Amazon SNS examples using AWS SDK for .NET

The following code examples show you how to perform actions and implement common scenarios by using the AWS SDK for .NET with Amazon SNS.

Actions are code excerpts from larger programs and must be run in context. While actions show you how to call individual service functions, you can see actions in context in their related scenarios.

Scenarios are code examples that show you how to accomplish specific tasks by calling multiple functions within a service or combined with other AWS services.

Each example includes a link to the complete source code, where you can find instructions on how to set up and run the code in context.

Get started

The following code examples show how to get started using Amazon SNS.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



using Amazon.SimpleNotificationService;
using Amazon.SimpleNotificationService.Model;

namespace SNSActions;

public static class HelloSNS
{
    static async Task Main(string[] args)
    {
        var snsClient = new AmazonSimpleNotificationServiceClient();

        Console.WriteLine($"Hello Amazon SNS! Following are some of your topics:");
        Console.WriteLine();

        // You can use await and any of the async methods to get a response.
        // Let's get a list of topics.
        var response = await snsClient.ListTopicsAsync(
            new ListTopicsRequest());

        foreach (var topic in response.Topics)
        {
            Console.WriteLine($"\tTopic ARN: {topic.TopicArn}");
            Console.WriteLine();
        }
    }
}

For API details, see ListTopics in AWS SDK for .NET API Reference.

Actions

The following code example shows how to use CheckIfPhoneNumberIsOptedOut.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.


    using System;
    using System.Threading.Tasks;
    using Amazon.SimpleNotificationService;
    using Amazon.SimpleNotificationService.Model;

    /// <summary>
    /// This example shows how to use the Amazon Simple Notification Service
    /// (Amazon SNS) to check whether a phone number has been opted out.
    /// </summary>
    public class IsPhoneNumOptedOut
    {
        public static async Task Main()
        {
            string phoneNumber = "+15551112222";

            IAmazonSimpleNotificationService client = new AmazonSimpleNotificationServiceClient();

            await CheckIfOptedOutAsync(client, phoneNumber);
        }

        /// <summary>
        /// Checks to see if the supplied phone number has been opted out.
        /// </summary>
        /// <param name="client">The initialized Amazon SNS Client object used
        /// to check if the phone number has been opted out.</param>
        /// <param name="phoneNumber">A string representing the phone number
        /// to check.</param>
        public static async Task CheckIfOptedOutAsync(IAmazonSimpleNotificationService client, string phoneNumber)
        {
            var request = new CheckIfPhoneNumberIsOptedOutRequest
            {
                PhoneNumber = phoneNumber,
            };

            try
            {
                var response = await client.CheckIfPhoneNumberIsOptedOutAsync(request);

                if (response.HttpStatusCode == System.Net.HttpStatusCode.OK)
                {
                    string optOutStatus = response.IsOptedOut ? "opted out" : "not opted out.";
                    Console.WriteLine($"The phone number: {phoneNumber} is {optOutStatus}");
                }
            }
            catch (AuthorizationErrorException ex)
            {
                Console.WriteLine($"{ex.Message}");
            }
        }
    }

For API details, see CheckIfPhoneNumberIsOptedOut in AWS SDK for .NET API Reference.

The following code example shows how to use CreateTopic.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Create a topic with a specific name.


    using System;
    using System.Threading.Tasks;
    using Amazon.SimpleNotificationService;
    using Amazon.SimpleNotificationService.Model;

    /// <summary>
    /// This example shows how to use Amazon Simple Notification Service
    /// (Amazon SNS) to add a new Amazon SNS topic.
    /// </summary>
    public class CreateSNSTopic
    {
        public static async Task Main()
        {
            string topicName = "ExampleSNSTopic";

            IAmazonSimpleNotificationService client = new AmazonSimpleNotificationServiceClient();

            var topicArn = await CreateSNSTopicAsync(client, topicName);
            Console.WriteLine($"New topic ARN: {topicArn}");
        }

        /// <summary>
        /// Creates a new SNS topic using the supplied topic name.
        /// </summary>
        /// <param name="client">The initialized SNS client object used to
        /// create the new topic.</param>
        /// <param name="topicName">A string representing the topic name.</param>
        /// <returns>The Amazon Resource Name (ARN) of the created topic.</returns>
        public static async Task<string> CreateSNSTopicAsync(IAmazonSimpleNotificationService client, string topicName)
        {
            var request = new CreateTopicRequest
            {
                Name = topicName,
            };

            var response = await client.CreateTopicAsync(request);

            return response.TopicArn;
        }
    }

Create a new topic with a name and specific FIFO and de-duplication attributes.


    /// <summary>
    /// Create a new topic with a name and specific FIFO and de-duplication attributes.
    /// </summary>
    /// <param name="topicName">The name for the topic.</param>
    /// <param name="useFifoTopic">True to use a FIFO topic.</param>
    /// <param name="useContentBasedDeduplication">True to use content-based de-duplication.</param>
    /// <returns>The ARN of the new topic.</returns>
    public async Task<string> CreateTopicWithName(string topicName, bool useFifoTopic, bool useContentBasedDeduplication)
    {
        var createTopicRequest = new CreateTopicRequest()
        {
            Name = topicName,
        };

        if (useFifoTopic)
        {
            // Update the name if it is not correct for a FIFO topic.
            if (!topicName.EndsWith(".fifo"))
            {
                createTopicRequest.Name = topicName + ".fifo";
            }

            // Add the attributes from the method parameters.
            createTopicRequest.Attributes = new Dictionary<string, string>
            {
                { "FifoTopic", "true" }
            };
            if (useContentBasedDeduplication)
            {
                createTopicRequest.Attributes.Add("ContentBasedDeduplication", "true");
            }
        }

        var createResponse = await _amazonSNSClient.CreateTopicAsync(createTopicRequest);
        return createResponse.TopicArn;
    }

For API details, see CreateTopic in AWS SDK for .NET API Reference.

The following code example shows how to use DeleteTopic.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Delete a topic by its topic ARN.


    /// <summary>
    /// Delete a topic by its topic ARN.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> DeleteTopicByArn(string topicArn)
    {
        var deleteResponse = await _amazonSNSClient.DeleteTopicAsync(
            new DeleteTopicRequest()
            {
                TopicArn = topicArn
            });
        return deleteResponse.HttpStatusCode == HttpStatusCode.OK;
    }

For API details, see DeleteTopic in AWS SDK for .NET API Reference.

