Java idiomatic client for Cloud Pub/Sub.
If you are using Maven with BOM, add this to your pom.xml file:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>libraries-bom</artifactId>
<version>26.69.0</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-pubsub</artifactId>
</dependency>
</dependencies>
If you are using Maven without the BOM, add this to your dependencies:
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-pubsub</artifactId>
<version>1.141.5</version>
</dependency>
If you are using Gradle 5.x or later, add this to your dependencies:
implementation platform('com.google.cloud:libraries-bom:26.69.0')
implementation 'com.google.cloud:google-cloud-pubsub'
If you are using Gradle without BOM, add this to your dependencies:
implementation 'com.google.cloud:google-cloud-pubsub:1.142.0'
If you are using SBT, add this to your dependencies:
libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.142.0"
See the Authentication section in the base directory's README.
The client application making API calls must be granted authorization scopes required for the desired Cloud Pub/Sub APIs, and the authenticated principal must have the IAM role(s) required to access GCP resources using the Cloud Pub/Sub API calls.
You will need a Google Cloud Platform Console project with the Cloud Pub/Sub API enabled.
You will need to enable billing to use Google Cloud Pub/Sub.
Follow these instructions to get your project set up. You will also need to set up the local development environment by
installing the Google Cloud Command Line Interface and running the following commands in command line:
gcloud auth login
and gcloud config set project [YOUR PROJECT ID]
.
You'll need to obtain the google-cloud-pubsub
library. See the Quickstart section
to add google-cloud-pubsub
as a dependency in your code.
Cloud Pub/Sub is designed to provide reliable, many-to-many, asynchronous messaging between applications. Publisher applications can send messages to a topic and other applications can subscribe to that topic to receive the messages. By decoupling senders and receivers, Google Cloud Pub/Sub allows developers to communicate between independently written applications.
See the Cloud Pub/Sub client library docs to learn how to use this Cloud Pub/Sub Client Library.
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:
import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.pubsub.v1.TopicName;
Then, to create the topic, use the following code:
TopicName topic = TopicName.of("test-project", "test-topic");
try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
topicAdminClient.createTopic(topic);
}
With Pub/Sub you can publish messages to a topic. Add the following import at the top of your file:
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:
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);
}
}
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:
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:
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);
}
With Pub/Sub you can pull messages from a subscription. Add the following imports at the top of your file:
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:
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();
}
}
In CreateTopicAndPublishMessages.java and 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.
Samples are in the samples/
directory.
Sample | Source Code | Try it |
---|---|---|
Commit Avro Schema Example | source code | |
Commit Proto Schema Example | source code | |
Create Avro Schema Example | source code | |
Create Big Query Subscription Example | source code | |
Create Cloud Storage Subscription Example | source code | |
Create Proto Schema Example | source code | |
Create Pull Subscription Example | source code | |
Create Push Subscription Example | source code | |
Create Subscription With Dead Letter Policy Example | source code | |
Create Subscription With Exactly Once Delivery | source code | |
Create Subscription With Filtering | source code | |
Create Subscription With Ordering | source code | |
Create Subscription With Smt Example | source code | |
Create Topic Example | source code | |
Create Topic With Aws Msk Ingestion Example | source code | |
Create Topic With Azure Event Hubs Ingestion Example | source code | |
Create Topic With Cloud Storage Ingestion Example | source code | |
Create Topic With Confluent Cloud Ingestion Example | source code | |
Create Topic With Kinesis Ingestion Example | source code | |
Create Topic With Schema Example | source code | |
Create Topic With Schema Revisions Example | source code | |
Create Topic With Smt Example | source code | |
Create Unwrapped Push Subscription Example | source code | |
Delete Schema Example | source code | |
Delete Schema Revision Example | source code | |
Delete Subscription Example | source code | |
Delete Topic Example | source code | |
Detach Subscription Example | source code | |
Get Schema Example | source code | |
Get Schema Revision Example | source code | |
Get Subscription Policy Example | source code | |
Get Topic Policy Example | source code | |
List Schema Revisions Example | source code | |
List Schemas Example | source code | |
List Subscriptions In Project Example | source code | |
List Subscriptions In Topic Example | source code | |
List Topics Example | source code | |
Open Telemetry Publisher Example | source code | |
Open Telemetry Subscriber Example | source code | |
Optimistic Subscribe Example | source code | |
Publish Avro Records Example | source code | |
Publish Protobuf Messages Example | source code | |
Publish With Batch Settings Example | source code | |
Publish With Concurrency Control Example | source code | |
Publish With Custom Attributes Example | source code | |
Publish With Error Handler Example | source code | |
Publish With Flow Control Example | source code | |
Publish With Grpc Compression Example | source code | |
Publish With Ordering Keys | source code | |
Publish With Retry Settings Example | source code | |
Publisher Example | source code | |
Receive Messages With Delivery Attempts Example | source code |