CloudEvents Kotlin SDK

A CNCF project — part of the CloudEvents ecosystem.

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What It Is

A Kotlin Multiplatform SDK for CloudEvents, the CNCF-governed specification for describing event data in a common way. The SDK provides a type-safe, idiomatic Kotlin API for composing, validating, encoding, and decoding CloudEvents across JVM, JavaScript, WebAssembly, and native platforms.

The :core module is a pure-Kotlin, stdlib-only library with no JVM-specific dependencies — it compiles on every supported Kotlin Multiplatform target from a single shared source set.

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Version Support Policy

This SDK supports CloudEvents v1.0 (latest spec text 1.0.2, honoring 1.0.1 clarifications) and v0.3 per the CloudEvents SDK support policy special case.

The CloudEvents SDK support policy requires each SDK to support the latest major spec version (currently v1.0) and, while v1.0 is the latest, also v0.3. Within a major version only the latest minor text is tracked — there is no runtime toggle between v1.0.1 and v1.0.2; both carry the "1.0" specversion value.

For the authoritative policy definition, see: cloudevents/spec — SDK Requirements

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Modules

Module	Status	Description
:core	Active	CloudEvent data model, type system, attribute validation, and Message-SPI interfaces. Stdlib-only, no third-party runtime dependencies.
Format modules (JSON, Avro, Protobuf)	Planned	Encode and decode CloudEvents in each event format.
Protocol binding modules (HTTP, Kafka, AMQP, ...)	Planned	Transport-specific binary and structured content modes.

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KMP Target Matrix

Target	Platform	CI Status
jvm	Any (JDK 21+)	Tested
js (Node)	Node.js >= 18	Tested
wasmJs (Node)	Node.js >= 18	Tested
linuxX64	Linux x86-64	Tested
linuxArm64	Linux ARM64	Planned CI
macosX64	macOS x86-64	Planned CI
macosArm64	macOS Apple Silicon	Planned CI
iosArm64	iOS device (ARM64)	Planned CI
iosX64	iOS Simulator (x86-64)	Planned CI
iosSimulatorArm64	iOS Simulator (Apple Silicon)	Planned CI
mingwX64	Windows x86-64	Planned CI

"Tested" targets run on ubuntu-latest in CI on every PR. "Planned CI" targets compile on any host but require a macOS (Apple targets) or Windows (mingwX64) runner for test execution; these are added in a future CI expansion.

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Installation

Note: cloudevents-kotlin-core is not yet published to Maven Central. Until a release is available, add it as a project dependency from source.

The artifact coordinates when published will be:

// build.gradle.kts
dependencies {
    // cloudevents-kotlin-core is not yet published; add as a project dependency for now
    implementation("io.cloudevents:cloudevents-kotlin-core:<version>")
}

Group: io.cloudevents Artifact: cloudevents-kotlin-core

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Contributing

Contributions are welcome. Before submitting a pull request, please read CONTRIBUTING.md for the full workflow — covering branching, DCO sign-off, Conventional Commits, build and test instructions, and the code review process.

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Links

• CONTRIBUTING.md — contribution workflow and guidelines
• CloudEvents specification — normative spec source
• CloudEvents SDK requirements — version-support policy and SDK conformance requirements
• CloudEvents website — overview and community resources

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License

Apache License 2.0 — see LICENSE.