The following code example shows how to use GetTopicAttributes.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.


    using System;
    using System.Collections.Generic;
    using System.Threading.Tasks;
    using Amazon.SimpleNotificationService;

    /// <summary>
    /// This example shows how to retrieve the attributes of an Amazon Simple
    /// Notification Service (Amazon SNS) topic.
    /// </summary>
    public class GetTopicAttributes
    {
        public static async Task Main()
        {
            string topicArn = "arn:aws:sns:us-west-2:000000000000:ExampleSNSTopic";
            IAmazonSimpleNotificationService client = new AmazonSimpleNotificationServiceClient();

            var attributes = await GetTopicAttributesAsync(client, topicArn);
            DisplayTopicAttributes(attributes);
        }

        /// <summary>
        /// Given the ARN of the Amazon SNS topic, this method retrieves the topic
        /// attributes.
        /// </summary>
        /// <param name="client">The initialized Amazon SNS client object used
        /// to retrieve the attributes for the Amazon SNS topic.</param>
        /// <param name="topicArn">The ARN of the topic for which to retrieve
        /// the attributes.</param>
        /// <returns>A Dictionary of topic attributes.</returns>
        public static async Task<Dictionary<string, string>> GetTopicAttributesAsync(
            IAmazonSimpleNotificationService client,
            string topicArn)
        {
            var response = await client.GetTopicAttributesAsync(topicArn);

            return response.Attributes;
        }

        /// <summary>
        /// This method displays the attributes for an Amazon SNS topic.
        /// </summary>
        /// <param name="topicAttributes">A Dictionary containing the
        /// attributes for an Amazon SNS topic.</param>
        public static void DisplayTopicAttributes(Dictionary<string, string> topicAttributes)
        {
            foreach (KeyValuePair<string, string> entry in topicAttributes)
            {
                Console.WriteLine($"{entry.Key}: {entry.Value}\n");
            }
        }
    }

For API details, see GetTopicAttributes in AWS SDK for .NET API Reference.

The following code example shows how to use ListSubscriptions.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.


    using System;
    using System.Collections.Generic;
    using System.Threading.Tasks;
    using Amazon.SimpleNotificationService;
    using Amazon.SimpleNotificationService.Model;

    /// <summary>
    /// This example will retrieve a list of the existing Amazon Simple
    /// Notification Service (Amazon SNS) subscriptions.
    /// </summary>
    public class ListSubscriptions
    {
        public static async Task Main()
        {
            IAmazonSimpleNotificationService client = new AmazonSimpleNotificationServiceClient();

            Console.WriteLine("Enter a topic ARN to list subscriptions for a specific topic, " +
                              "or press Enter to list subscriptions for all topics.");
            var topicArn = Console.ReadLine();
            Console.WriteLine();

            var subscriptions = await GetSubscriptionsListAsync(client, topicArn);

            DisplaySubscriptionList(subscriptions);
        }

        /// <summary>
        /// Gets a list of the existing Amazon SNS subscriptions, optionally by specifying a topic ARN.
        /// </summary>
        /// <param name="client">The initialized Amazon SNS client object used
        /// to obtain the list of subscriptions.</param>
        /// <param name="topicArn">The optional ARN of a specific topic. Defaults to null.</param>
        /// <returns>A list containing information about each subscription.</returns>
        public static async Task<List<Subscription>> GetSubscriptionsListAsync(IAmazonSimpleNotificationService client, string topicArn = null)
        {
            var results = new List<Subscription>();

            if (!string.IsNullOrEmpty(topicArn))
            {
                var paginateByTopic = client.Paginators.ListSubscriptionsByTopic(
                    new ListSubscriptionsByTopicRequest()
                    {
                        TopicArn = topicArn,
                    });

                // Get the entire list using the paginator.
                await foreach (var subscription in paginateByTopic.Subscriptions)
                {
                    results.Add(subscription);
                }
            }
            else
            {
                var paginateAllSubscriptions = client.Paginators.ListSubscriptions(new ListSubscriptionsRequest());

                // Get the entire list using the paginator.
                await foreach (var subscription in paginateAllSubscriptions.Subscriptions)
                {
                    results.Add(subscription);
                }
            }

            return results;
        }

        /// <summary>
        /// Display a list of Amazon SNS subscription information.
        /// </summary>
        /// <param name="subscriptionList">A list containing details for existing
        /// Amazon SNS subscriptions.</param>
        public static void DisplaySubscriptionList(List<Subscription> subscriptionList)
        {
            foreach (var subscription in subscriptionList)
            {
                Console.WriteLine($"Owner: {subscription.Owner}");
                Console.WriteLine($"Subscription ARN: {subscription.SubscriptionArn}");
                Console.WriteLine($"Topic ARN: {subscription.TopicArn}");
                Console.WriteLine($"Endpoint: {subscription.Endpoint}");
                Console.WriteLine($"Protocol: {subscription.Protocol}");
                Console.WriteLine();
            }
        }
    }

For API details, see ListSubscriptions in AWS SDK for .NET API Reference.

The following code example shows how to use ListTopics.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.


    using System;
    using System.Collections.Generic;
    using System.Threading.Tasks;
    using Amazon.SimpleNotificationService;
    using Amazon.SimpleNotificationService.Model;

    /// <summary>
    /// Lists the Amazon Simple Notification Service (Amazon SNS)
    /// topics for the current account.
    /// </summary>
    public class ListSNSTopics
    {
        public static async Task Main()
        {
            IAmazonSimpleNotificationService client = new AmazonSimpleNotificationServiceClient();

            await GetTopicListAsync(client);
        }

        /// <summary>
        /// Retrieves the list of Amazon SNS topics in groups of up to 100
        /// topics.
        /// </summary>
        /// <param name="client">The initialized Amazon SNS client object used
        /// to retrieve the list of topics.</param>
        public static async Task GetTopicListAsync(IAmazonSimpleNotificationService client)
        {
            // If there are more than 100 Amazon SNS topics, the call to
            // ListTopicsAsync will return a value to pass to the
            // method to retrieve the next 100 (or less) topics.
            string nextToken = string.Empty;

            do
            {
                var response = await client.ListTopicsAsync(nextToken);
                DisplayTopicsList(response.Topics);
                nextToken = response.NextToken;
            }
            while (!string.IsNullOrEmpty(nextToken));
        }

        /// <summary>
        /// Displays the list of Amazon SNS Topic ARNs.
        /// </summary>
        /// <param name="topicList">The list of Topic ARNs.</param>
        public static void DisplayTopicsList(List<Topic> topicList)
        {
            foreach (var topic in topicList)
            {
                Console.WriteLine($"{topic.TopicArn}");
            }
        }
    }

For API details, see ListTopics in AWS SDK for .NET API Reference.

