAttemptsExample.java

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+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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
+ *
+ * http://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 pubsub;
+
+// [START pubsub_dead_letter_delivery_attempt]
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsub.v1.Subscriber;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.PubsubMessage;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+public class ReceiveMessagesWithDeliveryAttemptsExample {
+
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "Your Project ID";
+    // This is an existing subscription with a dead letter policy.
+    String subscriptionId = "Your Subscription ID";
+
+    ReceiveMessagesWithDeliveryAttemptsExample.receiveMessagesWithDeliveryAttemptsExample(
+        projectId, subscriptionId);
+  }
+
+  public static void receiveMessagesWithDeliveryAttemptsExample(
+      String projectId, String subscriptionId) {
+
+    ProjectSubscriptionName subscriptionName =
+        ProjectSubscriptionName.of(projectId, subscriptionId);
+
+    // Instantiate an asynchronous message receiver.
+    MessageReceiver receiver =
+        new MessageReceiver() {
+          @Override
+          public void receiveMessage(PubsubMessage message, AckReplyConsumer consumer) {
+            // Handle incoming message, then ack the received message.
+            System.out.println("Id: " + message.getMessageId());
+            System.out.println("Data: " + message.getData().toStringUtf8());
+            System.out.println("Delivery Attempt: " + Subscriber.getDeliveryAttempt(message));
+            consumer.ack();
+          }
+        };
+
+    Subscriber subscriber = null;
+    try {
+      subscriber = Subscriber.newBuilder(subscriptionName, receiver).build();
+      // Start the subscriber.
+      subscriber.startAsync().awaitRunning();
+      System.out.printf("Listening for messages on %s:\n", subscriptionName.toString());
+      // Allow the subscriber to run for 30s unless an unrecoverable error occurs.
+      subscriber.awaitTerminated(30, TimeUnit.SECONDS);
+    } catch (TimeoutException timeoutException) {
+      // Shut down the subscriber after 30s. Stop receiving messages.
+      subscriber.stopAsync();
+    }
+  }
+}
+// [END pubsub_dead_letter_delivery_attempt]

samples/snippets/src/main/java/pubsub/RemoveDeadLetterPolicyExample.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * 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
+ *
+ * http://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 pubsub;
+
+// [START pubsub_dead_letter_remove]
+
+import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
+import com.google.protobuf.FieldMask;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.Subscription;
+import com.google.pubsub.v1.TopicName;
+import com.google.pubsub.v1.UpdateSubscriptionRequest;
+
+public class RemoveDeadLetterPolicyExample {
+
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "Your Project ID";
+    // This is an existing subscription with dead letter policy.
+    String subscriptionId = "Your Subscription ID";
+    // This is an existing topic that the subscription with dead letter policy is attached to.
+    String topicId = "Your Topic ID";
+
+    RemoveDeadLetterPolicyExample.removeDeadLetterPolicyExample(projectId, subscriptionId, topicId);
+  }
+
+  public static void removeDeadLetterPolicyExample(
+      String projectId, String subscriptionId, String topicId) throws Exception {
+    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
+
+      ProjectSubscriptionName subscriptionName =
+          ProjectSubscriptionName.of(projectId, subscriptionId);
+      TopicName topicName = TopicName.of(projectId, topicId);
+
+      System.out.println(
+          "Before: " + subscriptionAdminClient.getSubscription(subscriptionName).getAllFields());
+
+      // Construct the subscription you expect to have after the request. Here,
+      // values in the required fields (name, topic) help identify the subscription.
+      // No dead letter policy is supplied.
+      Subscription expectedSubscription =
+          Subscription.newBuilder()
+              .setName(subscriptionName.toString())
+              .setTopic(topicName.toString())
+              .build();
+
+      // Construct a field mask to indicate which field to update in the subscription.
+      FieldMask updateMask =
+          FieldMask.newBuilder()
+              .addPaths("dead_letter_policy.dead_letter_topic")
+              // A default of 5 is applied upon successful update.
+              .addPaths("dead_letter_policy.max_delivery_attempts")
+              .build();
+
+      UpdateSubscriptionRequest request =
+          UpdateSubscriptionRequest.newBuilder()
+              .setSubscription(expectedSubscription)
+              .setUpdateMask(updateMask)
+              .build();
+
+      Subscription response = subscriptionAdminClient.updateSubscription(request);
+
+      // You should see an empty dead letter topic field inside the dead letter policy.
+      System.out.println("After: " + response.getAllFields());
+    }
+  }
+}
+// [END pubsub_dead_letter_remove]