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samples: add DLQ samples (#197)
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‎samples/install-without-bom/pom.xml‎

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<?xml version='1.0' encoding='UTF-8'?>
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<!--
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~ Copyright 2020 Google LLC
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~
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~ Licensed under the Apache License, Version 2.0 (the "License");
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~ you may not use this file except in compliance with the License.
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~ You may obtain a copy of the License at
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~
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~ http://www.apache.org/licenses/LICENSE-2.0
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~
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~ Unless required by applicable law or agreed to in writing, software
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~ distributed under the License is distributed on an "AS IS" BASIS,
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~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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~ See the License for the specific language governing permissions and
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~ limitations under the License.
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-->
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<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">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.google.cloud</groupId>

‎samples/pom.xml‎

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<?xml version='1.0' encoding='UTF-8'?>
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<!--
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~ Copyright 2020 Google LLC
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~
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~ Licensed under the Apache License, Version 2.0 (the "License");
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~ you may not use this file except in compliance with the License.
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~ You may obtain a copy of the License at
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~
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~ http://www.apache.org/licenses/LICENSE-2.0
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~
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~ Unless required by applicable law or agreed to in writing, software
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~ distributed under the License is distributed on an "AS IS" BASIS,
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~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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~ See the License for the specific language governing permissions and
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~ limitations under the License.
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-->
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<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">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.google.cloud</groupId>

‎samples/snapshot/pom.xml‎

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<?xml version='1.0' encoding='UTF-8'?>
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<!--
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~ Copyright 2020 Google LLC
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~
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~ Licensed under the Apache License, Version 2.0 (the "License");
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~ you may not use this file except in compliance with the License.
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~ You may obtain a copy of the License at
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~
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~ http://www.apache.org/licenses/LICENSE-2.0
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~
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~ Unless required by applicable law or agreed to in writing, software
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~ distributed under the License is distributed on an "AS IS" BASIS,
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~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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~ See the License for the specific language governing permissions and
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~ limitations under the License.
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-->
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<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">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.google.cloud</groupId>

‎samples/snippets/pom.xml‎

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<?xml version='1.0' encoding='UTF-8'?>
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<!--
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~ Copyright 2020 Google LLC
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~
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~ Licensed under the Apache License, Version 2.0 (the "License");
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~ you may not use this file except in compliance with the License.
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~ You may obtain a copy of the License at
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~
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~ http://www.apache.org/licenses/LICENSE-2.0
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~
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~ Unless required by applicable law or agreed to in writing, software
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~ distributed under the License is distributed on an "AS IS" BASIS,
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~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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~ See the License for the specific language governing permissions and
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~ limitations under the License.
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-->
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<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">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.google.cloud</groupId>

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

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/*
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* Copyright 2020 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package pubsub;
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// [START pubsub_dead_letter_create_subscription]
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import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
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import com.google.pubsub.v1.DeadLetterPolicy;
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import com.google.pubsub.v1.ProjectSubscriptionName;
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import com.google.pubsub.v1.ProjectTopicName;
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import com.google.pubsub.v1.Subscription;
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public class CreateSubscriptionWithDeadLetterPolicyExample {
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public static void main(String... args) throws Exception {
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// TODO(developer): Replace these variables before running the sample.
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String projectId = "Your Project ID";
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// This is the subscription you want to create with a dead letter policy.
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String subscriptionId = "Your Subscription ID";
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// This is an existing topic that you want to attach the subscription with dead letter policy
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// to.
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String topicId = "Your Topic ID";
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// This is an existing topic that the subscription with dead letter policy forwards dead letter
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// messages to.
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String deadLetterTopicId = "Your Dead Letter Topic ID";
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CreateSubscriptionWithDeadLetterPolicyExample.createSubscriptionWithDeadLetterPolicyExample(
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projectId, subscriptionId, topicId, deadLetterTopicId);
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}
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public static void createSubscriptionWithDeadLetterPolicyExample(
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String projectId, String subscriptionId, String topicId, String deadLetterTopicId)
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throws Exception {
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try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
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ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
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ProjectSubscriptionName subscriptionName =
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ProjectSubscriptionName.of(projectId, subscriptionId);
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ProjectTopicName deadLetterTopicName = ProjectTopicName.of(projectId, deadLetterTopicId);
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DeadLetterPolicy deadLetterPolicy =
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DeadLetterPolicy.newBuilder()
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.setDeadLetterTopic(deadLetterTopicName.toString())
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// The maximum number of times that the service attempts to deliver a
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// message before forwarding it to the dead letter topic. Must be [5-100].
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.setMaxDeliveryAttempts(10)
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.build();
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Subscription request =
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Subscription.newBuilder()
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.setName(subscriptionName.toString())
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.setTopic(topicName.toString())
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.setDeadLetterPolicy(deadLetterPolicy)
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.build();
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Subscription subscription = subscriptionAdminClient.createSubscription(request);
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System.out.println("Created subscription: " + subscription.getName());
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System.out.println(
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"It will forward dead letter messages to: "
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+ subscription.getDeadLetterPolicy().getDeadLetterTopic());
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System.out.println(
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"After "
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+ subscription.getDeadLetterPolicy().getMaxDeliveryAttempts()
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+ " delivery attempts.");
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// Remember to attach a subscription to the dead letter topic because
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// messages published to a topic with no subscriptions are lost.
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}
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}
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}
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// [END pubsub_dead_letter_create_subscription]

