WebSocket

API Definition

api.ts

export type API = {
  add: (a: number, b: number, callback?: (sum: number) => void) => Promise<number>
}

export const apiMethods: API = {
  add: async (a, b, callback) => {
    callback?.(a + b)
    return a + b
  }
}

Server

server.ts

import { expose } from "kkrpc"
import { webSocketTransport } from "kkrpc/ws"
import { WebSocketServer } from "ws"
import { apiMethods } from "./api"

const wss = new WebSocketServer({ port: 3000 })

wss.on("connection", (ws) => {
  expose(apiMethods, webSocketTransport(ws))
})

Client

client.ts

import { wrap } from "kkrpc"
import { webSocketClientTransport } from "kkrpc/ws"
import type { API } from "./api"

const api = wrap<API>(webSocketClientTransport("ws://localhost:3000"))

const sum = await api.add(5, 3)
await api.add(10, 20, (value) => console.log(value))

Reconnecting

WebSocket connections can drop. Pass onClose to the channel to detect it — in-flight calls reject immediately with RPCTransportClosedError instead of hanging until their timeout — and rebuild the transport and channel to reconnect. See the connection lifecycle guide for the full contract.

client.ts

import { RPCChannel } from "kkrpc"
import { webSocketClientTransport } from "kkrpc/ws"
import type { API } from "./api"

function connect(): RPCChannel<object, API> {
  const channel = new RPCChannel<object, API>(webSocketClientTransport("ws://localhost:3000"), {
    onClose: (reason) => {
      console.warn("connection lost:", reason)
      channel.destroy()
      setTimeout(connect, 1000) // reconnect with backoff of your choosing
    }
  })
  return channel
}

const channel = connect()
const api = channel.getAPI()