The following code example shows how to use Publish.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Publish a message to a topic.


    using System;
    using System.Threading.Tasks;
    using Amazon.SimpleNotificationService;
    using Amazon.SimpleNotificationService.Model;

    /// <summary>
    /// This example publishes a message to an Amazon Simple Notification
    /// Service (Amazon SNS) topic.
    /// </summary>
    public class PublishToSNSTopic
    {
        public static async Task Main()
        {
            string topicArn = "arn:aws:sns:us-east-2:000000000000:ExampleSNSTopic";
            string messageText = "This is an example message to publish to the ExampleSNSTopic.";

            IAmazonSimpleNotificationService client = new AmazonSimpleNotificationServiceClient();

            await PublishToTopicAsync(client, topicArn, messageText);
        }

        /// <summary>
        /// Publishes a message to an Amazon SNS topic.
        /// </summary>
        /// <param name="client">The initialized client object used to publish
        /// to the Amazon SNS topic.</param>
        /// <param name="topicArn">The ARN of the topic.</param>
        /// <param name="messageText">The text of the message.</param>
        public static async Task PublishToTopicAsync(
            IAmazonSimpleNotificationService client,
            string topicArn,
            string messageText)
        {
            var request = new PublishRequest
            {
                TopicArn = topicArn,
                Message = messageText,
            };

            var response = await client.PublishAsync(request);

            Console.WriteLine($"Successfully published message ID: {response.MessageId}");
        }
    }

Publish a message to a topic with group, duplication, and attribute options.


    /// <summary>
    /// Publish messages using user settings.
    /// </summary>
    /// <returns>Async task.</returns>
    public static async Task PublishMessages()
    {
        Console.WriteLine("Now we can publish messages.");

        var keepSendingMessages = true;
        string? deduplicationId = null;
        string? toneAttribute = null;
        while (keepSendingMessages)
        {
            Console.WriteLine();
            var message = GetUserResponse("Enter a message to publish.", "This is a sample message");

            if (_useFifoTopic)
            {
                Console.WriteLine("Because you are using a FIFO topic, you must set a message group ID." +
                                  "\r\nAll messages within the same group will be received in the order " +
                                  "they were published.");

                Console.WriteLine();
                var messageGroupId = GetUserResponse("Enter a message group ID for this message:", "1");

                if (!_useContentBasedDeduplication)
                {
                    Console.WriteLine("Because you are not using content-based deduplication, " +
                                      "you must enter a deduplication ID.");

                    Console.WriteLine("Enter a deduplication ID for this message.");
                    deduplicationId = GetUserResponse("Enter a deduplication ID for this message.", "1");
                }

                if (GetYesNoResponse("Add an attribute to this message?"))
                {
                    Console.WriteLine("Enter a number for an attribute.");
                    for (int i = 0; i < _tones.Length; i++)
                    {
                        Console.WriteLine($"\t{i + 1}. {_tones[i]}");
                    }

                    var selection = GetUserResponse("", "1");
                    int.TryParse(selection, out var selectionNumber);

                    if (selectionNumber > 0 && selectionNumber < _tones.Length)
                    {
                        toneAttribute = _tones[selectionNumber - 1];
                    }
                }

                var messageID = await SnsWrapper.PublishToTopicWithAttribute(
                    _topicArn, message, "tone", toneAttribute, deduplicationId, messageGroupId);

                Console.WriteLine($"Message published with id {messageID}.");
            }

            keepSendingMessages = GetYesNoResponse("Send another message?", false);
        }
    }

Apply the user's selections to the publish action.


    /// <summary>
    /// Publish a message to a topic with an attribute and optional deduplication and group IDs.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <param name="message">The message to publish.</param>
    /// <param name="attributeName">The optional attribute for the message.</param>
    /// <param name="attributeValue">The optional attribute value for the message.</param>
    /// <param name="deduplicationId">The optional deduplication ID for the message.</param>
    /// <param name="groupId">The optional group ID for the message.</param>
    /// <returns>The ID of the message published.</returns>
    public async Task<string> PublishToTopicWithAttribute(
        string topicArn,
        string message,
        string? attributeName = null,
        string? attributeValue = null,
        string? deduplicationId = null,
        string? groupId = null)
    {
        var publishRequest = new PublishRequest()
        {
            TopicArn = topicArn,
            Message = message,
            MessageDeduplicationId = deduplicationId,
            MessageGroupId = groupId
        };

        if (attributeValue != null)
        {
            // Add the string attribute if it exists.
            publishRequest.MessageAttributes =
                new Dictionary<string, MessageAttributeValue>
                {
                    { attributeName!, new MessageAttributeValue() { StringValue = attributeValue, DataType = "String"} }
                };
        }

        var publishResponse = await _amazonSNSClient.PublishAsync(publishRequest);
        return publishResponse.MessageId;
    }

For API details, see Publish in AWS SDK for .NET API Reference.

The following code example shows how to use Subscribe.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Subscribe an email address to a topic.



        /// <summary>
        /// Creates a new subscription to a topic.
        /// </summary>
        /// <param name="client">The initialized Amazon SNS client object, used
        /// to create an Amazon SNS subscription.</param>
        /// <param name="topicArn">The ARN of the topic to subscribe to.</param>
        /// <returns>A SubscribeResponse object which includes the subscription
        /// ARN for the new subscription.</returns>
        public static async Task<SubscribeResponse> TopicSubscribeAsync(
            IAmazonSimpleNotificationService client,
            string topicArn)
        {
            SubscribeRequest request = new SubscribeRequest()
            {
                TopicArn = topicArn,
                ReturnSubscriptionArn = true,
                Protocol = "email",
                Endpoint = "recipient@example.com",
            };

            var response = await client.SubscribeAsync(request);

            return response;
        }

Subscribe a queue to a topic with optional filters.


