KStream.split

As explained in Kafka Streams in Action, Second Edition

KStream.split is a Kafka Streams DSL method that begins branching a KStream and returns a BranchedKStream.

KStream.split begins branching a KStream and returns a BranchedKStream. Predicates route records into separate processing paths while preserving the original key and value types. section 6.6 section 6.6.2

Build a branching topology in four steps:

• Call split() on the source KStream. section 6.6.2
• Add each branch with branch(), a Predicate, and a Branched processor. section 6.6.2
• Finish with defaultBranch() to retain nonmatching records or noDefaultBranch() to drop them. section 6.6.2
• Collect returned KStream objects through the resulting map when branches need further topology work. section 6.6.2

Routing ZMart purchases

Predicate<String, Purchase> isCoffee = (key, purchase) -> purchase.getDepartment().equalsIgnoreCase("coffee"); Predicate<String, Purchase> isElectronics = (key, purchase) -> purchase.getDepartment().equalsIgnoreCase("electronics"); purchaseKStream.split() .branch(isCoffee, Branched.withConsumer(s -> s.to("coffee-topic"))) .branch(isElectronics, Branched.withConsumer(s -> s.to("electronics"))) .defaultBranch(Branched.withConsumer(s -> s.to("purchases"))); section 6.6

Figure 6.8 Creating branches for the two specific purchase types

Visualizes a single purchase stream dividing into branches for specific purchase types and a default path. section 6.6.2

How Kafka Streams in Action, Second Edition covers it

How deep it goes

Explains the split-branch-termination sequence, predicate gating, returned stream maps, and unchanged key-value types.

Examples

Uses ZMart coffee, electronics, and retail purchases, plus temperature and proximity sensor streams.

What it assumes

Assumes a KStream and predicate-based record processing, while teaching default and nondefault handling from the branching operation.

What you can do after

Apply it via the Kafka Streams DSL to route matching records to topics or reusable downstream KStreams.

How it connects

Connects KStream.split to BranchedKStream, branch, Predicate, Branched, defaultBranch, noDefaultBranch, and Kafka topics.

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Related concepts

• stream branchingproduces · Stream branching is the technique of dividing one record stream into multiple substreams according to predicates.
• BranchedKStreamproduces · BranchedKStream is a Kafka Streams object that defines and terminates branches created from a KStream.
• predicateuses · A predicate is a condition, expression, or function evaluated against an input or context to determine whether a specified criterion holds.
• KStream.mergeequivalent to · KStream.merge is a Kafka Streams DSL operator that combines multiple KStreams into one stream without guaranteeing ordering across input streams.

This explainer was generated by Manning's knowledge graph from the text of Kafka Streams in Action, Second Edition. The section links point to the parts of the book it draws on.