azure-servicebus-various-client-handling-strategies

Program.cs

using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Azure.ServiceBus;

namespace bussub
{
    class Program
    {
        private static ConcurrentStack<long> tokens = new ConcurrentStack<long>();

        private const string ServiceBusConnectionString = "<connstringhere>";
        private const string TopicName = "<topicname>";
        private const string SubscriptionName = "<subname>";
        private static ISubscriptionClient _subscriptionClient;

        static void Main(string[] args)
        {
            MainAsync().GetAwaiter().GetResult();
        }

        private static async Task MainAsync()
        {
            _subscriptionClient = new SubscriptionClient(ServiceBusConnectionString, TopicName, SubscriptionName);

            Console.WriteLine("=======================================================");
            Console.WriteLine("Press ENTER key to exit after sending all the messages.");
            Console.WriteLine("=======================================================");

            RegisterOnMessageHandlerAndReceiveMessages();

            Console.ReadKey();

            await _subscriptionClient.CloseAsync();
        }

        private static void RegisterOnMessageHandlerAndReceiveMessages()
        {
            var messageHandlerOptions = new MessageHandlerOptions(ExceptionReceivedHandler)
            {
                MaxConcurrentCalls = 1,
                AutoComplete = false
            };

            
            _subscriptionClient.RegisterMessageHandler(ProcessMessagesAsync, messageHandlerOptions);

        }

        private static async Task ProcessMessagesAsync(Message message, CancellationToken token)
        {
            if (tokens.Contains(message.SystemProperties.SequenceNumber))
            {
                Console.WriteLine($"Already handled {message.SystemProperties.SequenceNumber}; abandoning");
                await _subscriptionClient.AbandonAsync(message.SystemProperties.LockToken);
            }
            else
            {
                tokens.Push(message.SystemProperties.SequenceNumber);
                if (message.SystemProperties.SequenceNumber % 2 == 0)
                {
                    Console.WriteLine($"Received message: SequenceNumber:{message.SystemProperties.SequenceNumber} Body:{Encoding.UTF8.GetString(message.Body)}");
                    await _subscriptionClient.CompleteAsync(message.SystemProperties.LockToken);
                }
                else
                {
                    if (message.SystemProperties.SequenceNumber % 7 == 0)
                    {
                        Console.WriteLine($"Sending {message.SystemProperties.SequenceNumber} straight to DLQ");
                        await _subscriptionClient.DeadLetterAsync(message.SystemProperties.LockToken, "7 goes to heaven");
                    }
                    else if (message.SystemProperties.SequenceNumber % 3 == 0)
                    {
                        Console.WriteLine($"Ignoring {message.SystemProperties.SequenceNumber}");
                        //if you don't abandon the message, it won't be rebroadcast until after the lock time expiry (default 30 s)
                        await Task.CompletedTask;

                    }
                    else
                    {
                        Console.WriteLine($"Abandoning {message.SystemProperties.SequenceNumber}");
                        await _subscriptionClient.AbandonAsync(message.SystemProperties.LockToken);
                    }

                }
            }
        }

        private static Task ExceptionReceivedHandler(ExceptionReceivedEventArgs exceptionReceivedEventArgs)
        {
            Console.WriteLine($"Message handler encountered an exception {exceptionReceivedEventArgs.Exception}.");
            var context = exceptionReceivedEventArgs.ExceptionReceivedContext;
            Console.WriteLine("Exception context for troubleshooting:");
            Console.WriteLine($"- Endpoint: {context.Endpoint}");
            Console.WriteLine($"- Entity Path: {context.EntityPath}");
            Console.WriteLine($"- Executing Action: {context.Action}");
            return Task.CompletedTask;
        }

    }
}