ApsaraMQ for RocketMQ:Send and receive scheduled and delayed messages over HTTP (C#)

using System;
using System.Collections.Generic;
using System.Threading;
using Aliyun.MQ.Model;
using Aliyun.MQ.Model.Exp;
using Aliyun.MQ.Util;

namespace Aliyun.MQ.Sample
{
    public class ProducerSample
    {
        // HTTP endpoint. Get this from the Instance Details page in the ApsaraMQ for RocketMQ console.
        private const string _endpoint = "<your-http-endpoint>";

        // Get AccessKey credentials from environment variables.
        // Do not hardcode credentials in your source code.
        private const string _accessKeyId = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID");
        private const string _secretAccessKey = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET");

        // Topic to publish to. Create this in the ApsaraMQ for RocketMQ console.
        private const string _topicName = "<your-topic>";

        // Instance ID. If the instance has no namespace, set this to null or "".
        // Check the Instance Details page to determine whether your instance has a namespace.
        private const string _instanceId = "<your-instance-id>";

        private static MQClient _client = new Aliyun.MQ.MQClient(_accessKeyId, _secretAccessKey, _endpoint);

        static MQProducer producer = _client.GetProducer(_instanceId, _topicName);

        static void Main(string[] args)
        {
            try
            {
                for (int i = 0; i < 4; i++)
                {
                    TopicMessage sendMsg;
                    sendMsg = new TopicMessage("hello mq");

                    // Set a custom property on the message.
                    sendMsg.PutProperty("a", i.ToString());

                    // Key line: set the delivery time.
                    // Delayed message: add the delay (in ms) to the current timestamp.
                    // Scheduled message: set the parameter to the time difference between the scheduled point in time and the current point in time.
                    sendMsg.StartDeliverTime = AliyunSDKUtils.GetNowTimeStamp() + 10 * 1000; // 10-second delay

                    TopicMessage result = producer.PublishMessage(sendMsg);
                    Console.WriteLine("Message published: " + result);
                }
            }
            catch (Exception ex)
            {
                Console.Write(ex);
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Threading;
using Aliyun.MQ.Model;
using Aliyun.MQ.Model.Exp;
using Aliyun.MQ;

namespace Aliyun.MQ.Sample
{
    public class ConsumerSample
    {
        // HTTP endpoint. Get this from the Instance Details page in the ApsaraMQ for RocketMQ console.
        private const string _endpoint = "<your-http-endpoint>";

        // The AccessKey ID that is used for authentication.
        private const string _accessKeyId = "${ACCESS_KEY}";
        // The AccessKey secret that is used for authentication.
        private const string _secretAccessKey = "${SECRET_KEY}";

        // Topic to consume from. Create this in the ApsaraMQ for RocketMQ console.
        private const string _topicName = "<your-topic>";

        // Instance ID. If the instance has no namespace, set this to null or "".
        private const string _instanceId = "<your-instance-id>";

        // Consumer group ID. Create this in the ApsaraMQ for RocketMQ console.
        private const string _groupId = "<your-group-id>";

        private static MQClient _client = new Aliyun.MQ.MQClient(_accessKeyId, _secretAccessKey, _endpoint);
        static MQConsumer consumer = _client.GetConsumer(_instanceId, _topicName, _groupId, null);

        static void Main(string[] args)
        {
            // Consume messages in a loop. For production use, run multiple threads concurrently.
            while (true)
            {
                try
                {
                    // Long polling: if no messages are available, the request waits on the broker
                    // for up to the specified number of seconds before returning.
                    List<Message> messages = null;

                    try
                    {
                        messages = consumer.ConsumeMessage(
                            3, // Max messages per batch (up to 16)
                            3  // Long polling timeout in seconds (up to 30)
                        );
                    }
                    catch (Exception exp1)
                    {
                        if (exp1 is MessageNotExistException)
                        {
                            Console.WriteLine(Thread.CurrentThread.Name + " No new message, " + ((MessageNotExistException)exp1).RequestId);
                            continue;
                        }
                        Console.WriteLine(exp1);
                        Thread.Sleep(2000);
                    }

                    if (messages == null)
                    {
                        continue;
                    }

                    List<string> handlers = new List<string>();
                    Console.WriteLine(Thread.CurrentThread.Name + " Receive Messages:");

                    // Process each message.
                    foreach (Message message in messages)
                    {
                        Console.WriteLine(message);
                        Console.WriteLine("Property a is:" + message.GetProperty("a"));
                        handlers.Add(message.ReceiptHandle);
                    }

                    // Acknowledge messages. If the broker does not receive an ACK
                    // before Message.nextConsumeTime, it redelivers the message.
                    // Each delivery assigns a new receipt handle.
                    try
                    {
                        consumer.AckMessage(handlers);
                        Console.WriteLine("Ack message success:");
                        foreach (string handle in handlers)
                        {
                            Console.Write("\t" + handle);
                        }
                        Console.WriteLine();
                    }
                    catch (Exception exp2)
                    {
                        // An ACK can fail if the receipt handle has expired.
                        if (exp2 is AckMessageException)
                        {
                            AckMessageException ackExp = (AckMessageException)exp2;
                            Console.WriteLine("Ack message fail, RequestId:" + ackExp.RequestId);
                            foreach (AckMessageErrorItem errorItem in ackExp.ErrorItems)
                            {
                                Console.WriteLine("\tErrorHandle:" + errorItem.ReceiptHandle + ",ErrorCode:" + errorItem.ErrorCode + ",ErrorMsg:" + errorItem.ErrorMessage);
                            }
                        }
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex);
                    Thread.Sleep(2000);
                }
            }
        }
    }
}