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

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/*
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* Copyright 2020 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package pubsub;
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// [START pubsub_dead_letter_delivery_attempt]
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import com.google.cloud.pubsub.v1.AckReplyConsumer;
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import com.google.cloud.pubsub.v1.MessageReceiver;
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import com.google.cloud.pubsub.v1.Subscriber;
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import com.google.pubsub.v1.ProjectSubscriptionName;
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import com.google.pubsub.v1.PubsubMessage;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.TimeoutException;
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public class ReceiveMessagesWithDeliveryAttemptsExample {
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public static void main(String... args) throws Exception {
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// TODO(developer): Replace these variables before running the sample.
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String projectId = "Your Project ID";
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// This is an existing subscription with a dead letter policy.
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String subscriptionId = "Your Subscription ID";
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ReceiveMessagesWithDeliveryAttemptsExample.receiveMessagesWithDeliveryAttemptsExample(
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projectId, subscriptionId);
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}
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public static void receiveMessagesWithDeliveryAttemptsExample(
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String projectId, String subscriptionId) {
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ProjectSubscriptionName subscriptionName =
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ProjectSubscriptionName.of(projectId, subscriptionId);
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// Instantiate an asynchronous message receiver.
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MessageReceiver receiver =
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new MessageReceiver() {
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@Override
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public void receiveMessage(PubsubMessage message, AckReplyConsumer consumer) {
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// Handle incoming message, then ack the received message.
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System.out.println("Id: " + message.getMessageId());
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System.out.println("Data: " + message.getData().toStringUtf8());
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System.out.println("Delivery Attempt: " + Subscriber.getDeliveryAttempt(message));
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consumer.ack();
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}
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};
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Subscriber subscriber = null;
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try {
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subscriber = Subscriber.newBuilder(subscriptionName, receiver).build();
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// Start the subscriber.
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subscriber.startAsync().awaitRunning();
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System.out.printf("Listening for messages on %s:\n", subscriptionName.toString());
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// Allow the subscriber to run for 30s unless an unrecoverable error occurs.
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subscriber.awaitTerminated(30, TimeUnit.SECONDS);
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} catch (TimeoutException timeoutException) {
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// Shut down the subscriber after 30s. Stop receiving messages.
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subscriber.stopAsync();
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}
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}
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}
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// [END pubsub_dead_letter_delivery_attempt]

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

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/*
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* Copyright 2020 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package pubsub;
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// [START pubsub_dead_letter_remove]
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import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
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import com.google.protobuf.FieldMask;
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import com.google.pubsub.v1.ProjectSubscriptionName;
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import com.google.pubsub.v1.Subscription;
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import com.google.pubsub.v1.TopicName;
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import com.google.pubsub.v1.UpdateSubscriptionRequest;
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public class RemoveDeadLetterPolicyExample {
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public static void main(String... args) throws Exception {
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// TODO(developer): Replace these variables before running the sample.
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String projectId = "Your Project ID";
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// This is an existing subscription with dead letter policy.
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String subscriptionId = "Your Subscription ID";
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// This is an existing topic that the subscription with dead letter policy is attached to.
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String topicId = "Your Topic ID";
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RemoveDeadLetterPolicyExample.removeDeadLetterPolicyExample(projectId, subscriptionId, topicId);
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}
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public static void removeDeadLetterPolicyExample(
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String projectId, String subscriptionId, String topicId) throws Exception {
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try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
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ProjectSubscriptionName subscriptionName =
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ProjectSubscriptionName.of(projectId, subscriptionId);
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TopicName topicName = TopicName.of(projectId, topicId);
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System.out.println(
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"Before: " + subscriptionAdminClient.getSubscription(subscriptionName).getAllFields());
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// Construct the subscription you expect to have after the request. Here,
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// values in the required fields (name, topic) help identify the subscription.
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// No dead letter policy is supplied.
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Subscription expectedSubscription =
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Subscription.newBuilder()
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.setName(subscriptionName.toString())
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.setTopic(topicName.toString())
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.build();
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// Construct a field mask to indicate which field to update in the subscription.
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FieldMask updateMask =
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FieldMask.newBuilder()
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.addPaths("dead_letter_policy.dead_letter_topic")
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// A default of 5 is applied upon successful update.
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.addPaths("dead_letter_policy.max_delivery_attempts")
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.build();
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UpdateSubscriptionRequest request =
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UpdateSubscriptionRequest.newBuilder()
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.setSubscription(expectedSubscription)
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.setUpdateMask(updateMask)
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.build();
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Subscription response = subscriptionAdminClient.updateSubscription(request);
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// You should see an empty dead letter topic field inside the dead letter policy.
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System.out.println("After: " + response.getAllFields());
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}
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}
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}
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// [END pubsub_dead_letter_remove]

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