Features

Edit pageLast modified: 04 April 2025

Send and receive Flows

You can send and receive Kotlin Flows in RPC methods. However, this only applies to the Flow type. StateFlow and SharedFlow are not supported, and there are no plans to add support for them.

@Serializable
data class StreamRequest(
    @Contextual
    val innerFlow: Flow<Int>
)

@Rpc
interface MyService : RemoteService {
    fun sendStream(stream: Flow<Int>): Flow<String>

    suspend fun streamRequest(request: StreamRequest)
}

Another requirement is that server-side steaming (flows that are returned from a function), must be the top-level type and the function must be non-suspending:

@Serializable
data class StreamResult(
    @Contextual
    val innerFlow: Flow<Int>
)

@Rpc
interface MyService : RemoteService {
    fun serverStream(): Flow<String> // ok
    suspend fun serverStream(): Flow<String> // not ok
    suspend fun serverStream(): StreamResult // not ok
}

note

Note that flows that are declared in classes (like in StreamResult) require a Contextual annotation.