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Async Call

async-call-rpc is a JSON RPC server and client written in TypeScript for any ECMAScript environment.

Links

CHANGELOG.md | Document of AsyncCall | Document of AsyncGeneratorCall | Playground

Chapters:

• Installation
• channel, how to communicate
• encoder, how to use complex data types
• Example
• Notifications and Batch requests
• Package entries
• Builtin channels (including WebSocket)
• Implemented JSON RPC internal methods
• Non-standard extension to JSON RPC specification

Features

• Zero dependencies!
• Running in any ES6 environment, no requirement on any Web or Node API
• Simple to define a RPC server and simple to use as a RPC client
• Full TypeScript support
• Use a custom encoder to communicate with complex data types
• Support async generator (Require both server and client supports 4 JSON RPC internal methods listed below and async generator exists in the environment)

Cautions

• This package is shipping ECMAScript 2018 syntax (async function).
• The async generator support leaks memory on the server. Use it with caution.
• NOT support ES5.
• NOT support JSON RPC 1.0

Installation

Install via npm

npm i async-call-rpc

yarn add async-call-rpc

pnpm i async-call-rpc

Install via jsr

This package is published as @works/json-rpc on the jsr. If you install it via jsr, you should import this package from "@works/json-rpc" instead of "async-call-rpc"

deno add @works/json-rpc

npx jsr add @works/json-rpc

yarn dlx jsr add @works/json-rpc

pnpm dlx jsr add @works/json-rpc

bunx jsr add @works/json-rpc

Import from browser

You can access https://www.jsdelivr.com/package/npm/async-call-rpc?path=out to get the latest URL and SRI.

Note: the utils/ entrypoint is not published on the jsr.

import { AsyncCall } from 'https://cdn.jsdelivr.net/npm/async-call-rpc@latest/out/base.mjs'

UMD

<script src="https://cdn.jsdelivr.net/npm/async-call-rpc@2.0.1/out/base.js"></script>
<script>
    const { AsyncCall } = globalThis.AsyncCall
</script>

Other JS environments

Load the out/base.mjs (ES Module) or out/base.js (UMD, CommonJS, or AMD) to your project.

channel

To communicate with the server/client, you need to implement one of the following interfaces:

• CallbackBasedChannel, generally used in the server. Example: WebSocket on Node.
• EventBasedChannel, generally used in the client. Example: WebSocket on Web

There are some built-in channels you can simplify the usage.

The following document will assume you have defined your channel.

encoder

This library does not have any opinionated data transmitting format. You need to implement one of the following interfaces:

• IsomorphicEncoder. Example: JSONEncoder
• IsomorphicEncoderFull

Example

Server example

// server.ts
export function add(x: number, y: number) {
    return x + y
}
export const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms))

// init.ts
import { AsyncCall } from 'async-call-rpc'
import * as server from './server.ts'
// create a server
AsyncCall(server, { channel })

Client example

import { AsyncCall } from 'async-call-rpc'
import type * as server from './server.ts'
const server = AsyncCall<typeof server>({}, { channel })
server.add(2, 40).then(console.log) // 42

Notifications and Batch requests

AsyncCall can send notifications.

Using notifications means results or remote errors are never sent back. Local errors will not be omitted, e.g. encoder errors or network errors.

import { AsyncCall, notify } from 'async-call-rpc'
const server = notify(AsyncCall<typeof server>({}, { channel }))
server.add(1, 2).then(console.log) // undefined

AsyncCall can send batch request too.

import { AsyncCall, batch } from 'async-call-rpc'
const [server, emit, drop] = batch(AsyncCall<typeof server>({}, { channel }))
const a = server.req1() // pending
const b = server.req2() // pending
const c = server.req3() // pending
emit() // to send all pending requests
// request a, b, c sent

const d = server.req1() // pending
drop() // to drop all pending requests (and reject corresponding Promises)
// d rejected

Package entries

This library has 2 entries. base and full. base is the default entry point. The full version includes the AsyncGeneratorCall but the base version doesn't.

Browser / Deno

Please check out https://www.jsdelivr.com/package/npm/async-call-rpc?path=out

Node:

// Full version
require('async-rpc-call/full') // or
import { } from 'async-rpc-call/full'

// Base version
require('async-rpc-call') // or
import { } from 'async-rpc-call'

Builtin channels

They're not part of the core library but are provided as utils to increase usability.

(Node) WebSocket

(Deno) WebSocket

(Web) WebSocket

(Web) BroadcastChannel

(Web) Worker

Main thread: new WorkerChannel(new Worker(...))

Worker: new WorkerChannel()

Implemented JSON RPC internal methods

These four methods are used to implement AsyncGeneratorCall support.

interface JSONRPC_Internal_Methods {
    // These 4 methods represent the Async Iterator protocol in ECMAScript
    //This method starts an async iterator, returns the id
    'rpc.async-iterator.start'(method: string, params: unknown[]): Promise<string>
    //This method executes the `next` method on the previous iterator started by `rpc.async-iterator.start`
    'rpc.async-iterator.next'(id: string, value: unknown): Promise<IteratorResult<unknown>>
    //This method executes the `return` method on the previous iterator started by `rpc.async-iterator.start`
    'rpc.async-iterator.return'(id: string, value: unknown): Promise<IteratorResult<unknown>>
    //This method executes the `throw` method on the previous iterator started by `rpc.async-iterator.start`
    'rpc.async-iterator.throw'(id: string, value: unknown): Promise<IteratorResult<unknown>>
}

Non-standard extension to JSON RPC specification

remoteStack on the Request object

This library can send the client the call stack to the server to make the logger better.

Controlled by option.log.sendLocalStack. Default to false.

interface JSONRPC_Request_object {
    // This property includes the caller's stack.
    remoteStack?: string
}

"undef" on Response object

This is a non-standard property that appears when using the deprecated JSONSerialization due to JSON doesn't support undefined. It's a hint to the client, that the result is undefined.

This behavior is controlled by the 3rd parameter of JSONSerialization(replacerAndReceiver?, space?, undefinedKeepingBehavior?: false | "keep" | "null" = "null"). Default to "null". To turn on this feature to "keep" undefined values, change the 3rd option to "keep".

interface JSONRPC_Response_object {
    // This property is a hint.
    // If the client is run in JavaScript, it should treat "result: null" as "result: undefined"
    undef?: boolean
}

The implementation-defined Error data

In the JSON RPC specification, this is implementation-defined. This is controlled by the option options.mapError

This library will try to "Recover" the Error object if there is enough information from another side.

interface JSONRPC_Error_object {
    // This property will help the client to build a better Error object.
    data?: {
        stack?: string
        // Supported value for "type" field (Defined in ECMAScript specification):
        type?:
            | string
            | 'Error'
            | 'EvalError'
            | 'RangeError'
            | 'ReferenceError'
            | 'SyntaxError'
            | 'TypeError'
            | 'URIError'
            // Defined in HTML specification, only supported in Web
            | 'DOMException'
    }
}