連絡
R·E·N·R·A·K·U

"an api should just be a bunch of async functions, damn it!"
    — Chase Moskal, many years ago

renraku is a magic typescript json-rpc library that makes life joyous again.

📦 npm install @e280/renraku
💡 async functions as api
🔌 http, websockets, postmessage, anything
↔️ fully stoked for bidirectionality
🌐 node + browser
🏛️ json-rpc 2.0
🤖 for web workers, see comrade
💻 an https://e280.org/ project

⛩️ RENRAKU http api

1. 🍏 your api is just async functions — rpc.ts

   import Renraku from "@e280/renraku"
   
   export type MyFns = Awaited<ReturnType<typeof myRpc>>
   
   export const myRpc = Renraku.asRpc(async meta => ({
     async now() {
       return Date.now()
     },
   
     async add(a: number, b: number) {
       return a + b
     },
   
     nesty: {
       is: {
         besty: {
           async mul(a: number, b: number) {
             return a * b
           },
         },
       },
     },
   }))

   • meta.request is the http node request object (with headers and stuff)
   • meta.ip is the ip address associated with the request
   • for input validation, you should use zod or something
2. 🍏 make an http server — server.ts

   import Renraku from "@e280/renraku"
   import {myRpc} from "./rpc.js"
   
   await new Renraku.Server({rpc: myRpc})
     .listen(8000)

   • your functions are served on a POST / json-rpc 2.0 endpoint
   • you get a free GET /health route that returns the current js timestamp
3. 🍏 make a clientside remote — client.ts

   import Renraku from "@e280/renraku"
   import type {MyFns} from "./rpc.js"
   
   const remote = Renraku.httpRemote<MyFns>({url: "http://localhost:8000/"})

   🪄 now you can magically call the functions on the clientside

   await remote.now()
     // 1753780093703
   
   await remote.add(2, 2)
     // 4
   
   await remote.nesty.is.besty.mul(2, 3)
     // 6

👹 roll your own: node http integration

if you're feeling spartan, you can produce an ordinary node http RequestListener for your rpc functions:

import Renraku from "@e280/renraku"
import * as http from "node:http"
import {myRpc} from "./rpc.js"

const requestListener = Renraku.makeRequestListener({rpc: myRpc})

new http.Server(requestListener)
  .listen(8000)

⛩️ RENRAKU websockets api

renraku websocket apis are bidirectional, meaning the serverside and clientside can call each other.. just be careful not to create a circular loop, lol..

and yes — a single renraku server can support an http rpc endpoint and a websocket api simultaneously.

1. 🍏 make your serverside — serverside.ts

   import Renraku from "@e280/renraku"
   import type {Clientside} from "./clientside.js"
   
   export type Serverside = {
     now(): Promise<number>
   }
   
   export const serverside = (
     Renraku.asAccepter<Serverside, Clientside>(async connection => {
       console.log("connected", connection.ip)
       return {
         fns: {
           async now() {
             // 🫨 omg we're calling the clientside from the serverside!
             await connection.remote.sum(1, 2)
             return Date.now()
           },
         },
         disconnected() {
           console.log("disconnected", connection.ip)
         },
       }
     })
   )

2. 🍏 make your clientside — clientside.ts

   import Renraku from "@e280/renraku"
   import type {Serverside} from "./serverside.js"
   
   export type Clientside = {
     sum(a: number, b: number): Promise<number>
   }
   
   export const clientside = (
     Renraku.asConnector<Clientside, Serverside>(async connection => {
       console.log("connected")
       return {
         fns: {
           async sum(a: number, b: number) {
             return a + b
           },
         },
         disconnected() {
           console.log("disconnected")
         },
       }
     })
   )

3. 🍏 run the websocket server — server.ts

   import Renraku from "@e280/renraku"
   import {serverside} from "./serverside.js"
   
   await new Renraku.Server({websocket: serverside})
     .listen(8000)

4. 🍏 connect as a client — client.ts

   import Renraku from "@e280/renraku"
   import {clientside} from "./clientside.js"
   
   const connection = await Renraku.wsConnect({
     connector: clientside,
     socket: new WebSocket("ws://localhost:8000/"),
   })
   
   // call the serverside functionality
   const result = await connection.remote.now()
     // 1753738662615
   
   // get the average ping time in milliseconds
   connection.rtt.average
     // 99
   
   // kill the connection
   connection.close()

5. 🍏 the connection object has a bunch of good stuff
   • all connection objects have this stuff:

     connection.socket // raw websocket instance
     
     connection.rtt.latest // latest known ping time in milliseconds
     connection.rtt.average // average of a handful of latest ping results
     connection.rtt.on(rtt => {}) // subscribe to individual ping results
     
     // remote for calling fns on the other side
     await connection.remote.sum(1, 2)
     
     // kill this connection
     connection.close()

   • serverside connections also have HttpMeta stuff:

     connection.ip // ip address of the client
     connection.request // http request with headers and such

