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Release Notes

Releases

1.1.0 (2025-09-18)

BREAKING CHANGES

State Store Configuration (#136)

The store property in aggregate operations is now required.

Migration Required: 

# Before (1.0.8)
- type: aggregate
  initializer:
    expression: 0
    resultType: long
  aggregator:
    expression: aggregatedValue+1
    resultType: long

# After (1.1.0) - store is now required
- type: aggregate
  store:                    # REQUIRED
    type: window
    windowSize: 10m
    retention: 1h
  initializer:
    expression: 0
    resultType: long
  aggregator:
    expression: aggregatedValue+1
    resultType: long
See example: 09-example-aggregate.yaml

KEY NEW FEATURES

JsonSchema Support

Full JsonSchema support added for better data validation and schema management. Follows JSON Schema specification where missing additionalProperties defaults to true (allowing additional fields).

Tutorial: Working with JsonSchema Data

Notation and Schema Registry Configuration

New configuration system for data serialization and schema registries. Configure different implementations for each notation type (Avro, Protobuf, JsonSchema) and schema registry connections.

Tutorial: Working with JsonSchema Data Example: ksml-runner.yaml 

ksml:
  schemaRegistries:
    confluent:
      config:
        schema.registry.url: http://confluent-schema-registry:8081
    apicurio:
      config:
        apicurio.registry.url: http://apicurio-registry:8080

  notations:
    avro:
      type: confluent_avro
      schemaRegistry: confluent
    jsonschema:
      type: apicurio_json
      schemaRegistry: apicurio
    protobuf:
      type: apicurio_protobuf
      schemaRegistry: apicurio

Protobuf Support (BETA)

Added experimental Protocol Buffers support with both Confluent and Apicurio registry compatibility.

Example: 00-example-generate-sensordata-protobuf.yaml 

producers:
  sensordata_protobuf_producer:
    generator: generate_sensordata_message
    interval: 3s
    to:
      topic: ksml_sensordata_protobuf
      keyType: string
      valueType: protobuf:sensor_data  # New protobuf type

Enhanced Type System

  • List and Tuple Types (#285)
  • Map Type (#269)
  • Multiple message generation support for producers

Kubernetes & Monitoring

  • Helm Charts for production deployments (#85)
  • Kafka Streams Metrics Reporter with KSML tag enrichment
  • Health Probes: Separate liveness, readiness, and startup probes
  • NetworkPolicy and PrometheusRules support

IMPROVEMENTS

Syntax Enhancements (#133)

Enhanced "to" operation with clearer definitions. Both syntaxes continue to work: 

# Simple syntax (still supported)
to: my-topic

# Detailed syntax (recommended for clarity)
to:
  topic: my-topic
  keyType: string
  valueType: json

BUG FIXES

  • Fixed AVRO CharSequence crash with nested objects (#163)
  • Resolved excessive CPU usage issue (#157)
  • Fixed multiple join operation issues (#136, #143, #225)
  • Storage and state management improvements
  • Apicurio Registry 2.x compatibility

DOCUMENTATION & EXAMPLES

Improved Documentation with Docker Compose Examples

Updated KSML documentation with:

  • Working examples that run in Docker Compose
  • Step-by-step tutorials from beginner to advanced
  • Real-world use cases with complete implementations
  • Interactive testing - all examples can be run locally

Key Resources:

INFRASTRUCTURE UPDATES

  • Upgraded to Kafka 4.0.0 (#151)
  • Java 23 Security Manager support
  • Multi-architecture Docker builds (ARM64/AMD64)
  • Configurable GraalVM security options

1.0.8 (2025-06-20)

KSML

  • Axual header cleaning interceptor to KSML

Helm charts

  • Run as Job
  • Prometheus alert rules
  • Network policies

1.0.7 (2025-06-09)

  • Fix KSML crash when topic creation is needed and pattern configurations were provided

1.0.6 (2025-03-24)

  • Fix storage issues, Persistent Volumes always created and never cleaned
  • Fix slow and failing builds with multiple architectures

1.0.5 (2025-01-14)

  • Fix store serde regression

1.0.4 (2024-11-22)

  • Fix crash when using Avro CharSequence encodings and nested objects

1.0.3 (2024-10-18)

  • Fix high CPU usage
  • Upgrade to Avro 1.11.4 to fix CVE-2024-47561

1.0.2 (2024-09-20)

KSML

  • Upgrade to Kafka Streams 3.8.0
  • Avro Schema Registry settings no longer required if Avro not used
  • Add missing object in KSML Json Schema
  • Fix serialisation and list handling issues

Helm charts

  • Use liveness and readiness and startup probes to fix state issues
  • Fix conflicting default configuration Prometheus export and ServiceMonitor

1.0.1 (2024-07-17)

  • Topology Optimization can be applied
  • Runtime dependencies, like LZ4 compression support, are back in the KSML image
  • Fix parse error messages during join
  • Fix windowed aggregation flow errors
  • Update windowed object support in multiple operations and functions

1.0.0 (2024-06-28)

  • Reworked parsing logic, allowing alternatives for operations and other definitions to co-exist in the KSML language specification. This allows for better syntax checking in IDEs.
  • Lots of small fixes and completion modifications.

