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>26.1.5</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 BOM, add this to your dependencies:
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-pubsub</artifactId>
<version>1.121.1</version>
</dependency>
If you are using Gradle 5.x or later, add this to your dependencies:
implementation platform('com.google.cloud:libraries-bom:26.1.5')
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:1.122.1'If you are using SBT, add this to your dependencies:
libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.122.1"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 SDK 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 |
|---|---|---|
| Native Image Pub Sub Sample | source code |  |
| Publish Operations | source code | |
| Create Avro Schema Example | source code | |
| Create Big Query 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 Topic Example | source code | |
| Create Topic With Schema Example | source code | |
| Delete Schema Example | source code | |
| Delete Subscription Example | source code | |
| Delete Topic Example | source code | |
| Detach Subscription Example | source code | |
| Get Schema Example | source code | |
| Get Subscription Policy Example | source code | |
| Get Topic Policy 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 | |
| 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 | |
| Remove Dead Letter Policy Example | source code | |
| Resume Publish With Ordering Keys | source code | |
| Set Subscription Policy Example | source code | |
| Set Topic Policy Example | source code | |
| Subscribe Async Example | source code | |
| Subscribe Sync Example | source code | |
| Subscribe Sync With Lease Example | source code | |
| Subscribe With Avro Schema Example | source code | |
| Subscribe With Concurrency Control Example | source code | |
| Subscribe With Custom Attributes Example | source code | |
| Subscribe With Error Listener Example | source code | |
| Subscribe With Exactly Once Consumer With Response Example | source code | |
| Subscribe With Flow Control Settings Example | source code | |
| Subscribe With Proto Schema Example | source code | |
| Test Subscription Permissions Example | source code | |
| Test Topic Permissions Example | source code | |
| Update Dead Letter Policy Example | source code | |
| Update Push Configuration Example | source code | |
| State | source code | |
| State Proto | source code | |
To get help, follow the instructions in the shared Troubleshooting document.
Java 8 or above is required for using this client.
Google's Java client libraries, Google Cloud Client Libraries and Google Cloud API Libraries, follow the Oracle Java SE support roadmap (see the Oracle Java SE Product Releases section).
In general, new feature development occurs with support for the lowest Java LTS version covered by Oracle's Premier Support (which typically lasts 5 years from initial General Availability). If the minimum required JVM for a given library is changed, it is accompanied by a semver major release.
Java 11 and (in September 2021) Java 17 are the best choices for new development.
Google tests its client libraries with all current LTS versions covered by Oracle's Extended Support (which typically lasts 8 years from initial General Availability).
Google's client libraries support legacy versions of Java runtimes with long term stable libraries that don't receive feature updates on a best efforts basis as it may not be possible to backport all patches.
Google provides updates on a best efforts basis to apps that continue to use Java 7, though apps might need to upgrade to current versions of the library that supports their JVM.
The latest versions and the supported Java versions are identified on
the individual GitHub repository github.com/GoogleAPIs/java-SERVICENAME
and on google-cloud-java.
This library follows Semantic Versioning.
Contributions to this library are always welcome and highly encouraged.
See CONTRIBUTING for more information how to get started.
Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms. See Code of Conduct for more information.
Apache 2.0 - See LICENSE for more information.
| Java Version | Status |
|---|---|
| Java 8 |  |
| Java 8 OSX |  |
| Java 8 Windows |  |
| Java 11 |  |
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