Check out the docs at Apache Kafka web site: http://kafka.apache.org/0110/documentation/streams/

Sub-pages:

• Using Kafka Streams:
  • Usage Patterns
  • Application Reset Tool

  • Join Semantics

  • Streams FAQs
  • Data (Re)Processing Scenarios
• Development:
  • Development Plan
  • Discussions
  • Data (Re)Processing Scenarios
• Internals:
  
  • Data Management
  • Architecture

Find more links about Kafka Streams at Kafka Ecosystem page.

Kafka Streams related KIPs:

Adopted

• future release Kafka 1.0:
  • KIP-120: Cleanup Kafka Streams builder API
  • KIP 130: Expose states of active tasks to KafkaStreams public API
  • KIP-138: Change punctuate semantics
  • KIP-149: Enabling key access in ValueTransformer, ValueMapper, and ValueJoiner
  • KIP-150 - Kafka-Streams Cogroup
  • KIP 157 - Add consumer config options to streams reset tool
  • KIP-160: Augment KStream.print(), KStream.writeAsText() to allow users pass in extra parameters in the printed string
  • KIP-161: streams deserialization exception handlers
  • KIP-167: Add interface for the state store restoration process
  • KIP-173: Add prefix to StreamsConfig to enable setting default internal topic configs
• Kafka 0.11.0:
  • KIP-114: KTable state stores and improved semantics
  • KIP-123: Allow per stream/table timestamp extractor
  • KIP-121: Add KStream peek method
  • KIP-129: Streams Exactly-Once Semantics
  • KIP-134: Delay initial consumer group rebalance
  • KIP 155 - Add range scan for windowed state stores
  • KIP 156 Add option "dry run" to Streams application reset tool
• Kafka 0.10.2:
  • KIP-77: Improve Kafka Streams Join Semantics
  • KIP-90: Remove zkClient dependency from Streams
  • KIP-93: Improve invalid timestamp handling in Kafka Streams
  • KIP-94: Session Windows
  • KIP-97: Improved Kafka Client RPC Compatibility Policy 
  • KIP-99: Add Global Tables to Kafka Streams
  • KIP-100: Relax Type constraints in Kafka Streams API
  • KIP-104: Granular Sensors for Streams

• Kafka 0.10.1:

  • KIP-62: Allow consumer to send heartbeats from a background thread
  • KIP-63: Unify store and downstream caching in streams
  • KIP-67: Queryable state for Kafka Streams
  • KIP-71: Enable log compaction and deletion to co-exist
• Kafka 0.10.0:
  • KIP-28: Add a processor client
  • KIP-32: Add timestamps to Kafka message

Under discussion

• KIP-147: Add missing type parameters to StateStoreSupplier factories and KGroupedStream/Table methods
• KIP-159: Introducing Rich functions to Streams
• KIP-165: Extend Interactive Queries for return latest update timestamp per key
• KIP-171 - Extend Consumer Group Reset Offset for Stream Application
• KIP-182: Reduce Streams DSL overloads and allow easier use of custom storage engines

Inactive:

• KIP-95: Incremental Batch Processing for Kafka Streams

Discarded:

• KIP-116: Add State Store Checkpoint Interval Configuration
• KIP-132: Augment KStream.print to allow extra parameters in the printed string (duplicated by KIP-160)