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cheatsheet do
title 'KStreams'
docset_file_name 'KStreams'
keyword 'kstreams'
source_url 'http://cheat.kapeli.com'
category do
id "Terminal Nodes"
entry do
name '
```
print
```'
notes %|Output debugging style information to STDOUT. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#print--).|
end
entry do
name '
```
to
```'
notes %|Send output to Kafka topic.|
end
entry do
name '
```
foreach
```'
notes %|Consume data and discard results (useful if you're writing a kafka-to-* service). [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#foreach-org.apache.kafka.streams.kstream.ForeachAction-).|
end
entry do
name '
```
writeAsText
```'
notes %|Output debugging style information to FILE. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#writeAsText-java.lang.String-).|
end
end
category do
id 'Map' # Must be unique and is used as title of the category
entry do
name '
```
flatMap
```'
notes %|Iterator returns new object with new infor (both key and value can be altered, 0 or more records returned). [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#flatMap-org.apache.kafka.streams.kstream.KeyValueMapper-).|
end
entry do
name '
```
flatMapValue
```'
notes %|Iterator returns new value for same keys. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#flatMapValues-org.apache.kafka.streams.kstream.ValueMapper-).|
end
entry do
name '
```
map
```'
notes %|Iterator returns new object with new infor (both key and value can be altered, 0 or more records returned). [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#map-org.apache.kafka.streams.kstream.KeyValueMapper-).|
end
entry do
name '
```
mapValues
```'
notes %|Iterator returns new value for same keys. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#mapValues-org.apache.kafka.streams.kstream.ValueMapper-).|
end
end
category do
id 'Joins'
entry do
name '
```
join
```'
notes %|Joins two streams where key == key. Subclass ValueJoiner<V1, V2, R> to output joined object. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#join-org.apache.kafka.streams.kstream.GlobalKTable-org.apache.kafka.streams.kstream.KeyValueMapper-org.apache.kafka.streams.kstream.ValueJoiner-).|
end
entry do
name '
```
outerJoin
```'
notes %|Join but don't require BOTH streams to have record. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#outerJoin-org.apache.kafka.streams.kstream.KStream-org.apache.kafka.streams.kstream.ValueJoiner-org.apache.kafka.streams.kstream.JoinWindows-).|
end
entry do
name '
```
leftJoin
```'
notes %|If 'calling' or both streams have matching records, merge. If only "other" stream does, NOPE. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#leftJoin-org.apache.kafka.streams.kstream.GlobalKTable-org.apache.kafka.streams.kstream.KeyValueMapper-org.apache.kafka.streams.kstream.ValueJoiner-).|
end
end
category do
id 'Data Flow'
entry do
name '
```
filter
```'
notes %|If lambda function returns true, record proceeds into pipeline. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#filter-org.apache.kafka.streams.kstream.Predicate-).|
end
entry do
name '
```
selectKey
```'
notes %|Re-keys Kafka records. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#selectKey-org.apache.kafka.streams.kstream.KeyValueMapper-).|
end
entry do
name '
```
branch
```'
notes %|Takes a vargs of Predicates. Will return records outputted to the Predicate's topic. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#branch-org.apache.kafka.streams.kstream.Predicate...-).|
end
entry do
name '
```
through
```'
notes %|Produces to a topic. The resulting kstream will be a producer of that same topic. Could be used to reparition data. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#through-org.apache.kafka.common.serialization.Serde-org.apache.kafka.common.serialization.Serde-org.apache.kafka.streams.processor.StreamPartitioner-java.lang.String-).|
end
entry do
name '
```
transformValues
```'
notes %|Takes ValueTransformerSupplier, gets / sets StateStore. [Documentation](http://docs.confluent.io/current/streams/javadocs/org/apache/kafka/streams/kstream/KStream.html#transformValues-org.apache.kafka.streams.kstream.ValueTransformerSupplier-java.lang.String...-).|
end
end
end