Java idiomatic client for Pub/Sub Lite Kafka Shim.
If you are using Maven, add this to your pom.xml file:
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>pubsublite-kafka</artifactId>
<version>1.1.2</version>
</dependency>If you are using Gradle without BOM, add this to your dependencies:
implementation 'com.google.cloud:pubsublite-kafka:1.1.2'If you are using SBT, add this to your dependencies:
libraryDependencies += "com.google.cloud" % "pubsublite-kafka" % "1.1.2"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 Pub/Sub Lite Kafka Shim APIs, and the authenticated principal must have the IAM role(s) required to access GCP resources using the Pub/Sub Lite Kafka Shim API calls.
You will need a Google Cloud Platform Console project with the Pub/Sub Lite Kafka Shim API enabled.
You will need to enable billing to use Google Pub/Sub Lite Kafka Shim.
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 pubsublite-kafka library. See the Quickstart section
to add pubsublite-kafka as a dependency in your code.
Because Google Cloud Pub/Sub Lite provides partitioned zonal data storage with predefined capacity, a large portion of the Kafka Producer/Consumer API can be implemented using Pub/Sub Lite as a backend. The key differences are:
- Pub/Sub Lite does not support transactions. All transaction methods on
Producer<byte[], byte[]>will raise an exception. - Producers operate on a single topic, and Consumers on a single subscription.
- ProducerRecord may not specify partition explicitly.
- Consumers may not dynamically create consumer groups (subscriptions).
Note:
- In order to use Pub/Sub Lite seek operations, Consumers must have auto-commit enabled. Consumer seek methods are client-initiated, whereas Pub/Sub Lite seek operations are initiated out-of-band and pushed to Consumers. Both types of seeks should not be used concurrently, as they would interfere with one another.
With Pub/Sub Lite, you can use a Producer<byte[], byte[]> to publish messages:
import com.google.cloud.pubsublite.kafka.ProducerSettings;
import org.apache.kafka.clients.producer.*;
import com.google.cloud.pubsublite.*;
...
private final static String ZONE = "us-central1-b";
private final static Long PROJECT_NUM = 123L;
...
TopicPath topic = TopicPath.newBuilder()
.setLocation(CloudZone.parse(ZONE))
.setProject(ProjectNumber.of(PROJECT_NUM))
.setName(TopicName.of("my-topic")).build();
ProducerSettings settings = ProducerSettings.newBuilder()
.setTopicPath(topic)
.build();
try (Producer<byte[], byte[]> producer = settings.instantiate()) {
Future<RecordMetadata> sent = producer.send(new ProducerRecord(
topic.toString(), // Required to be the same topic.
"key".getBytes(),
"value".getBytes()
));
RecordMetadata meta = sent.get();
}With Pub/Sub Lite you can receive messages using a Consumer<byte[], byte[]>:
import com.google.cloud.pubsublite.kafka.ConsumerSettings;
import org.apache.kafka.clients.consumer.*;
import com.google.cloud.pubsublite.*;
import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
...
private final static String ZONE = "us-central1-b";
private final static Long PROJECT_NUM = 123L;
...
SubscriptionPath subscription = SubscriptionPath.newBuilder()
.setLocation(CloudZone.parse(ZONE))
.setProject(ProjectNumber.of(PROJECT_NUM))
.setName(SubscriptionName.of("my-sub"))
.build();
ConsumerSettings settings = ConsumerSettings.newBuilder()
.setSubscriptionPath(subscription)
.setPerPartitionFlowControlSettings(FlowControlSettings.builder()
.setBytesOutstanding(10_000_000) // 10 MB
.setMessagesOutstanding(Long.MAX_VALUE)
.build())
.setAutocommit(true);
try (Consumer<byte[], byte[]> consumer = settings.instantiate()) {
while (true) {
ConsumerRecords<byte[], byte[]> records = consumer.poll(Long.MAX_VALUE);
for (ConsumerRecord<byte[], byte[]> record : records) {
System.out.println(record.offset() + “: ” + record.value());
}
}
} catch (WakeupException e) {
// ignored
}Samples are in the samples/ directory.
| Sample | Source Code | Try it |
|---|---|---|
| Consumer Example | source code |  |
| Kafka Producer Example | source code | |
| Producer Example | source code | |
To get help, follow the instructions in the shared Troubleshooting document.
Pub/Sub Lite Kafka Shim uses gRPC for the transport layer.
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 |  |
Java is a registered trademark of Oracle and/or its affiliates.