👹 roll your own: websocket upgrader integration

WsIntegration provides an upgrader that you can plug into a stock node http server:

import Renraku from "@e280/renraku"
import * as http from "node:http"
import {serverside} from "./serverside.js"

const server = new http.Server()
const websockets = new Renraku.WsIntegration({accepter: serverside})
server.on("upgrade", websockets.upgrader)

⛩️ RENRAKU gnarly details

🍏 all Renraku.Server options

new Renraku.Server({

  // expose http json-rpc api
  rpc: async meta => ({
    async hello() { return "lol" },
  }),

  // expose websocket json-rpc api
  websocket: Renraku.asAccepter<Serverside, Clientside>(
    async connection => ({
      fns: {async hello() { return "lmao" }},
      disconnected() {},
    })
  ),

  // supply a logger to get verbose console output (only logs errors by default)
  tap: new Renraku.LoggerTap(),

  // allow cross-origin requests (cors is disabled by default)
  cors: {origins: "*"},
  
  // request timeout in milliseconds (defaults to 60_000)
  timeout: 60_000,

  // requests with bodies bigger than this number are rejected (10 MB default)
  maxRequestBytes: 10_000_000,

  // specify the url of the rpc endpoint (defaults to `/`)
  rpcRoute: "/",

  // specify the url of the health endpoint (defaults to `/health`)
  healthRoute: "/health",

  // provide a transmuter that modifies incoming requests before routing
  transmuters: [],

  // you can provide custom listeners for additional http routes..
  routes: [
    Renraku.route.get("/hello", Renraku.respond.text("hello world")),
  ],
})

🍏 logging and error handling

• renraku has this concept of a Tap, which allows you to hook into renraku for logging purposes
• almost every renraku facility, can accept a tap — like makeRemote, makeEndpoint, etc
  • ErrorTap (default) — logs errors, but not every request
  • LoggerTap — (default for Server) verbose logging, all errors and every request
  • DudTap — silent, doesn't log anything

🍏 error handling

• for security-by-default, when renraku encounters an error, it reports unexposed error to the client

  const timingApi = {
    async now() {
      throw new Error("not enough minerals")
        //                   ☝️
        // secret message is hidden from remote clients
    },
  }

• but you can throw an ExposedError when you want the error message sent to the client

  import {ExposedError} from "@e280/renraku"
  
  const timingApi = {
    async now() {
      throw new ExposedError("insufficient vespene gas")
        //                        ☝️
        //             publicly visible message
    },
  }

• any other kind of error will NOT send the message to the client
• the intention here is security-by-default, because error messages could potentially include sensitive information

🍏 secure and authorize auth helpers

• use the secure function to section off parts of your api that require auth

  // auth param can be any type you want
  const secured = Renraku.secure(async(auth: string) => {
  
    // here you can do any auth work you need
    if (auth !== "hello")
      throw new Error("auth error: did not receive warm greeting")
  
    return {
      async sum(a: number, b: number) {
        return a + b
      },
    }
  })
  
  // 'secure' augments the functions to require the 'auth' param first
  await secured.sum("hello", 1, 2)

• use the authorize function on the clientside to provide the auth param upfront

  const authorized = Renraku.authorize(secured, async() => "hello")
  
  // now the auth is magically provided for each call
  await authorized.sum(1, 2)

  • but why an async getter function?
    because it's a perfect opportunity for you to refresh tokens or what-have-you.
    the getter is called for each api call.
• secure and authorize do not support arbitrary nesting, so you have to pass them a flat object of async functions

🍏 optimize fn calls

tune symbol

• all the functions on a renraku Remote can be 'tuned'
• import the symbol

  import {tune} from "@e280/renraku"

• imagine we have some renraku remote

  await remote.sum(1, 2)
    // 3

• tune a call with notify

  await remote.sum[tune]({notify: true})(1, 2)
    // undefined

  • this is how we do a json-rpc protocol 'notification' request, which skips the response (for fire-and-forget actions)
  • sometimes responses are not needed, so this can be a nice little optimization
• tune a call with transfer

  const buffer = new Uint8Array([0xDE, 0xAD, 0xBE, 0xEF]).buffer
  
  await remote.deliver[tune]({transfer: [buffer]})(buffer)

  • this is how we specify transferables for fast zero-copy transfers between worker threads and such
  • important in sister project comrade for threading workloads

settings symbol

• it's a set-and-forget way to pre-configure the default behavior for a remote fn
• import the symbol

  import {settings} from "@e280/renraku"

• settings to configure notify permanently on a fn

  await remote.sum[settings].notify = true

  now future calls will use notify: true (unless tune overrides)

  await remote.sum(1, 2)
    // undefined

⛩️ RENRAKU messenger and conduits

Messenger is a bidirectional-capable api mediator, though it can also be used in a one-way capacity.

Conduit subclasses facilitate communications over various mediums:

• BroadcastConduit — for broadcast channel
• PostableConduit — for post message channels like web workers
• WindowConduit — for window post message channels
• WebsocketConduit — used under the hood for websockets (but you should use wsConnect helper instead)

the following examples will demonstrate using Messengers with WindowConduits for a common popup api example.

