Kafka Streams

Client library for stream processing over Kafka topics with RocksDB local state.

Provider: default
Kind: Stream processor
Category: Messaging
Official docs: https://kafka.apache.org/documentation/streams/

Properties · 4 set by this component

property	type	values	required	kind default	this component
checkpointIntervalSeconds	integer	—	no	—	▸ 30
exactlyOnce	boolean	—	no	false	▸ false
instances	integer	—	no	—	inherited
lateDataPolicy	enum	drop \| shift \| sideline	no	—	inherited
managed	boolean	—	no	false	inherited
standbyReplicas · component property	integer	—	no	0	inherited
stateBackend	enum	memory \| rocksdb \| external	no	memory	▸ rocksdb
watermarkSeconds	integer	—	no	—	inherited
windowing	enum	none \| event-time \| processing-time	no	none	▸ event-time

Rules that apply · 1

Every rule whose selector covers this component's kind or its category. Whether a rule fires depends on the design: its properties, its edges and its groups.

Event-time windows without watermarkwarning

windowed-aggregation-without-watermark

Event-time windows need a watermark to know when a window is complete. Without one the processor either waits forever or closes windows early and silently drops late events.

— all of these hold:
— the node's `windowing` is "event-time"
— the node's `watermarkSeconds` has no value

Use it in a design

nodes:
  - { id: "kafka-streams", component: "kafka-streams" }

Other Stream processor products · 33

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Source

1# yaml-language-server: $schema=../../schema/component.schema.json
2# Kafka Streams: client library, event-time by record timestamp, RocksDB state with changelog topics,
3# processing.guarantee defaults to at_least_once and commits every 30 seconds.
4schemaVersion: "1"
5type: "component"
6id: "kafka-streams"
7kind: "stream-processor"
8provider: "default"
9docs: "https://kafka.apache.org/documentation/streams/"
10defaults:
11  windowing: "event-time"
12  checkpointIntervalSeconds: 30
13  exactlyOnce: false
14  stateBackend: "rocksdb"
15properties:
16  standbyReplicas:
17    type: "integer"
18    default: 0

The same page as markdown, for an agent: /catalogue/components/kafka-streams.md