KStreams

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Terminal Nodes

print

Output debugging style information to STDOUT. Documentation.

to

Send output to Kafka topic.

foreach

Consume data and discard results (useful if you're writing a kafka-to-* service). Documentation.

writeAsText

Output debugging style information to FILE. Documentation.

Map

flatMap

Iterator returns new object with new infor (both key and value can be altered, 0 or more records returned). Documentation.

flatMapValue

Iterator returns new value for same keys. Documentation.

map

Iterator returns new object with new infor (both key and value can be altered, 0 or more records returned). Documentation.

mapValues

Iterator returns new value for same keys. Documentation.

Joins

join

Joins two streams where key == key. Subclass ValueJoiner to output joined object. Documentation.

outerJoin

Join but don't require BOTH streams to have record. Documentation.

leftJoin

If 'calling' or both streams have matching records, merge. If only "other" stream does, NOPE. Documentation.

Data Flow

filter

If lambda function returns true, record proceeds into pipeline. Documentation.

selectKey

Re-keys Kafka records. Documentation.

branch

Takes a vargs of Predicates. Will return records outputted to the Predicate's topic. Documentation.

through

Produces to a topic. The resulting kstream will be a producer of that same topic. Could be used to reparition data. Documentation.

transformValues

Takes ValueTransformerSupplier, gets / sets StateStore. Documentation.