Pulsar adaptor for Apache Kafka

Pulsar provides an easy option for applications that are currently written using the Apache Kafka Java client API.

Using the Pulsar Kafka compatibility wrapper

In an existing application, change the regular Kafka client dependency and replace it with the Pulsar Kafka wrapper:



Include dependency for Pulsar Kafka wrapper:


With the new dependency, the existing code should work without any changes. The only thing that needs to be adjusted is the configuration, to make sure to point the producers and consumers to Pulsar service rather than Kafka and to use a particular Pulsar topic.

Producer example

// Topic needs to be a regular Pulsar topic
String topic = "persistent://sample/standalone/ns/my-topic";

Properties props = new Properties();
// Point to a Pulsar service
props.put("bootstrap.servers", "pulsar://localhost:6650");

props.put("key.serializer", IntegerSerializer.class.getName());
props.put("value.serializer", StringSerializer.class.getName());

Producer<Integer, String> producer = new KafkaProducer<>(props);

for (int i = 0; i < 10; i++) {
    producer.send(new ProducerRecord<Integer, String>(topic, i, "hello-" + i));
    log.info("Message {} sent successfully", i);


Consumer example

String topic = "persistent://sample/standalone/ns/my-topic";

Properties props = new Properties();
// Point to a Pulsar service
props.put("bootstrap.servers", "pulsar://localhost:6650");
props.put("group.id", "my-subscription-name");
props.put("enable.auto.commit", "false");
props.put("key.deserializer", IntegerDeserializer.class.getName());
props.put("value.deserializer", StringDeserializer.class.getName());

Consumer<Integer, String> consumer = new KafkaConsumer<>(props);

while (true) {
    ConsumerRecords<Integer, String> records = consumer.poll(100);
    records.forEach(record -> {
        log.info("Received record: {}", record);

    // Commit last offset

Complete Examples

You can find the complete producer and consumer examples here.

Compatibility matrix

Currently the Pulsar Kafka wrapper supports most of the operations offered by the Kafka API.



Producer Method Supported Notes
Future<RecordMetadata> send(ProducerRecord<K, V> record) Yes Currently no support for explicitly set the partition id when publishing
Future<RecordMetadata> send(ProducerRecord<K, V> record, Callback callback) Yes  
void flush() Yes  
List<PartitionInfo> partitionsFor(String topic) No  
Map<MetricName, ? extends Metric> metrics() No  
void close() Yes  
void close(long timeout, TimeUnit unit) Yes  


Config property Supported Notes
acks Ignored Durability and quorum writes are configured at the namespace level
batch.size Ignored  
block.on.buffer.full Yes If true it will block producer, otherwise give error
bootstrap.servers Yes Needs to point to a single Pulsar service URL
buffer.memory Ignored  
client.id Ignored  
compression.type Yes Allows gzip and lz4. No snappy.
connections.max.idle.ms Ignored  
interceptor.classes Ignored  
key.serializer Yes  
linger.ms Yes Controls the group commit time when batching messages
max.block.ms Ignored  
max.in.flight.requests.per.connection Ignored In Pulsar ordering is maintained even with multiple requests in flight
max.request.size Ignored  
metric.reporters Ignored  
metrics.num.samples Ignored  
metrics.sample.window.ms Ignored  
partitioner.class Ignored  
receive.buffer.bytes Ignored  
reconnect.backoff.ms Ignored  
request.timeout.ms Ignored  
retries Ignored Pulsar client retries with exponential backoff until the send timeout expires
send.buffer.bytes Ignored  
timeout.ms Ignored  
value.serializer Yes  



Consumer Method Supported Notes
Set<TopicPartition> assignment() No  
Set<String> subscription() Yes  
void subscribe(Collection<String> topics) Yes  
void subscribe(Collection<String> topics, ConsumerRebalanceListener callback) No  
void assign(Collection<TopicPartition> partitions) No  
void subscribe(Pattern pattern, ConsumerRebalanceListener callback) No  
void unsubscribe() Yes  
ConsumerRecords<K, V> poll(long timeoutMillis) Yes  
void commitSync() Yes  
void commitSync(Map<TopicPartition, OffsetAndMetadata> offsets) Yes  
void commitAsync() Yes  
void commitAsync(OffsetCommitCallback callback) Yes  
void commitAsync(Map<TopicPartition, OffsetAndMetadata> offsets, OffsetCommitCallback callback) Yes  
void seek(TopicPartition partition, long offset) No  
void seekToBeginning(Collection<TopicPartition> partitions) No  
void seekToEnd(Collection<TopicPartition> partitions) No  
long position(TopicPartition partition) Yes  
OffsetAndMetadata committed(TopicPartition partition) Yes  
Map<MetricName, ? extends Metric> metrics() No  
List<PartitionInfo> partitionsFor(String topic) No  
Map<String, List<PartitionInfo>> listTopics() No  
Set<TopicPartition> paused() No  
void pause(Collection<TopicPartition> partitions) No  
void resume(Collection<TopicPartition> partitions) No  
Map<TopicPartition, OffsetAndTimestamp> offsetsForTimes(Map<TopicPartition, Long> timestampsToSearch) No  
Map<TopicPartition, Long> beginningOffsets(Collection<TopicPartition> partitions) No  
Map<TopicPartition, Long> endOffsets(Collection<TopicPartition> partitions) No  
void close() Yes  
void close(long timeout, TimeUnit unit) Yes  
void wakeup() No  


Config property Supported Notes
group.id Yes Maps to a Pulsar subscription name
max.poll.records Ignored  
max.poll.interval.ms Ignored Messages are “pushed” from broker
session.timeout.ms Ignored  
heartbeat.interval.ms Ignored  
bootstrap.servers Yes Needs to point to a single Pulsar service URL
enable.auto.commit Yes  
auto.commit.interval.ms Ignored With auto-commit, acks are sent immediately to broker
partition.assignment.strategy Ignored  
auto.offset.reset Ignored  
fetch.min.bytes Ignored  
fetch.max.bytes Ignored  
fetch.max.wait.ms Ignored  
metadata.max.age.ms Ignored  
max.partition.fetch.bytes Ignored  
send.buffer.bytes Ignored  
receive.buffer.bytes Ignored  
client.id Ignored  

Custom Pulsar configurations

You can configure Pulsar authentication provider directly from the Kafka properties.


Config property Default Notes
pulsar.authentication.class   Configure to auth provider. Eg. org.apache.pulsar.client.impl.auth.AuthenticationTls
pulsar.use.tls false Enable TLS transport encryption
pulsar.tls.trust.certs.file.path   Path for the TLS trust certificate store
pulsar.tls.allow.insecure.connection false Accept self-signed certificates from brokers