```
public interface KafkaConsumerRebalanceListener
```
When implemented by a managed bean annotated with @Identifier and configured against an inbound connector, it will be applied as a consumer rebalance listener to that inbound connector's consumer.
To configure which listener you want to use, set the name in the inbound connector's consumer rebalance listener attribute. For example:
```
 mp.messaging.incoming.example.consumer-rebalance-listener.name=ExampleConsumerRebalanceListener

 @Identifier("ExampleConsumerRebalanceListener")
 public class ExampleConsumerRebalanceListener implements KafkaConsumerRebalanceListener {
     ...
 }
 
```
Alternatively, name your listener (using the @Identifier annotation) to be the group id used by the connector. For example:
```
 mp.messaging.incoming.example.group.id=my-group

 @Identifier("my-group")
 public class MyGroupConsumerRebalanceListener implements KafkaConsumerRebalanceListener {
     ...
 }
 
```
Setting the consumer rebalance listener name takes precedence over using the group id.
See Also:

ConsumerRebalanceListener

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method	Description
`default void`	`onPartitionsAssigned(org.apache.kafka.clients.consumer.Consumer<?,?> consumer, Collection<org.apache.kafka.common.TopicPartition> partitions)`	A callback method the user can implement to provide handling of customized offsets on completion of a successful partition re-assignment.
`default void`	`onPartitionsLost(org.apache.kafka.clients.consumer.Consumer<?,?> consumer, Collection<org.apache.kafka.common.TopicPartition> partitions)`	A callback method you can implement to provide handling of cleaning up resources for partitions that have already been reassigned to other consumers.
`default void`	`onPartitionsRevoked(org.apache.kafka.clients.consumer.Consumer<?,?> consumer, Collection<org.apache.kafka.common.TopicPartition> partitions)`	A callback method the user can implement to provide handling of offset commits to a customized store.

- Method Detail
  - onPartitionsAssigned
```
default void onPartitionsAssigned(org.apache.kafka.clients.consumer.Consumer<?,?> consumer,
                                  Collection<org.apache.kafka.common.TopicPartition> partitions)
```
    A callback method the user can implement to provide handling of customized offsets on completion of a successful partition re-assignment. This method will be called after the partition re-assignment completes and before the consumer starts fetching data, and only as the result of a poll(long) call.
    It is guaranteed that under normal conditions all the processes in a consumer group will execute their onPartitionsRevoked(Consumer, Collection) callback before any instance executes this callback. During exceptional scenarios, partitions may be migrated without the old owner being notified (i.e. their onPartitionsRevoked(Consumer, Collection) callback not triggered), and later when the old owner consumer realized this event, the onPartitionsLost(Consumer, Collection) (Collection)} callback will be triggered by the consumer then.
    It is common for the assignment callback to use the consumer instance in order to query offsets. It is possible for a WakeupException or InterruptException to be raised from one of these nested invocations. In this case, the exception will be propagated to the current invocation of KafkaConsumer.poll(java.time.Duration) in which this callback is being executed. This means it is not necessary to catch these exceptions and re-attempt to wakeup or interrupt the consumer thread. IMPORTANT: The behavior must be blocking. Callback invoked from the polling thread.
    
    Parameters:
    
    partitions - The list of partitions that are now assigned to the consumer (previously owned partitions will NOT be included, i.e. this list will only include newly added partitions)
    
    Throws:
    
    org.apache.kafka.common.errors.WakeupException - If raised from a nested call to KafkaConsumer
    
    org.apache.kafka.common.errors.InterruptException - If raised from a nested call to KafkaConsumer
  - onPartitionsRevoked
```
default void onPartitionsRevoked(org.apache.kafka.clients.consumer.Consumer<?,?> consumer,
                                 Collection<org.apache.kafka.common.TopicPartition> partitions)
```
    A callback method the user can implement to provide handling of offset commits to a customized store. This method will be called during a rebalance operation when the consumer has to give up some partitions. It can also be called when consumer is being closed (KafkaConsumer.close(Duration)) or is unsubscribing (KafkaConsumer.unsubscribe()). It is recommended that offsets should be committed in this callback to either Kafka or a custom offset store to prevent duplicate data.
    In eager rebalancing, it will always be called at the start of a rebalance and after the consumer stops fetching data. In cooperative rebalancing, it will be called at the end of a rebalance on the set of partitions being revoked iff the set is non-empty. For examples on usage of this API, see Usage Examples section of KafkaConsumer.
    It is common for the revocation callback to use the consumer instance in order to commit offsets. It is possible for a WakeupException or InterruptException to be raised from one of these nested invocations. In this case, the exception will be propagated to the current invocation of KafkaConsumer.poll(java.time.Duration) in which this callback is being executed. This means it is not necessary to catch these exceptions and re-attempt to wakeup or interrupt the consumer thread. IMPORTANT: The behavior must be blocking. Callback invoked from the polling thread.
    
    Parameters:
    
    partitions - The list of partitions that were assigned to the consumer and now need to be revoked (may not include all currently assigned partitions, i.e. there may still be some partitions left)
    
    Throws:
    
    org.apache.kafka.common.errors.WakeupException - If raised from a nested call to KafkaConsumer
    
    org.apache.kafka.common.errors.InterruptException - If raised from a nested call to KafkaConsumer
  - onPartitionsLost
```
default void onPartitionsLost(org.apache.kafka.clients.consumer.Consumer<?,?> consumer,
                              Collection<org.apache.kafka.common.TopicPartition> partitions)
```
    A callback method you can implement to provide handling of cleaning up resources for partitions that have already been reassigned to other consumers. This method will not be called during normal execution as the owned partitions would first be revoked by calling the onPartitionsRevoked(org.apache.kafka.clients.consumer.Consumer<?, ?>, java.util.Collection<org.apache.kafka.common.TopicPartition>), before being reassigned to other consumers during a rebalance event. However, during exceptional scenarios when the consumer realized that it does not own this partition any longer, i.e. not revoked via a normal rebalance event, then this method would be invoked.
    For example, this function is called if a consumer's session timeout has expired, or if a fatal error has been received indicating the consumer is no longer part of the group.
    By default it will just trigger onPartitionsRevoked(org.apache.kafka.clients.consumer.Consumer<?, ?>, java.util.Collection<org.apache.kafka.common.TopicPartition>); for users who want to distinguish the handling logic of revoked partitions v.s. lost partitions, they can override the default implementation.
    It is possible for a WakeupException or InterruptException to be raised from one of these nested invocations. In this case, the exception will be propagated to the current invocation of KafkaConsumer.poll(java.time.Duration) in which this callback is being executed. This means it is not necessary to catch these exceptions and re-attempt to wakeup or interrupt the consumer thread.
    
    Parameters:
    
    partitions - The list of partitions that were assigned to the consumer and now have been reassigned to other consumers. With the current protocol this will always include all of the consumer's previously assigned partitions, but this may change in future protocols (ie there would still be some partitions left)
    
    Throws:
    
    org.apache.kafka.common.errors.WakeupException - If raised from a nested call to KafkaConsumer
    
    org.apache.kafka.common.errors.InterruptException - If raised from a nested call to KafkaConsumer

Interface KafkaConsumerRebalanceListener

Method Summary

Method Detail

onPartitionsAssigned

onPartitionsRevoked

onPartitionsLost