Process a raw wire payload (single message or batch) and return the raw
response text, or empty string when there is nothing to send back (e.g.
a notification, or an all-notification batch). Parse/envelope failures
become JSON-RPC error responses with a null id.
Process a raw wire payload (single message or batch) and return the raw response text, or empty string when there is nothing to send back (e.g. a notification, or an all-notification batch). Parse/envelope failures become JSON-RPC error responses with a null id.