    /// <summary>
    /// Subscribe a queue to a topic with optional filters.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <param name="useFifoTopic">The optional filtering policy for the subscription.</param>
    /// <param name="queueArn">The ARN of the queue.</param>
    /// <returns>The ARN of the new subscription.</returns>
    public async Task<string> SubscribeTopicWithFilter(string topicArn, string? filterPolicy, string queueArn)
    {
        var subscribeRequest = new SubscribeRequest()
        {
            TopicArn = topicArn,
            Protocol = "sqs",
            Endpoint = queueArn
        };

        if (!string.IsNullOrEmpty(filterPolicy))
        {
            subscribeRequest.Attributes = new Dictionary<string, string> { { "FilterPolicy", filterPolicy } };
        }

        var subscribeResponse = await _amazonSNSClient.SubscribeAsync(subscribeRequest);
        return subscribeResponse.SubscriptionArn;
    }

For API details, see Subscribe in AWS SDK for .NET API Reference.

The following code example shows how to use Unsubscribe.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Unsubscribe from a topic by a subscription ARN.


    /// <summary>
    /// Unsubscribe from a topic by a subscription ARN.
    /// </summary>
    /// <param name="subscriptionArn">The ARN of the subscription.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> UnsubscribeByArn(string subscriptionArn)
    {
        var unsubscribeResponse = await _amazonSNSClient.UnsubscribeAsync(
            new UnsubscribeRequest()
            {
                SubscriptionArn = subscriptionArn
            });
        return unsubscribeResponse.HttpStatusCode == HttpStatusCode.OK;
    }

For API details, see Unsubscribe in AWS SDK for .NET API Reference.

Scenarios

The following code example shows how to create an application that has subscription and publish functionality and translates messages.

AWS SDK for .NET

Shows how to use the Amazon Simple Notification Service .NET API to create a web application that has subscription and publish functionality. In addition, this example application also translates messages.

For complete source code and instructions on how to set up and run, see the full example on GitHub.

Services used in this example

Amazon SNS
Amazon Translate

The following code example shows how to create a serverless application that lets users manage photos using labels.

AWS SDK for .NET

Shows how to develop a photo asset management application that detects labels in images using Amazon Rekognition and stores them for later retrieval.

For complete source code and instructions on how to set up and run, see the full example on GitHub.

For a deep dive into the origin of this example see the post on AWS Community.

Services used in this example

API Gateway
DynamoDB
Lambda
Amazon Rekognition
Amazon S3
Amazon SNS

The following code example shows how to publish SMS messages using Amazon SNS.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.


namespace SNSMessageExample
{
    using System;
    using System.Threading.Tasks;
    using Amazon;
    using Amazon.SimpleNotificationService;
    using Amazon.SimpleNotificationService.Model;

    public class SNSMessage
    {
        private AmazonSimpleNotificationServiceClient snsClient;

        /// <summary>
        /// Initializes a new instance of the <see cref="SNSMessage"/> class.
        /// Constructs a new SNSMessage object initializing the Amazon Simple
        /// Notification Service (Amazon SNS) client using the supplied
        /// Region endpoint.
        /// </summary>
        /// <param name="regionEndpoint">The Amazon Region endpoint to use in
        /// sending test messages with this object.</param>
        public SNSMessage(RegionEndpoint regionEndpoint)
        {
            snsClient = new AmazonSimpleNotificationServiceClient(regionEndpoint);
        }

        /// <summary>
        /// Sends the SMS message passed in the text parameter to the phone number
        /// in phoneNum.
        /// </summary>
        /// <param name="phoneNum">The ten-digit phone number to which the text
        /// message will be sent.</param>
        /// <param name="text">The text of the message to send.</param>
        /// <returns>Async task.</returns>
        public async Task SendTextMessageAsync(string phoneNum, string text)
        {
            if (string.IsNullOrEmpty(phoneNum) || string.IsNullOrEmpty(text))
            {
                return;
            }

            // Now actually send the message.
            var request = new PublishRequest
            {
                Message = text,
                PhoneNumber = phoneNum,
            };

            try
            {
                var response = await snsClient.PublishAsync(request);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error sending message: {ex}");
            }
        }
    }
}

For API details, see Publish in AWS SDK for .NET API Reference.

The following code example shows how to:

Create topic (FIFO or non-FIFO).
Subscribe several queues to the topic with an option to apply a filter.
Publish messages to the topic.
Poll the queues for messages received.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Run an interactive scenario at a command prompt.


/// <summary>
/// Console application to run a workflow scenario for topics and queues.
/// </summary>
public static class TopicsAndQueues
{
    private static bool _useFifoTopic = false;
    private static bool _useContentBasedDeduplication = false;
    private static string _topicName = null!;
    private static string _topicArn = null!;

    private static readonly int _queueCount = 2;
    private static readonly string[] _queueUrls = new string[_queueCount];
    private static readonly string[] _subscriptionArns = new string[_queueCount];
    private static readonly string[] _tones = { "cheerful", "funny", "serious", "sincere" };
    public static SNSWrapper SnsWrapper { get; set; } = null!;
    public static SQSWrapper SqsWrapper { get; set; } = null!;
    public static bool UseConsole { get; set; } = true;
    static async Task Main(string[] args)
    {
        // Set up dependency injection for Amazon EventBridge.
        using var host = Host.CreateDefaultBuilder(args)
            .ConfigureLogging(logging =>
                logging.AddFilter("System", LogLevel.Debug)
                    .AddFilter<DebugLoggerProvider>("Microsoft", LogLevel.Information)
                    .AddFilter<ConsoleLoggerProvider>("Microsoft", LogLevel.Trace))
            .ConfigureServices((_, services) =>
                services.AddAWSService<IAmazonSQS>()
                    .AddAWSService<IAmazonSimpleNotificationService>()
                    .AddTransient<SNSWrapper>()
                    .AddTransient<SQSWrapper>()
            )
            .Build();

        ServicesSetup(host);
        PrintDescription();

        await RunScenario();

    }

    /// <summary>
    /// Populate the services for use within the console application.
    /// </summary>
    /// <param name="host">The services host.</param>
    private static void ServicesSetup(IHost host)
    {
        SnsWrapper = host.Services.GetRequiredService<SNSWrapper>();
        SqsWrapper = host.Services.GetRequiredService<SQSWrapper>();
    }

    /// <summary>
    /// Run the scenario for working with topics and queues.
    /// </summary>
    /// <returns>True if successful.</returns>
    public static async Task<bool> RunScenario()
    {
        try
        {
            await SetupTopic();

            await SetupQueues();

            await PublishMessages();

            foreach (var queueUrl in _queueUrls)
            {
                var messages = await PollForMessages(queueUrl);
                if (messages.Any())
                {
                    await DeleteMessages(queueUrl, messages);
                }
            }
            await CleanupResources();

