Facilitates asynchronous Remote Procedure Call (RPC) services with simplified integrations, supporting flow-based data streaming. Offers transport-agnostic design, seamless integration with existing solutions, and customizable serialization protocols.
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[!NOTE] gRPC Kotlin Multiplatform support is now available for preview!
Try the new gRPC KMP integration and share your feedback. See gRPC Integration for details or check the documentation.
kotlinx.rpc is a Kotlin library for adding asynchronous Remote Procedure Call (RPC) services to your applications.
Build your RPC with already known language constructs and nothing more!
First, create your RPC service and define some methods:
@Rpc
interface AwesomeService {
fun getNews(city: String): Flow<String>
suspend fun daysUntilStableRelease(): Int
}
In your server code define how to respond by simply implementing the service:
( parameters: AwesomeParameters) : AwesomeService {
: Flow<String> {
flow {
emit()
emit()
emit()
}
}
: {
(parameters.stable) {
parameters.daysUntilStable ?: error()
}
}
}
Then, choose how do you want your service to communicate. For example, you can use integration with Ktor:
data class AwesomeParameters(val stable: Boolean, val daysUntilStable: Int?)
fun main() {
embeddedServer(Netty, 8080) {
install(Krpc)
routing {
rpc("/awesome") {
rpcConfig {
serialization {
json()
}
}
registerService<AwesomeService> {
AwesomeServiceImpl(AwesomeParameters(, ))
}
}
}
}.start(wait = )
}
To connect to the server use the following Ktor Client setup:
val rpcClient = HttpClient { installKrpc() }.rpc {
url("ws://localhost:8080/awesome")
rpcConfig {
serialization {
json()
}
}
}
val service = rpcClient.withService<AwesomeService>()
service.daysUntilStableRelease()
service.getNews("KotlinBurg").collect { article ->
println(article)
}
Check out our getting started guide for a thorough overview of all components and features.
To ensure that all IDE features of our compiler plugin work properly on IntelliJ-based IDEs, install the Kotlin External FIR Support plugin.
We support all stable Kotlin versions starting from 2.2.0:
For a full compatibility checklist, see Versions.
kotlinx.rpc is a KMP library, so we aim to support all available platforms.
However, we are also a multi-module library, meaning that some modules may not support some platforms.
Current high-level status:
For more detailed module by module information, check out our platform support table.
For information about gRPC, see gRPC Integration
kotlinx.rpc provides Gradle plugin org.jetbrains.kotlinx.rpc.plugin
that will set up code generation in a project.
Example of a setup in a project's build.gradle.kts:
plugins {
kotlin("multiplatform") version "2.4.0"
kotlin("plugin.serialization") version "2.4.0"
id("org.jetbrains.kotlinx.rpc.plugin") version "0.10.3"
}
To use kotlinx.rpc runtime dependencies, add Maven Central to the list of your repositories:
repositories {
mavenCentral()
}
And now you can add dependencies to your project:
dependencies {
// Client API
implementation("org.jetbrains.kotlinx:kotlinx-rpc-krpc-client:0.10.3")
// Server API
implementation("org.jetbrains.kotlinx:kotlinx-rpc-krpc-server:0.10.3")
// Serialization module. Also, protobuf and cbor are provided
implementation("org.jetbrains.kotlinx:kotlinx-rpc-krpc-serialization-json:0.10.3")
// Transport implementation for Ktor
implementation("org.jetbrains.kotlinx:kotlinx-rpc-krpc-ktor-client:0.10.3")
implementation()
implementation()
implementation()
}
You can see example projects in the samples folder.
kotlinx.rpc is designed to be transport agnostic.
That means that the library aims to provide the best RPC experience regardless of how the resulting messages are transferred.
That allows for easy integration into existing solutions, such as Ktor, without the need to rewrite code.
Add kotlinx.rpc, provide it with means to transfer encoded data (or use out-of-the-box integrations) and it will run.
With enough time it might even work with avian carriers.
kotlinx.rpc provides its own transfer protocol called kRPC, which takes responsibility for tracking serializing and handling other complex request operations.
When using kRPC you only need to provide a transport or choose from the officially supported ones:
Besides that, one can even provide their own protocol or integration with one to use with services and kotlinx.rpc API with it.
Though possible, it is much more complicated way to use the library and generally not needed.
kotlinx.rpc aims to provide support for the most common protocol integrations, as well as the in-house protocol called kRPC.
The library provides experimental support for the gRPC protocol. The artifacts are published separately in our Space repository. Current latest version:
Try it now — generate a gRPC + Ktor project with the Ktor Project Generator.
For more information on gRPC usage, see the official documentation. For a working example, see the sample gRPC JVM project and the sample gRPC KMP Project.
kotlinx.rpc is an official JetBrains product and is primarily developed by the team at JetBrains, with
contributions from the community.
Community support is available on the Kotlin Slack kotlinx-rpc channel
If you find a security vulnerability in kotlinx.rpc, we kindly request that you reach out to the JetBrains security team via
our responsible disclosure process.
Please see the contribution guide and the Code of conduct before contributing.
| Subsystem | Supported Platforms | Notes |
|---|
| Core | Jvm, Js, WasmJs, WasmWasi, Apple, Linux, Windows | |
| kRPC | Jvm, Js, WasmJs, Apple, Linux, Windows | WasmWasi is blocked by kotlin-logging |
| gRPC | Jvm | Projects with kotlin("jvm") only! KMP support is in development |