subscribe
Receive incoming messages by creating a new, dedicated socket connection. After making a subscribe request, incoming messages will be sent to the client encoded as ClientMessageWrapper. When finished, to prevent leaks, send an unsubscribe request via Subscription.unsubscribe or disconnect from the socket via PersistentSocketWrapper.close to stop receiving messages.
Throws
if signald sends an error response or the incoming message is invalid
if the request to the socket fails