            Console.WriteLine("Messaging with topics and queues workflow is complete.");
            return true;
        }
        catch (Exception ex)
        {
            Console.WriteLine(new string('-', 80));
            Console.WriteLine($"There was a problem running the scenario: {ex.Message}");
            await CleanupResources();
            Console.WriteLine(new string('-', 80));
            return false;
        }
    }

    /// <summary>
    /// Print a description for the tasks in the workflow.
    /// </summary>
    /// <returns>Async task.</returns>
    private static void PrintDescription()
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine($"Welcome to messaging with topics and queues.");

        Console.WriteLine(new string('-', 80));
        Console.WriteLine($"In this workflow, you will create an SNS topic and subscribe {_queueCount} SQS queues to the topic." +
                          $"\r\nYou can select from several options for configuring the topic and the subscriptions for the 2 queues." +
                          $"\r\nYou can then post to the topic and see the results in the queues.\r\n");

        Console.WriteLine(new string('-', 80));
    }

    /// <summary>
    /// Set up the SNS topic to be used with the queues.
    /// </summary>
    /// <returns>Async task.</returns>
    private static async Task<string> SetupTopic()
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine($"SNS topics can be configured as FIFO (First-In-First-Out)." +
                          $"\r\nFIFO topics deliver messages in order and support deduplication and message filtering." +
                          $"\r\nYou can then post to the topic and see the results in the queues.\r\n");

        _useFifoTopic = GetYesNoResponse("Would you like to work with FIFO topics?");

        if (_useFifoTopic)
        {
            Console.WriteLine(new string('-', 80));
            _topicName = GetUserResponse("Enter a name for your SNS topic: ", "example-topic");
            Console.WriteLine(
                "Because you have selected a FIFO topic, '.fifo' must be appended to the topic name.\r\n");

            Console.WriteLine(new string('-', 80));
            Console.WriteLine($"Because you have chosen a FIFO topic, deduplication is supported." +
                              $"\r\nDeduplication IDs are either set in the message or automatically generated " +
                              $"\r\nfrom content using a hash function.\r\n" +
                              $"\r\nIf a message is successfully published to an SNS FIFO topic, any message " +
                              $"\r\npublished and determined to have the same deduplication ID, " +
                              $"\r\nwithin the five-minute deduplication interval, is accepted but not delivered.\r\n" +
                              $"\r\nFor more information about deduplication, " +
                              $"\r\nsee https://docs.aws.amazon.com/sns/latest/dg/fifo-message-dedup.html.");

            _useContentBasedDeduplication = GetYesNoResponse("Use content-based deduplication instead of entering a deduplication ID?");
            Console.WriteLine(new string('-', 80));
        }

        _topicArn = await SnsWrapper.CreateTopicWithName(_topicName, _useFifoTopic, _useContentBasedDeduplication);

        Console.WriteLine($"Your new topic with the name {_topicName}" +
                          $"\r\nand Amazon Resource Name (ARN) {_topicArn}" +
                          $"\r\nhas been created.\r\n");

        Console.WriteLine(new string('-', 80));
        return _topicArn;
    }

    /// <summary>
    /// Set up the queues.
    /// </summary>
    /// <returns>Async task.</returns>
    private static async Task SetupQueues()
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine($"Now you will create {_queueCount} Amazon Simple Queue Service (Amazon SQS) queues to subscribe to the topic.");

        // Repeat this section for each queue.
        for (int i = 0; i < _queueCount; i++)
        {
            var queueName = GetUserResponse("Enter a name for an Amazon SQS queue: ", $"example-queue-{i}");
            if (_useFifoTopic)
            {
                // Only explain this once.
                if (i == 0)
                {
                    Console.WriteLine(
                        "Because you have selected a FIFO topic, '.fifo' must be appended to the queue name.");
                }

                var queueUrl = await SqsWrapper.CreateQueueWithName(queueName, _useFifoTopic);

                _queueUrls[i] = queueUrl;

                Console.WriteLine($"Your new queue with the name {queueName}" +
                                  $"\r\nand queue URL {queueUrl}" +
                                  $"\r\nhas been created.\r\n");

                if (i == 0)
                {
                    Console.WriteLine(
                        $"The queue URL is used to retrieve the queue ARN,\r\n" +
                        $"which is used to create a subscription.");
                    Console.WriteLine(new string('-', 80));
                }

                var queueArn = await SqsWrapper.GetQueueArnByUrl(queueUrl);

                if (i == 0)
                {
                    Console.WriteLine(
                        $"An AWS Identity and Access Management (IAM) policy must be attached to an SQS queue, enabling it to receive\r\n" +
                        $"messages from an SNS topic");
                }

                await SqsWrapper.SetQueuePolicyForTopic(queueArn, _topicArn, queueUrl);

                await SetupFilters(i, queueArn, queueName);
            }
        }

        Console.WriteLine(new string('-', 80));
    }

    /// <summary>
    /// Set up filters with user options for a queue.
    /// </summary>
    /// <param name="queueCount">The number of this queue.</param>
    /// <param name="queueArn">The ARN of the queue.</param>
    /// <param name="queueName">The name of the queue.</param>
    /// <returns>Async Task.</returns>
    public static async Task SetupFilters(int queueCount, string queueArn, string queueName)
    {
        if (_useFifoTopic)
        {
            Console.WriteLine(new string('-', 80));
            // Only explain this once.
            if (queueCount == 0)
            {
                Console.WriteLine(
                    "Subscriptions to a FIFO topic can have filters." +
                    "If you add a filter to this subscription, then only the filtered messages " +
                    "will be received in the queue.");

                Console.WriteLine(
                    "For information about message filtering, " +
                    "see https://docs.aws.amazon.com/sns/latest/dg/sns-message-filtering.html");

                Console.WriteLine(
                    "For this example, you can filter messages by a" +
                    "TONE attribute.");
            }

            var useFilter = GetYesNoResponse($"Filter messages for {queueName}'s subscription to the topic?");

            string? filterPolicy = null;
            if (useFilter)
            {
                filterPolicy = CreateFilterPolicy();
            }
            var subscriptionArn = await SnsWrapper.SubscribeTopicWithFilter(_topicArn, filterPolicy,
                queueArn);
            _subscriptionArns[queueCount] = subscriptionArn;