🍏 incredible high-effort diagram

+----ALPHA----+      +----BRAVO----+
|             |      |             |
|  [Conduit]<==========>[Conduit]  |
|      |      |      |      |      |
| [Messenger] |      | [Messenger] |
|             |      |             |
+-------------+      +-------------+

• "alpha and bravo" could be a "clientside and serverside" or "window and popup" or whatever
• the point is, each side gets its own conduit and its own messenger
• the conduits are literally talking to each other
• the messenger's job is to deal with json-rpc and provide you with a callable remote and execute your local rpc endpoint

🍏 example — calling fns on a popup — one-way messenger

• api.ts — make a popup api

  import Renraku from "@e280/renraku"
  
  export const appOrigin = "https://example.e280.org"
  export type PopupFns = Awaited<ReturnType<typeof popupRpc>>
  
  export const popupRpc = Renraku.asMessengerRpc(async meta => ({
    async sum(a: number, b: number) {
      return a + b
    },
  }))

• popup.ts — in the popup, we create a messenger to expose our fns

  import Renraku from "@e280/renraku"
  import {popupRpc, appOrigin} from "./api.js"
  
  const messenger = new Renraku.Messenger({
    rpc: popupRpc,
    conduit: new Renraku.conduits.WindowConduit({
      localWindow: window,
      targetWindow: window.opener,
      targetOrigin: appOrigin,
      allow: e => e.origin === appOrigin,
    }),
  })

• parent.ts — in the parent window, we create a messenger to call our fns

  import Renraku from "@e280/renraku"
  import {PopupFns, appOrigin} from "./api.js"
  
  const popup = window.open(`${appOrigin}/popup`)
  
  const messenger = new Renraku.Messenger<PopupFns>({
    conduit: new Renraku.conduits.WindowConduit({
      localWindow: window,
      targetWindow: popup,
      targetOrigin: appOrigin,
      allow: e => e.origin === appOrigin,
    }),
  })

  now we can call the popup's fns:

  await messenger.remote.sum(2, 3)
    // 5

🍏 example — bidirectional parent and popup calls — two-way messenger

• api.ts — make both apis

  import Renraku from "@e280/renraku"
  
  export const appOrigin = "https://example.e280.org"
  export type PopupFns = {sum(a: number, b: number): Promise<number>}
  export type ParentFns = {mul(a: number, b: number): Promise<number>}
  
  export const popupRpc = Renraku.asMessengerRpc<PopupFns, ParentFns>(async meta => ({
    async sum(a, b) {
      await meta.remote.mul(2, 3) // 🧐 yes, we can call the other side
      return a + b
    },
  }))
  
  export const parentRpc = Renraku.asMessengerRpc<ParentFns, PopupFns>(async meta => ({
    async mul(a, b) {
      return a * b
    },
  }))

• popup.ts — popup window side

  import Renraku from "@e280/renraku"
  import {appOrigin, popupRpc} from "./api.js"
  
  const messenger = new Renraku.Messenger({
    rpc: popupRpc,
    conduit: new Renraku.conduits.WindowConduit({
      localWindow: window,
      targetWindow: window.opener,
      targetOrigin: appOrigin,
      allow: e => e.origin === appOrigin,
    }),
  })

  now the popup can call parent fns

  await messenger.remote.mul(2, 3)
    // 6

• parent.ts — parent window side

  import Renraku from "@e280/renraku"
  import {appOrigin, parentRpc} from "./api.js"
  
  const popup = window.open(`${appOrigin}/popup`)
  
  const messenger = new Renraku.Messenger({
    rpc: parentRpc,
    conduit: new Renraku.conduits.WindowConduit({
      localWindow: window,
      targetWindow: popup,
      targetOrigin: appOrigin,
      allow: e => e.origin === appOrigin,
    }),
  })

  now the parent can call popup fns

  await messenger.remote.sum(2, 3)
    // 5

🍏 messenger zero-copy transferables

Messenger is often used across postMessage boundaries, to talk to popups, iframes, or web workers.

as such, you can set meta.transfer array, so you can return transferables:

export const popupRpc = Renraku.asMessengerRpc(async meta => ({
  async getData() {
    const bytes = new Uint8Array([0xB0, 0x0B, 0x1E, 0x5]).buffer
    meta.transfer = [bytes]
    return bytes // ⚡ transferred speedy-fastly
  },
}))

⛩️ RENRAKU core primitives

• TODO lol we should write more in depth docs about the core tools here
• makeEndpoint(~) — make a json-rpc endpoint fn for a group of async fns
• makeRemote(~) — make a nested proxy tree of invokable fns, given an endpoint
• makeMock(~) — sugar for making an endpoint and then a remote for the given fns
• JsonRpc — namespace of json rpc types and helpers
• fns(~) — typescript identity helper for a group of async fns
• types.ts — typescript identity helper for a group of async fns
  • AsFns<X> — ensures X is a group of valid async functions
  • Remote<MyFns> — adds the magic tune stuff to the provided MyFns types

⛩️ RENRAKU means contact

💖 free and open source just for you
🌟 reward us with github stars
💻 join us at e280 if you're a real one