A simple JSON RPC 2.0 client over websockets

Open connection

const websocketUrl = 'ws://mywebsocketurl:port';
const requestTimeoutMs = 2000;
const websocket = new JsonRpcWebsocket(websocketUrl, requestTimeoutMs, (error: JsonRpcError) => {
  /* handle error */
});
await websocket.open();

Requests that do not receive a response within the specified timeout will fail with a REQUEST_TIMEOUT code. The callback (optional) is used for eventual errors, such as receiving a response that does not match any request id and connection errors. Furthermore, all errors that are sent to an eventual caller are also reported on the callback, e.g. if an rpc method is called with an invalid number of parameters, etc...

Close connection

await websocket.close();

Call RPC method

Considering that the server has a method sum(a: int, b: int)

with positional parameters

websocket.call('sum', [1, 2])
  .then((response) => {
    // handle response
  })
  .catch((error) => {
    // handle error
  });

with named parameters

websocket.call('sum', { b: 1, a: 2 })
  .then((response) => {
    // handle response
  })
  .catch((error) => {
    // handle error
  });

Send notification

Considering that the server has a method log(message: string)

websocket.notify('log', ['a log message']);

Define RPC method

websocket.on('sum', (a: number, b: number) => {
  return a + b;
});

The defined RPC methods can also be called with both positional and named parameters.

Minification/Obfuscation

When using code minification/obfuscation the parameter names may change, which can cause calls using named parameters to fail. To mitigate this you can do one or a combination of the following:

• do not minify/obfuscate the code where on is used, so the function registration does not get modified
• use positional parameters
• register functions as following:

websocket.on('sum', (params: { a: number; b: number }) => {
  return params.a + params.b;
});

and then call the function using positional parameters using the object:

websocket.call('sum', [{ a: 1, b: 2 }])
  .then((response) => {
    // handle response
  })
  .catch((error) => {
    // handle error
  });

Remove RPC method

websocket.off('sum');