            Console.WriteLine(
                $"The queue {queueName} has been subscribed to the topic {_topicName} " +
                $"with the subscription ARN {subscriptionArn}");
            Console.WriteLine(new string('-', 80));
        }
    }

    /// <summary>
    /// Use user input to create a filter policy for a subscription.
    /// </summary>
    /// <returns>The serialized filter policy.</returns>
    public static string CreateFilterPolicy()
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine(
            $"You can filter messages by one or more of the following" +
            $"TONE attributes.");

        List<string> filterSelections = new List<string>();

        var selectionNumber = 0;
        do
        {
            Console.WriteLine(
                $"Enter a number to add a TONE filter, or enter 0 to stop adding filters.");
            for (int i = 0; i < _tones.Length; i++)
            {
                Console.WriteLine($"\t{i + 1}. {_tones[i]}");
            }

            var selection = GetUserResponse("", filterSelections.Any() ? "0" : "1");
            int.TryParse(selection, out selectionNumber);
            if (selectionNumber > 0 && !filterSelections.Contains(_tones[selectionNumber - 1]))
            {
                filterSelections.Add(_tones[selectionNumber - 1]);
            }
        } while (selectionNumber != 0);

        var filters = new Dictionary<string, List<string>>
        {
            { "tone", filterSelections }
        };
        string filterPolicy = JsonSerializer.Serialize(filters);
        return filterPolicy;
    }

    /// <summary>
    /// Publish messages using user settings.
    /// </summary>
    /// <returns>Async task.</returns>
    public static async Task PublishMessages()
    {
        Console.WriteLine("Now we can publish messages.");

        var keepSendingMessages = true;
        string? deduplicationId = null;
        string? toneAttribute = null;
        while (keepSendingMessages)
        {
            Console.WriteLine();
            var message = GetUserResponse("Enter a message to publish.", "This is a sample message");

            if (_useFifoTopic)
            {
                Console.WriteLine("Because you are using a FIFO topic, you must set a message group ID." +
                                  "\r\nAll messages within the same group will be received in the order " +
                                  "they were published.");

                Console.WriteLine();
                var messageGroupId = GetUserResponse("Enter a message group ID for this message:", "1");

                if (!_useContentBasedDeduplication)
                {
                    Console.WriteLine("Because you are not using content-based deduplication, " +
                                      "you must enter a deduplication ID.");

                    Console.WriteLine("Enter a deduplication ID for this message.");
                    deduplicationId = GetUserResponse("Enter a deduplication ID for this message.", "1");
                }

                if (GetYesNoResponse("Add an attribute to this message?"))
                {
                    Console.WriteLine("Enter a number for an attribute.");
                    for (int i = 0; i < _tones.Length; i++)
                    {
                        Console.WriteLine($"\t{i + 1}. {_tones[i]}");
                    }

                    var selection = GetUserResponse("", "1");
                    int.TryParse(selection, out var selectionNumber);

                    if (selectionNumber > 0 && selectionNumber < _tones.Length)
                    {
                        toneAttribute = _tones[selectionNumber - 1];
                    }
                }

                var messageID = await SnsWrapper.PublishToTopicWithAttribute(
                    _topicArn, message, "tone", toneAttribute, deduplicationId, messageGroupId);

                Console.WriteLine($"Message published with id {messageID}.");
            }

            keepSendingMessages = GetYesNoResponse("Send another message?", false);
        }
    }

    /// <summary>
    /// Poll for the published messages to see the results of the user's choices.
    /// </summary>
    /// <returns>Async task.</returns>
    public static async Task<List<Message>> PollForMessages(string queueUrl)
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine($"Now the SQS queue at {queueUrl} will be polled to retrieve the messages." +
                          "\r\nPress any key to continue.");
        if (UseConsole)
        {
            Console.ReadLine();
        }

        var moreMessages = true;
        var messages = new List<Message>();
        while (moreMessages)
        {
            var newMessages = await SqsWrapper.ReceiveMessagesByUrl(queueUrl, 10);

            moreMessages = newMessages.Any();
            if (moreMessages)
            {
                messages.AddRange(newMessages);
            }
        }

        Console.WriteLine($"{messages.Count} message(s) were received by the queue at {queueUrl}.");

        foreach (var message in messages)
        {
            Console.WriteLine("\tMessage:" +
                              $"\n\t{message.Body}");
        }

        Console.WriteLine(new string('-', 80));
        return messages;
    }

    /// <summary>
    /// Delete the message using handles in a batch.
    /// </summary>
    /// <returns>Async task.</returns>
    public static async Task DeleteMessages(string queueUrl, List<Message> messages)
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine("Now we can delete the messages in this queue in a batch.");
        await SqsWrapper.DeleteMessageBatchByUrl(queueUrl, messages);
        Console.WriteLine(new string('-', 80));
    }

    /// <summary>
    /// Clean up the resources from the scenario.
    /// </summary>
    /// <returns>Async task.</returns>
    private static async Task CleanupResources()
    {
        Console.WriteLine(new string('-', 80));
        Console.WriteLine($"Clean up resources.");

        try
        {
            foreach (var queueUrl in _queueUrls)
            {
                if (!string.IsNullOrEmpty(queueUrl))
                {
                    var deleteQueue =
                        GetYesNoResponse($"Delete queue with url {queueUrl}?");
                    if (deleteQueue)
                    {
                        await SqsWrapper.DeleteQueueByUrl(queueUrl);
                    }
                }
            }

            foreach (var subscriptionArn in _subscriptionArns)
            {
                if (!string.IsNullOrEmpty(subscriptionArn))
                {
                    await SnsWrapper.UnsubscribeByArn(subscriptionArn);
                }
            }

            var deleteTopic = GetYesNoResponse($"Delete topic {_topicName}?");
            if (deleteTopic)
            {
                await SnsWrapper.DeleteTopicByArn(_topicArn);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Unable to clean up resources. Here's why: {ex.Message}.");
        }

        Console.WriteLine(new string('-', 80));
    }

    /// <summary>
    /// Helper method to get a yes or no response from the user.
    /// </summary>
    /// <param name="question">The question string to print on the console.</param>
    /// <param name="defaultAnswer">Optional default answer to use.</param>
    /// <returns>True if the user responds with a yes.</returns>
    private static bool GetYesNoResponse(string question, bool defaultAnswer = true)
    {
        if (UseConsole)
        {
            Console.WriteLine(question);
            var ynResponse = Console.ReadLine();
            var response = ynResponse != null &&
                           ynResponse.Equals("y",
                               StringComparison.InvariantCultureIgnoreCase);
            return response;
        }
        // If not using the console, use the default.
        return defaultAnswer;
    }

