@Override
    public boolean allocServiceAddress(RoutingNode recipient) {
        Hop hop = recipient.getRoute().getHop(0);
        String service = hop.getServiceName();
        Error error = resolveServiceAddress(recipient, service);
        if (error == null) {
            return true; // service address resolved
        }
        recipient.setError(error);
        return false; // service address not resolved
    }
The network uses a cache of RPC targets (see {@link RPCTargetPool}) that allows it to save time by reusing open
connections. It works by keeping a set of the most recently used targets open. Calling this method forces all
unused connections to close immediately.
messagebus/src/main/java/com/yahoo/messagebus/network/rpc/RPCNetwork.java