The WebSocket Application Messaging Protocol (WAMP) https://wamp-proto.org/ provides RPC (Remote Procedure Call) and PubSub (Publish & Subscribe) messaging patterns on top of raw WebSocket for that purpose.
WAMP is a proper WebSocket subprotocol, uses WebSocket as transport and JSON as a payload format. RPC is implemented using 3 messages, and those messages contain a “Call ID” to correlate asynchronous RPC server responses to client initiated procedure calls.
Disclaimer: I am author of WAMP and some (open-source) WAMP implementations. Its an open initiative, with others already started to get on the boat. Ultimately, there should be a WAMP RFC properly defining the protocol .. but its still in the early stages.