    /// <summary>
    /// Helper method to get a string response from the user through the console.
    /// </summary>
    /// <param name="question">The question string to print on the console.</param>
    /// <param name="defaultAnswer">Optional default answer to use.</param>
    /// <returns>True if the user responds with a yes.</returns>
    private static string GetUserResponse(string question, string defaultAnswer)
    {
        if (UseConsole)
        {
            var response = "";
            while (string.IsNullOrEmpty(response))
            {
                Console.WriteLine(question);
                response = Console.ReadLine();
            }
            return response;
        }
        // If not using the console, use the default.
        return defaultAnswer;
    }
}

Create a class that wraps Amazon SQS operations.



/// <summary>
/// Wrapper for Amazon Simple Queue Service (SQS) operations.
/// </summary>
public class SQSWrapper
{
    private readonly IAmazonSQS _amazonSQSClient;

    /// <summary>
    /// Constructor for the Amazon SQS wrapper.
    /// </summary>
    /// <param name="amazonSQS">The injected Amazon SQS client.</param>
    public SQSWrapper(IAmazonSQS amazonSQS)
    {
        _amazonSQSClient = amazonSQS;
    }

    /// <summary>
    /// Create a queue with a specific name.
    /// </summary>
    /// <param name="queueName">The name for the queue.</param>
    /// <param name="useFifoQueue">True to use a FIFO queue.</param>
    /// <returns>The url for the queue.</returns>
    public async Task<string> CreateQueueWithName(string queueName, bool useFifoQueue)
    {
        int maxMessage = 256 * 1024;
        var queueAttributes = new Dictionary<string, string>
        {
            {
                QueueAttributeName.MaximumMessageSize,
                maxMessage.ToString()
            }
        };

        var createQueueRequest = new CreateQueueRequest()
        {
            QueueName = queueName,
            Attributes = queueAttributes
        };

        if (useFifoQueue)
        {
            // Update the name if it is not correct for a FIFO queue.
            if (!queueName.EndsWith(".fifo"))
            {
                createQueueRequest.QueueName = queueName + ".fifo";
            }

            // Add an attribute for a FIFO queue.
            createQueueRequest.Attributes.Add(
                QueueAttributeName.FifoQueue, "true");
        }

        var createResponse = await _amazonSQSClient.CreateQueueAsync(
            new CreateQueueRequest()
            {
                QueueName = queueName
            });
        return createResponse.QueueUrl;
    }

    /// <summary>
    /// Get the ARN for a queue from its URL.
    /// </summary>
    /// <param name="queueUrl">The URL of the queue.</param>
    /// <returns>The ARN of the queue.</returns>
    public async Task<string> GetQueueArnByUrl(string queueUrl)
    {
        var getAttributesRequest = new GetQueueAttributesRequest()
        {
            QueueUrl = queueUrl,
            AttributeNames = new List<string>() { QueueAttributeName.QueueArn }
        };

        var getAttributesResponse = await _amazonSQSClient.GetQueueAttributesAsync(
            getAttributesRequest);

        return getAttributesResponse.QueueARN;
    }

    /// <summary>
    /// Set the policy attribute of a queue for a topic.
    /// </summary>
    /// <param name="queueArn">The ARN of the queue.</param>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <param name="queueUrl">The url for the queue.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> SetQueuePolicyForTopic(string queueArn, string topicArn, string queueUrl)
    {
        var queuePolicy = "{" +
                                "\"Version\": \"2012-10-17\"," +
                                "\"Statement\": [{" +
                                     "\"Effect\": \"Allow\"," +
                                     "\"Principal\": {" +
                                         $"\"Service\": " +
                                             "\"sns.amazonaws.com\"" +
                                            "}," +
                                     "\"Action\": \"sqs:SendMessage\"," +
                                     $"\"Resource\": \"{queueArn}\"," +
                                      "\"Condition\": {" +
                                           "\"ArnEquals\": {" +
                                                $"\"aws:SourceArn\": \"{topicArn}\"" +
                                            "}" +
                                        "}" +
                                "}]" +
                             "}";
        var attributesResponse = await _amazonSQSClient.SetQueueAttributesAsync(
            new SetQueueAttributesRequest()
            {
                QueueUrl = queueUrl,
                Attributes = new Dictionary<string, string>() { { "Policy", queuePolicy } }
            });
        return attributesResponse.HttpStatusCode == HttpStatusCode.OK;
    }

    /// <summary>
    /// Receive messages from a queue by its URL.
    /// </summary>
    /// <param name="queueUrl">The url of the queue.</param>
    /// <returns>The list of messages.</returns>
    public async Task<List<Message>> ReceiveMessagesByUrl(string queueUrl, int maxMessages)
    {
        // Setting WaitTimeSeconds to non-zero enables long polling.
        // For information about long polling, see
        // https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-short-and-long-polling.html
        var messageResponse = await _amazonSQSClient.ReceiveMessageAsync(
            new ReceiveMessageRequest()
            {
                QueueUrl = queueUrl,
                MaxNumberOfMessages = maxMessages,
                WaitTimeSeconds = 1
            });
        return messageResponse.Messages;
    }

    /// <summary>
    /// Delete a batch of messages from a queue by its url.
    /// </summary>
    /// <param name="queueUrl">The url of the queue.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> DeleteMessageBatchByUrl(string queueUrl, List<Message> messages)
    {
        var deleteRequest = new DeleteMessageBatchRequest()
        {
            QueueUrl = queueUrl,
            Entries = new List<DeleteMessageBatchRequestEntry>()
        };
        foreach (var message in messages)
        {
            deleteRequest.Entries.Add(new DeleteMessageBatchRequestEntry()
            {
                ReceiptHandle = message.ReceiptHandle,
                Id = message.MessageId
            });
        }

        var deleteResponse = await _amazonSQSClient.DeleteMessageBatchAsync(deleteRequest);

        return deleteResponse.Failed.Any();
    }

    /// <summary>
    /// Delete a queue by its URL.
    /// </summary>
    /// <param name="queueUrl">The url of the queue.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> DeleteQueueByUrl(string queueUrl)
    {
        var deleteResponse = await _amazonSQSClient.DeleteQueueAsync(
            new DeleteQueueRequest()
            {
                QueueUrl = queueUrl
            });
        return deleteResponse.HttpStatusCode == HttpStatusCode.OK;
    }
}

Create a class that wraps Amazon SNS operations.



