Class KafkaStreamsInteractiveQueryService

java.lang.Object

org.springframework.kafka.streams.KafkaStreamsInteractiveQueryService

public class KafkaStreamsInteractiveQueryService
extends Object

Provide a wrapper API around the interactive query stores in Kafka Streams. Using this API, an application can gain access to a named state store in the KafkaStreams under consideration.

Since:

3.2

Author:

Soby Chacko

Constructor Summary

Constructors

Constructor	Description
KafkaStreamsInteractiveQueryService(StreamsBuilderFactoryBean streamsBuilderFactoryBean)	Construct an instance for querying state stores from the KafkaStreams in the StreamsBuilderFactoryBean.

Method Summary

Modifier and Type	Method	Description
@Nullable org.apache.kafka.streams.state.HostInfo	getCurrentKafkaStreamsApplicationHostInfo()	Retrieve the current HostInfo where this Kafka Streams application is running on.
<K> org.apache.kafka.streams.state.HostInfo	getKafkaStreamsApplicationHostInfo(String store, K key, org.apache.kafka.common.serialization.Serializer<K> serializer)	Retrieve the HostInfo where the provided store and key are hosted on.
<T> T	retrieveQueryableStore(String storeName, org.apache.kafka.streams.state.QueryableStoreType<T> storeType)	Retrieve and return a queryable store by name created in the application.
void	setRetryTemplate(org.springframework.retry.support.RetryTemplate retryTemplate)	Custom RetryTemplate provided by the end users.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

KafkaStreamsInteractiveQueryService

public KafkaStreamsInteractiveQueryService(StreamsBuilderFactoryBean streamsBuilderFactoryBean)

Construct an instance for querying state stores from the KafkaStreams in the StreamsBuilderFactoryBean.

Parameters:

streamsBuilderFactoryBean - StreamsBuilderFactoryBean for KafkaStreams.

Method Details

setRetryTemplate

public void setRetryTemplate(org.springframework.retry.support.RetryTemplate retryTemplate)

Custom RetryTemplate provided by the end users.

Parameters:

retryTemplate - RetryTemplate

retrieveQueryableStore

public <T> T retrieveQueryableStore(String storeName,
 org.apache.kafka.streams.state.QueryableStoreType<T> storeType)

Retrieve and return a queryable store by name created in the application.

Type Parameters:

T - generic type for the queryable store

Parameters:

storeName - name of the queryable store

storeType - type of the queryable store

Returns:

queryable store.

getCurrentKafkaStreamsApplicationHostInfo

public @Nullable org.apache.kafka.streams.state.HostInfo getCurrentKafkaStreamsApplicationHostInfo()

Retrieve the current HostInfo where this Kafka Streams application is running on. This {link @HostInfo} is different from the Kafka `bootstrap.server` property, and is based on the Kafka Streams configuration property `application.server` where user-defined REST endpoints can be invoked per each Kafka Streams application instance. If this property - `application.server` - is not available from the end-user application, then null is returned.

Returns:

the current HostInfo

getKafkaStreamsApplicationHostInfo

public <K> org.apache.kafka.streams.state.HostInfo getKafkaStreamsApplicationHostInfo(String store,
 K key,
 org.apache.kafka.common.serialization.Serializer<K> serializer)

Retrieve the HostInfo where the provided store and key are hosted on. This may not be the current host that is running the application. Kafka Streams will look through all the consumer instances under the same application id and retrieves the proper host. Note that the end user applications must provide `application.server` as a configuration property for all the application instances when calling this method. If this is not available, then null maybe returned.

Type Parameters:

K - generic type for key

Parameters:

store - store name

key - key to look for

serializer - Serializer for the key

Returns:

the HostInfo where the key for the provided store is hosted currently