jsonrpc-ws-provider

JSON-RPC WebSocket Provider to get results synchronously.

Most of the code is taken from web3.js, and I modified the Ethereum-specific implementation to make it universally usable with JSON-RPC.

Installation

https://www.npmjs.com/package/jsonrpc-ws-provider

$ npm i jsonrpc-ws-provider

Examples

const evmWsProvider = new JsonRpcWebSocketProvider('wss://{evm}');
const res1 = await evmWsProvider.request({
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_chainId',
    params: [],
});

const cosmosWsProvider = new JsonRpcWebSocketProvider('wss://{cosmos-sdk}/websocket');
const res2 = await cosmosWsProvider.request({
    jsonrpc: '2.0',
    id: 1,
    method: 'net_info',
    params: [],
});

Subscribe example

const NewBlockHeaderSubId = 'new_block_header_id';

const cosmosWsProvider = new JsonRpcWebSocketProvider('wss://{cosmos-sdk}/websocket');
cosmosWsProvider.request({
    method: 'subscribe',
    params: ["tm.event = 'NewBlockHeader'"],
    jsonrpc: '2.0',
    id: NewBlockHeaderSubId,
});

cosmosWsProvider.on(
    'message',
    async (jsonrpcRes: JsonRpcResponseWithResult<any>) => {
        if (Object.keys(jsonrpcRes?.result).length !== 0) {
            if (jsonrpcRes?.id === NewBlockHeaderSubId) {
                const newBlockHeader = jsonrpcRes?.result?.data;
                if (newBlockHeader?.type !== 'tendermint/event/NewBlockHeader') {
                    throw new Error('Invalid event type');
                }
                const height = newBlockHeader?.value?.header?.height;

                console.log(`new block detected ${height}`);
            }
        }
    }
);

disconnectionCheckInterval

The default logic is to try to connect when the request method is called if the connection is lost. This can cause unintended behavior if you have set up logic for when you receive a reconnection event. For example, let's say you're making a subscribe request to an endpoint and periodically polling it for values. For reliability, you implemented the onReconnect method to make a subscribe request when the connection is disconnected and reconnected. With the existing logic, this means that the onReconnect method will not be executed until you call request, and you could lose data in the meantime! In this case, setting the disconnectionCheckInterval value will cause the onReconnect method to be executed after the set interval instead of waiting for the request to be called.

(onReconnect example)

async function onReconnect(provider: JsonRpcWebSocketProvider): Promise<void> {
    // Recover logic
    // ...

    subscribeNewBlockHeader(provider);
}

async function subscribeNewBlockHeader(provider: JsonRpcWebSocketProvider): Promise<void> {
    provider.request({
        method: 'subscribe',
        params: ["tm.event = 'NewBlockHeader'"],
        jsonrpc: '2.0',
        id: NewBlockHeaderSubId,
    });

    provider.once('connect', onReconnect);
}

async function detectNewBlockHeader(provider: JsonRpcWebSocketProvider): Promise<void> {
    subscribeNewBlockHeader(provider);

    provider.on(
        'message',
        async (response: any) => {
            // Handle response
            // ...
        },
    );
}