/// <summary>
/// Wrapper for Amazon Simple Notification Service (SNS) operations.
/// </summary>
public class SNSWrapper
{
    private readonly IAmazonSimpleNotificationService _amazonSNSClient;

    /// <summary>
    /// Constructor for the Amazon SNS wrapper.
    /// </summary>
    /// <param name="amazonSQS">The injected Amazon SNS client.</param>
    public SNSWrapper(IAmazonSimpleNotificationService amazonSNS)
    {
        _amazonSNSClient = amazonSNS;
    }

    /// <summary>
    /// Create a new topic with a name and specific FIFO and de-duplication attributes.
    /// </summary>
    /// <param name="topicName">The name for the topic.</param>
    /// <param name="useFifoTopic">True to use a FIFO topic.</param>
    /// <param name="useContentBasedDeduplication">True to use content-based de-duplication.</param>
    /// <returns>The ARN of the new topic.</returns>
    public async Task<string> CreateTopicWithName(string topicName, bool useFifoTopic, bool useContentBasedDeduplication)
    {
        var createTopicRequest = new CreateTopicRequest()
        {
            Name = topicName,
        };

        if (useFifoTopic)
        {
            // Update the name if it is not correct for a FIFO topic.
            if (!topicName.EndsWith(".fifo"))
            {
                createTopicRequest.Name = topicName + ".fifo";
            }

            // Add the attributes from the method parameters.
            createTopicRequest.Attributes = new Dictionary<string, string>
            {
                { "FifoTopic", "true" }
            };
            if (useContentBasedDeduplication)
            {
                createTopicRequest.Attributes.Add("ContentBasedDeduplication", "true");
            }
        }

        var createResponse = await _amazonSNSClient.CreateTopicAsync(createTopicRequest);
        return createResponse.TopicArn;
    }

    /// <summary>
    /// Subscribe a queue to a topic with optional filters.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <param name="useFifoTopic">The optional filtering policy for the subscription.</param>
    /// <param name="queueArn">The ARN of the queue.</param>
    /// <returns>The ARN of the new subscription.</returns>
    public async Task<string> SubscribeTopicWithFilter(string topicArn, string? filterPolicy, string queueArn)
    {
        var subscribeRequest = new SubscribeRequest()
        {
            TopicArn = topicArn,
            Protocol = "sqs",
            Endpoint = queueArn
        };

        if (!string.IsNullOrEmpty(filterPolicy))
        {
            subscribeRequest.Attributes = new Dictionary<string, string> { { "FilterPolicy", filterPolicy } };
        }

        var subscribeResponse = await _amazonSNSClient.SubscribeAsync(subscribeRequest);
        return subscribeResponse.SubscriptionArn;
    }

    /// <summary>
    /// Publish a message to a topic with an attribute and optional deduplication and group IDs.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <param name="message">The message to publish.</param>
    /// <param name="attributeName">The optional attribute for the message.</param>
    /// <param name="attributeValue">The optional attribute value for the message.</param>
    /// <param name="deduplicationId">The optional deduplication ID for the message.</param>
    /// <param name="groupId">The optional group ID for the message.</param>
    /// <returns>The ID of the message published.</returns>
    public async Task<string> PublishToTopicWithAttribute(
        string topicArn,
        string message,
        string? attributeName = null,
        string? attributeValue = null,
        string? deduplicationId = null,
        string? groupId = null)
    {
        var publishRequest = new PublishRequest()
        {
            TopicArn = topicArn,
            Message = message,
            MessageDeduplicationId = deduplicationId,
            MessageGroupId = groupId
        };

        if (attributeValue != null)
        {
            // Add the string attribute if it exists.
            publishRequest.MessageAttributes =
                new Dictionary<string, MessageAttributeValue>
                {
                    { attributeName!, new MessageAttributeValue() { StringValue = attributeValue, DataType = "String"} }
                };
        }

        var publishResponse = await _amazonSNSClient.PublishAsync(publishRequest);
        return publishResponse.MessageId;
    }


    /// <summary>
    /// Unsubscribe from a topic by a subscription ARN.
    /// </summary>
    /// <param name="subscriptionArn">The ARN of the subscription.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> UnsubscribeByArn(string subscriptionArn)
    {
        var unsubscribeResponse = await _amazonSNSClient.UnsubscribeAsync(
            new UnsubscribeRequest()
            {
                SubscriptionArn = subscriptionArn
            });
        return unsubscribeResponse.HttpStatusCode == HttpStatusCode.OK;
    }

    /// <summary>
    /// Delete a topic by its topic ARN.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> DeleteTopicByArn(string topicArn)
    {
        var deleteResponse = await _amazonSNSClient.DeleteTopicAsync(
            new DeleteTopicRequest()
            {
                TopicArn = topicArn
            });
        return deleteResponse.HttpStatusCode == HttpStatusCode.OK;
    }
}

For API details, see the following topics in AWS SDK for .NET API Reference.

Serverless examples

The following code example shows how to implement a Lambda function that receives an event triggered by receiving messages from an SNS topic. The function retrieves the messages from the event parameter and logs the content of each message.

AWS SDK for .NET

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the Serverless examples repository.

Consuming an SNS event with Lambda using .NET.


// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
using Amazon.Lambda.Core;
using Amazon.Lambda.SNSEvents;


// Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]

namespace SnsIntegration;

public class Function
{
    public async Task FunctionHandler(SNSEvent evnt, ILambdaContext context)
    {
        foreach (var record in evnt.Records)
        {
            await ProcessRecordAsync(record, context);
        }
        context.Logger.LogInformation("done");
    }

    private async Task ProcessRecordAsync(SNSEvent.SNSRecord record, ILambdaContext context)
    {
        try
        {
            context.Logger.LogInformation($"Processed record {record.Sns.Message}");

            // TODO: Do interesting work based on the new message
            await Task.CompletedTask;
        }
        catch (Exception e)
        {
            //You can use Dead Letter Queue to handle failures. By configuring a Lambda DLQ.
            context.Logger.LogError($"An error occurred");
            throw;
        }
    }
}

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Document Conventions

Amazon SES API v2

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