0.9.1 (2024-06-21)

  • Fix failing test in GitHub Actions during release
  • Unified build workflows

0.9.0 (2024-06-05)

  • Collectable metrics
  • New topology test suite
  • Python context hardening
  • Improved handling of Kafka tombstones
  • Added flexibility to producers (single shot, n-shot, or user condition-based)
  • JSON Logging support
  • Bumped GraalVM to 23.1.2
  • Bumped several dependency versions
  • Several fixes and security updates

0.8.0 (2024-03-08)

  • Reworked all parsing logic, to allow for exporting the JSON schema of the KSML specification:
    • docs/specification.md is now derived from internal parser logic, guaranteeing consistency and completeness.
    • examples/ksml.json contains the JSON schema, which can be loaded into IDEs for syntax validation and completion.
  • Improved schema handling:
    • Better compatibility checking between schema fields.
  • Improved support for state stores:
    • Update to state store typing and handling.
    • Manual state stores can be defined and referenced in pipelines.
    • Manual state stores are also available in Python functions.
    • State stores can be used 'side-effect-free' (e.g. no Avro schema registration)
  • Python function improvements:
    • Automatic variable assignment for state stores.
    • Every Python function can use a Java Logger, integrating Python output with KSML log output.
    • Type inference in situations where parameters or result types can be derived from the context.
  • Lots of small language updates:
    • Improve readability for store types, filter operations and windowing operations
    • Introduction of the "as" operation, which allows for pipeline referencing and chaining.
  • Better data type handling:
    • Separation of data types and KSML core, allowing for easier addition of new data types in the future.
    • Automatic conversion of data types, removing common pipeline failure scenarios.
    • New implementation for CSV handling.
  • Merged the different runners into a single runner.
    • KSML definitions can now include both producers (data generators) and pipelines (Kafka Streams topologies).
    • Removal of Kafka and Axual backend distinctions.
  • Configuration file updates, allowing for running multiple definitions in a single runner (each in its own namespace).
  • Examples updated to reflect the latest definition format.
  • Documentation updated.

0.2.2 (2024-01-30)

  • Fix KSML java process not stopping on exception
  • Fix stream-stream join validation and align other checks
  • Bump logback to 1.4.12
  • Fix to enable Streams optimisations to be applied to topology
  • Fix resolving admin client issues causing warning messages

0.2.1 (2023-12-20)

  • Fixed an issue with Avro and field validations

0.2.0 (2023-12-07)

  • Optimized Docker build
  • Merged KSML Runners into one module, optimize Docker builds and workflow
  • KSML documentation updates
  • Docker image, GraalPy venv, install and GU commands fail
  • Update GitHub Actions
  • Small robustness improvements
  • Issue #72 - Fix build failures when trying to use venv and install python packages
  • Manual state store support, Kafka client cleanups and configuration changes
  • Update and clean up dependencies
  • Update documentation to use new runner configurations
  • Update to GraalVM for JDK 21 Community

0.1.0 (2023-03-15)

  • Added XML/SOAP support
  • Added data generator
  • Added Automatic Type Conversion
  • Added Schema Support for XML, Avro, JSON, Schema
  • Added Basic Error Handling

0.0.4 (2022-12-02)

  • Update to Kafka 3.2.3
  • Update to Java 17
  • Support multiple architectures in KSML, linux/amd64 and linux/arm64
  • Refactored internal typing system, plus some fixes to store operations
  • Introduce queryable state stores
  • Add better handling of NULL keys and values from Kafka
  • Implement schema support
  • Added Docker multistage build
  • Bug fix for windowed objects
  • Store improvements
  • Support Liberica NIK
  • Switch from Travis CI to GitHub workflow
  • Build snapshot Docker image on pull request merged

0.0.3 (2021-07-30)

  • Support for Python 3 through GraalVM
  • improved data structuring
  • bug fixes

0.0.2 (2021-06-28)

  • Added JSON support, Named topology and name store supported

0.0.1 (2021-04-30)

  • First alpha release