json-rpc2-implementer

This is JSON-RPC 2.0 server and client JavaScript/TypeScript implementation. json-rpc2-implementer is only formatter, parser, and wrapper. It is not included any HTTP, TCP and WebSocket endpoints.

Install

To install json-rpc2-implementer in the current directory, run:

npm install json-rpc2-implementer

Usage

You must integrate json-rpc2-implementer to your application. But you can integrate every HTTP server, WebSocket server and other application.

import * as WebSocket from 'ws';
import { JsonRpc2Implementer } from 'json-rpc2-implementer';

const WebSocketServer = WebSocket.Server;
const wss = new WebSocketServer({ port: 3000 });
wss.on('connection', async function (ws: WebSocket) {
	const rpc = new JsonRpc2Implementer();
	rpc.sender = (message) => ws.send(message);
	rpc.methodHandler = (method: string, params: any) => {
		console.log(`CALLED method=${method},params=${params}`);
		return `Hello JSON-RPC2 method=${method},params=${params}`;
	};

	ws.on('message', (message) => rpc.receive(message));

	const result = await rpc.call('hello', { key: 1 });
	console.log(result);
});

When you use json-rpc2-implementer for wrapper, you must set sender and methodHandler properties and create function for call to receive().

API

Class: JsonRpc2Implementer

rpc.call(method[, params, id])

• method {String} The method name to call.
• params {Any} The parameters for the method. params will be conveted by JSON.stringify().
• id {Number|String} The id for JSON-RPC request. Defaults to serial number by generated in each instances.

Call to the remote procedure by sender and receive(). call() wait the response from the procedure and return Promise.<Any> included the result.

ATTENTION: call() check timeout at response. If the request timeouted, call() reject TimeoutError. But the receiver's status is uncertain.

rpc.notice(method[, params])

• method {String} The method name to call.
• params {Any} The parameters for the method. params will be conveted by JSON.stringify().

Notice to the remote procedure by sender. notice() return Promise.<void> but it doesn't wait the response.

rpc.receive(message)

• message {String} The received message.

Receive a JSON-RPC request/response and call to methodHandler and return response by sender. receive() return Promise.<void> for send a response from methodHandler.

receive() also support batch request/response.

ATTENTION: receive() don't check jsonrpc property in the request/response. It is lazy receiver.

rpc.createRequest(method[, params, id])

• method {String} The method name to call.
• params {Any} The parameters for the method. params will be conveted by JSON.stringify().
• id {Number|String} The id for JSON-RPC request. Defaults to serial number by generated each instances.

Create a JSON-RPC2 request object.

rpc.createResponse(id, result[, error])

• id {Number|String} The id that JSON-RPC request specified.
• result {Any} The result from a local procedure. result will be conveted by JSON.stringify().
• error {Any} The error from a local procedure when an error occurs. error will be converted by JsonRpcError.convert().

Create a JSON-RPC2 response object.

rpc.createNotification(method[, params])

• method {String} The method name to call.
• params {Any} The parameters for the method. params will be conveted by JSON.stringify().

Create a JSON-RPC2 notification request object.

rpc.parse(message)

• message {String} The received message.

Parse a JSON-RPC request/response.

rpc.sender

• {Function}

The message sender for a JSON-RPC request/response from call(), notice() and receive(). The first argument of the sender must be string and send it to the server.

rpc.methodHandler

• {Function}

The method handler would be call from receive() when a JSON-RPC request received. The first argument of the handler must be any parameters for a JSON-RPC request's params. And also the second argument can be a ID for the request's id.

The result of the handler would be used to the response's result. If the handler throw error, receive() send an error response.

The handler can return the paramters that both generally value and Promise.

rpc.timeout

• {Number}

The timeout specify timeout wait msec for call(). Defaults to 60000 ms.

Class: JsonRpcError

new JsonRpcError([code, message, data])

• code {Number} The error code for a response. Defaults to ErrorCode.InternalError.
• message {String} The error message for a response. Defaults to the assigned message each error code constants or "Unknown Error".
• data {Any} The option data for a response.

Create a new error instance.

error.toJSON()

Create a new error object for a JSON-RPC2 response.

JsonRpcError.convert(error)

• error {Any} The error instance for a response.

Create a new JsonRpcError error instance from other Error.

ErrorCode constants

Constant	Value	Description
ParseError	-32700	The message can't be parsed.
InvalidRequest	-32600	The message is not JSON-RPC2 format.
MethodNotFound	-32601	The specified method is not found.
InvalidParams	-32602	The request parameter is invalid.
InternalError	-32603	Internal error.

There are only few error codes that JSON-RPC2 specified here. You can use other error code for your application.

Symbol: NoResponse

You can skip automatic response and send it manually in methodHandler.

Example

You can find a example web application here.

• ktanakaj/ws-chat-sample

License

MIT