ApsaraMQ for RocketMQ:Send and receive scheduled messages

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using ons;

namespace ons
{
    class onscsharp
    {
        private static readonly DateTime Jan1st1970 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

        public static long CurrentTimeMillis()
        {
           return (long) (DateTime.UtcNow - Jan1st1970).TotalMilliseconds;
        }

        static void Main(string[] args)
        {
            // Configure the producer.
            ONSFactoryProperty factoryInfo = new ONSFactoryProperty();
            // Consumer group ID created in the ApsaraMQ for RocketMQ console.
            factoryInfo.setFactoryProperty(ONSFactoryProperty.ProducerId, "<your-group-id>");
            // TCP endpoint from the Instance Details page.
            factoryInfo.setFactoryProperty(ONSFactoryProperty.NAMESRV_ADDR, "<your-tcp-endpoint>");
            // Topic created in the ApsaraMQ for RocketMQ console.
            factoryInfo.setFactoryProperty(ONSFactoryProperty.PublishTopics, "<your-topic>");
            // Message content.
            factoryInfo.setFactoryProperty(ONSFactoryProperty.MsgContent, "scheduled_msg_body");
            // Load AccessKey credentials from environment variables.
            // Make sure ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET are set.
            factoryInfo.setFactoryProperty(ONSFactoryProperty::AccessKey, getenv("ALIBABA_CLOUD_ACCESS_KEY_ID"));
            factoryInfo.setFactoryProperty(ONSFactoryProperty::SecretKey, getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET"));

            // Create and start the producer. Call start() only once before sending messages.
            Producer pProducer = ONSFactory.getInstance().createProducer(factoryInfo);
            pProducer.start();

            Message msg = new Message(
                factoryInfo.getPublishTopics(),  // Topic
                "TagA",                          // Message tag for filtering
                factoryInfo.getMessageContent()  // Message body
            );

            // Set a business key for message tracing in the console.
            // Optional -- messages send and receive correctly without a key.
            msg.setKey("ORDERID_100");

            // Set the delivery time to 3 seconds from now (millisecond Unix timestamp).
            long deliverTime = CurrentTimeMillis() + 3000;
            msg.setStartDeliverTime(deliverTime);

            // Send the message. A successful call returns a SendResultONS object.
            try
            {
                SendResultONS sendResult = pProducer.send(msg);
            }
            catch(ONSClientException e)
            {
                // Handle send failures (network issues, invalid parameters, etc.).
            }

            // Shut down the producer before exiting to avoid memory leaks.
            pProducer.shutdown();

        }
    }
}