com.google.cloud.pubsub.v1

Class Publisher

java.lang.Object

com.google.cloud.pubsub.v1.Publisher

public class Publisher
extends Object

A Cloud Pub/Sub publisher, that is associated with a specific topic at creation.

A Publisher provides built-in capabilities to automatically handle batching of messages, controlling memory utilization, and retrying API calls on transient errors.

With customizable options that control:

• Message batching: such as number of messages or max batch byte size.
• Retries: such as the maximum duration of retries for a failing batch of messages.

Publisher will use the credentials set on the channel, which uses application default credentials through GoogleCredentials.getApplicationDefault() by default.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Publisher.Builder A builder of Publishers.

Method Summary

Modifier and Type	Method and Description
static Publisher.Builder	defaultBuilder(com.google.pubsub.v1.TopicName topicName) Deprecated. Use newBuilder(TopicName) instead.
static long	getApiMaxRequestBytes() The maximum size of one request.
static long	getApiMaxRequestElementCount() The maximum number of messages in one request.
com.google.api.gax.batching.BatchingSettings	getBatchingSettings() The batching settings configured on this Publisher.
com.google.pubsub.v1.TopicName	getTopicName() Topic which the publisher publishes to.
static Publisher.Builder	newBuilder(com.google.pubsub.v1.TopicName topicName) Constructs a new Publisher.Builder using the given topic.
com.google.api.core.ApiFuture<String>	publish(com.google.pubsub.v1.PubsubMessage message) Schedules the publishing of a message.
void	shutdown() Schedules immediate publishing of any outstanding messages and waits until all are processed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getApiMaxRequestElementCount

public static long getApiMaxRequestElementCount()

The maximum number of messages in one request. Defined by the API.

getApiMaxRequestBytes

public static long getApiMaxRequestBytes()

The maximum size of one request. Defined by the API.

getTopicName

public com.google.pubsub.v1.TopicName getTopicName()

Topic which the publisher publishes to.

publish

public com.google.api.core.ApiFuture<String> publish(com.google.pubsub.v1.PubsubMessage message)

Schedules the publishing of a message. The publishing of the message may occur immediately or be delayed based on the publisher batching options.

Example of publishing a message.

 String message = "my_message";
 ByteString data = ByteString.copyFromUtf8(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);
   }
 });
 

Parameters:

message - the message to publish.

Returns:

the message ID wrapped in a future.

getBatchingSettings

public com.google.api.gax.batching.BatchingSettings getBatchingSettings()

The batching settings configured on this Publisher.

shutdown

public void shutdown()
              throws Exception

Schedules immediate publishing of any outstanding messages and waits until all are processed.

Sends remaining outstanding messages and prevents future calls to publish. This method should be invoked prior to deleting the Publisher object in order to ensure that no pending messages are lost.

Throws:

Exception

defaultBuilder

@Deprecated
public static Publisher.Builder defaultBuilder(com.google.pubsub.v1.TopicName topicName)

Deprecated. Use newBuilder(TopicName) instead.

Constructs a new Publisher.Builder using the given topic.

Example of creating a Publisher.

 String projectName = "my_project";
 String topicName = "my_topic";
 TopicName topic = TopicName.create(projectName, topicName);
 Publisher publisher = Publisher.newBuilder(topic).build();
 try {
   // ...
 } finally {
   // When finished with the publisher, make sure to shutdown to free up resources.
   publisher.shutdown();
 }
 

newBuilder

public static Publisher.Builder newBuilder(com.google.pubsub.v1.TopicName topicName)

Constructs a new Publisher.Builder using the given topic.

Example of creating a Publisher.

 String projectName = "my_project";
 String topicName = "my_topic";
 TopicName topic = TopicName.create(projectName, topicName);
 Publisher publisher = Publisher.newBuilder(topic).build();
 try {
   // ...
 } finally {
   // When finished with the publisher, make sure to shutdown to free up resources.
   publisher.shutdown();
 }