protected CommandFactory getCommandFactory(Connection conn) {
        ProtocolCode protocolCode = conn.getChannel().attr(Connection.PROTOCOL).get();
        return getCommandFactory(protocolCode);
    }
Create invoke future with {@link InvokeContext}.
@param conn
@param request
@param invokeContext
@param invokeCallback
@return
src/main/java/com/alipay/remoting/BaseRemoting.java