.readme-partials.yaml

custom_content: |
  #### Creating a topic

  With Pub/Sub you can create topics. A topic is a named resource to which messages are sent by
  publishers. Add the following imports at the top of your file:

  ```java
  import com.google.cloud.pubsub.v1.TopicAdminClient;
  import com.google.pubsub.v1.TopicName;
  ```
  Then, to create the topic, use the following code:

  ```java
  TopicName topic = TopicName.of("test-project", "test-topic");
  try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
    topicAdminClient.createTopic(topic);
  }
  ```

  #### Publishing messages

  With Pub/Sub you can publish messages to a topic. Add the following import at the top of your file:

  ```java
  import com.google.api.core.ApiFuture;
  import com.google.api.core.ApiFutureCallback;
  import com.google.api.core.ApiFutures;
  import com.google.cloud.pubsub.v1.Publisher;
  import com.google.common.util.concurrent.MoreExecutors;
  import com.google.protobuf.ByteString;
  import com.google.pubsub.v1.PubsubMessage;
  ```
  Then, to publish messages asynchronously, use the following code:

  ```java
  Publisher publisher = null;
  try {
    publisher = Publisher.newBuilder(topic).build();
    ByteString data = ByteString.copyFromUtf8("my-message");
    PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
    ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage);
    ApiFutures.addCallback(messageIdFuture, new ApiFutureCallback<String>() {
      public void onSuccess(String messageId) {
        System.out.println("published with message id: " + messageId);
      }

      public void onFailure(Throwable t) {
        System.out.println("failed to publish: " + t);
      }
    }, MoreExecutors.directExecutor());
    //...
  } finally {
    if (publisher != null) {
      publisher.shutdown();
      publisher.awaitTermination(1, TimeUnit.MINUTES);
    }
  }
  ```

  #### Creating a subscription

  With Pub/Sub you can create subscriptions. A subscription represents the stream of messages from a
  single, specific topic. Add the following imports at the top of your file:

  ```java
  import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
  import com.google.pubsub.v1.PushConfig;
  import com.google.pubsub.v1.SubscriptionName;
  import com.google.pubsub.v1.TopicName;
  ```
  Then, to create the subscription, use the following code:

  ```java
  TopicName topic = TopicName.of("test-project", "test-topic");
  SubscriptionName subscription = SubscriptionName.of("test-project", "test-subscription");

  try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
    subscriptionAdminClient.createSubscription(subscription, topic, PushConfig.getDefaultInstance(), 0);
  }
  ```

  #### Pulling messages

  With Pub/Sub you can pull messages from a subscription. Add the following imports at the top of your
  file:

  ```java
  import com.google.cloud.pubsub.v1.AckReplyConsumer;
  import com.google.cloud.pubsub.v1.MessageReceiver;
  import com.google.cloud.pubsub.v1.Subscriber;
  import com.google.common.util.concurrent.MoreExecutors;
  import com.google.pubsub.v1.PubsubMessage;
  import com.google.pubsub.v1.SubscriptionName;
  import com.google.pubsub.v1.TopicName;
  ```
  Then, to pull messages asynchronously, use the following code:

  ```java
  SubscriptionName subscription = SubscriptionName.of("test-project", "test-subscription");

  MessageReceiver receiver =
    new MessageReceiver() {
      @Override
      public void receiveMessage(PubsubMessage message, AckReplyConsumer consumer) {
        System.out.println("got message: " + message.getData().toStringUtf8());
        consumer.ack();
      }
    };

  Subscriber subscriber = null;
  try {
    subscriber = Subscriber.newBuilder(subscription.toString(), receiver).build();
    subscriber.addListener(
      new Subscriber.Listener() {
        @Override
        public void failed(Subscriber.State from, Throwable failure) {
          // Handle failure. This is called when the Subscriber encountered a fatal error and is shutting down.
          System.err.println(failure);
        }
      },
      MoreExecutors.directExecutor());
    subscriber.startAsync().awaitRunning();
    //...
  } finally {
    if (subscriber != null) {
      subscriber.stopAsync();
    }
  }
  ```
  #### Complete source code

  In [CreateTopicAndPublishMessages.java](https://github.com/googleapis/google-cloud-java/tree/master/google-cloud-examples/src/main/java/com/google/cloud/examples/pubsub/snippets/CreateTopicAndPublishMessages.java) and [CreateSubscriptionAndConsumeMessages.java](https://github.com/googleapis/google-cloud-java/tree/master/google-cloud-examples/src/main/java/com/google/cloud/examples/pubsub/snippets/CreateSubscriptionAndConsumeMessages.java) we put together all the code shown above into two programs. The programs assume that you are running on Compute Engine, App Engine Flexible or from your own desktop.