Json RPC

Idiomatic Json RPC Implementation in Kotlin and kotlinx.serialization. It has ktor implementation, but more engines may be added if needed. It is really simple to implement, but annoying to do every time for every project, so I made this into library.

import me.y9san9.jsonrpc.JsonRpc
import me.y9san9.jsonrpc.ktor.ktor

suspend fun main() {
    val rpc = JsonRpc.websocket("wss://example.org")

    rpc.connect {
        val response = execute(...)

        incoming.onRequest { request ->
            println("Incoming Request: $request")
            respond(response)
        }

        incoming.onRequest(JsonRpcMethodName("test")) { /* ... */ }
    }
}

Library is available on Maven Central and may be installed in the following ways:

dependencies {
    implementation("io.github.mzd00.jsonrpc:ktor-client:$version")
}

[versions]
jsonrpc = "$version"

[libraries]
jsonrpc = { module = "io.github.mzd00.jsonrpc:ktor-client", version.ref = "jsonrpc" }

$version should be the same as the last version in releases section.

Requests have a finite 30-second deadline covering transport send and response receipt. A timeout throws JsonRpcRequestTimeoutException, permanently fails the connection, and is classified by the Ktor adapter as a transport failure even if the first timeout is caught inside the connection block. Use an explicit config to choose another positive finite duration:

val config = JsonRpcConfig(
    side = JsonRpcSide.Client,
    requestTimeout = 2.minutes,
)
val rpc = JsonRpc.websocket("wss://example.org", config)

This fork is an internal library. Binary compatibility is not guaranteed between releases; consumers must be recompiled when upgrading.

Maintainer instructions for signing and publishing releases are in docs/Publishing.md.

TODO: at the moment only client behaviour is supported. Since I myself don't have any jsonrpc server to build with this. What I want to add for server is different errors that Server will tell to Client if Client did mistaked.

And, of course, an intergration with ktor-server is still missing, but it's not hard to master. I also would want to introduce dsl for ktor-server that looks like this:

embeddedServer {
    jsonrpc { this: JsonRpcServer
        // launch a coroutine to respond to methods
        method("test") { call: JsonRpcCall ->
            call.respond(/* ... */)
            call.notification(/* ... */)
        }
        // this.jsonrpc works fine
    }
}