.. _streams_code_examples:

Code Examples
-------------

You can find Streams code examples in the Apache Kafka and Confluent GitHub repositories.

The Confluent Kafka Streams examples are located :cp-examples:`here|`. These examples demonstrate the use of Java 8 lambda expressions (which simplify the code significantly), show how to read/write Avro data, and how to implement end-to-end integration tests using embedded Kafka clusters.

The Apache Kafka Streams examples are located at :kafka-file:`https://github.com/apache/kafka/streams/examples/|streams/examples/src/main/java/org/apache/kafka/streams/examples`. These examples demonstrate the use of the :ref:`Kafka Streams DSL <streams_developer-guide_dsl>` and  the :ref:`low-level Processor API <streams_developer-guide_processor-api>`, including typed and untyped examples.

.. contents:: 
    :local:


Getting started examples
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Java
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With lambda expressions for Java 8+:

* :cp-examples:`WordCountLambdaExample|src/main/java/io/confluent/examples/streams/WordCountLambdaExample.java`
* :cp-examples:`AnomalyDetectionLambdaExample|src/main/java/io/confluent/examples/streams/AnomalyDetectionLambdaExample.java`
* :cp-examples:`GlobalKTablesExample|src/main/java/io/confluent/examples/streams/GlobalKTablesExample.java`
* :cp-examples:`MapFunctionLambdaExample|src/main/java/io/confluent/examples/streams/MapFunctionLambdaExample.java`
* :cp-examples:`PageViewRegionLambdaExample|src/main/java/io/confluent/examples/streams/PageViewRegionLambdaExample.java`
* :cp-examples:`UserRegionLambdaExample|src/main/java/io/confluent/examples/streams/UserRegionLambdaExample.java`
* :cp-examples:`WikipediaFeedAvroLambdaExample|src/main/java/io/confluent/examples/streams/WikipediaFeedAvroLambdaExample.java`

Without lambda expressions for Java 7+:

* :cp-examples:`PageViewRegionExample|src/main/java/io/confluent/examples/streams/PageViewRegionExample.java`
* :cp-examples:`WikipediaFeedAvroExample|src/main/java/io/confluent/examples/streams/WikipediaFeedAvroExample.java`

"""""
Scala
"""""

* :cp-examples:`MapFunctionScalaExample|src/main/scala/io/confluent/examples/streams/MapFunctionScalaExample.scala`


Security examples
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Java programming language
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Without lambda expressions for Java 7:

* :cp-examples:`SecureKafkaStreamsExample|src/main/java/io/confluent/examples/streams/SecureKafkaStreamsExample.java`


Interactive queries examples
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Since Confluent Platform 3.1+ and Kafka 0.10.1+, it is possible to query state stores created via the
:ref:`Kafka Streams DSL <streams_developer-guide_dsl>` and the
:ref:`Processor API <streams_developer-guide_processor-api>`.
Please refer to :ref:`Interactive Queries<streams_developer-guide_interactive-queries>` for further information.


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Java
""""

With lambda expressions for Java 8+:

* :cp-examples:`WordCountInteractiveQueriesExample|src/main/java/io/confluent/examples/streams/interactivequeries/WordCountInteractiveQueriesExample.java`
* :cp-examples:`KafkaMusicExample|src/main/java/io/confluent/examples/streams/interactivequeries/kafkamusic/KafkaMusicExample.java`


End-to-end application examples
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These demo applications use embedded instances of Kafka, ZooKeeper, and Confluent Schema Registry.  They are implemented as integration tests.

""""
Java
""""

With lambda expressions for Java 8+:

* :cp-examples:`WordCountLambdaIntegrationTest|src/test/java/io/confluent/examples/streams/WordCountLambdaIntegrationTest.java`
* :cp-examples:`FanoutLambdaIntegrationTest|src/test/java/io/confluent/examples/streams/FanoutLambdaIntegrationTest.java`
* :cp-examples:`GenericAvroIntegrationTest|src/test/java/io/confluent/examples/streams/GenericAvroIntegrationTest.java`
* :cp-examples:`GlobalKTablesExampleTest|src/test/java/io/confluent/examples/streams/GlobalKTablesExampleTest.java`
* :cp-examples:`HandlingCorruptedInputRecordsIntegrationTest|src/test/java/io/confluent/examples/streams/HandlingCorruptedInputRecordsIntegrationTest.java`
* :cp-examples:`MapFunctionLambdaIntegrationTest|src/test/java/io/confluent/examples/streams/MapFunctionLambdaIntegrationTest.java`
* :cp-examples:`MixAndMatchLambdaIntegrationTest|src/test/java/io/confluent/examples/streams/MixAndMatchLambdaIntegrationTest.java`
  -- how to mix the DSL and the Processor API
* :cp-examples:`SpecificAvroIntegrationTest|src/test/java/io/confluent/examples/streams/SpecificAvroIntegrationTest.java`
* :cp-examples:`StateStoresInTheDSLIntegrationTest|src/test/java/io/confluent/examples/streams/StateStoresInTheDSLIntegrationTest.java`
  -- how to use state stores in the DSL
* :cp-examples:`StreamToStreamJoinIntegrationTest|src/test/java/io/confluent/examples/streams/StreamToStreamJoinIntegrationTest.java`
* :cp-examples:`StreamToTableJoinIntegrationTest|src/test/java/io/confluent/examples/streams/StreamToTableJoinIntegrationTest.java`
* :cp-examples:`TableToTableJoinIntegrationTest|src/test/java/io/confluent/examples/streams/TableToTableJoinIntegrationTest.java`
* :cp-examples:`UserCountsPerRegionLambdaIntegrationTest|src/test/java/io/confluent/examples/streams/UserCountsPerRegionLambdaIntegrationTest.java`

Without lambda expressions for Java 7:

* :cp-examples:`PassThroughIntegrationTest|src/test/java/io/confluent/examples/streams/PassThroughIntegrationTest.java`

"""""
Scala
"""""

* :cp-examples:`StreamToTableJoinScalaIntegrationTest|src/test/scala/io/confluent/examples/streams/StreamToTableJoinScalaIntegrationTest.scala`
* :cp-examples:`ProbabilisticCountingScalaIntegrationTest|src/test/scala/io/confluent/examples/streams/ProbabilisticCountingScalaIntegrationTest.scala` - demonstrates how to probabilistically count items in an input stream by implementing a custom state store that is backed by a `Count-Min Sketch <https://en.wikipedia.org/wiki/Count%E2%80%93min_sketch>`__ data structure