Deferred Messages

INFO

Remember that you can download the samples from the GitHub repository.

This sample makes use of Shuttle.Esb.AzureStorageQueues for the message queues. Local Azure Storage Queues should be provided by Azurite.

Once you have opened the Shuttle.Deferred.sln solution in Visual Studio set the following projects as startup projects:

• Shuttle.Deferred.Client
• Shuttle.Deferred.Server

Implementation

Deferred messages refer to messages that are not immediately processed when available but are rather set to only process at a given future date.

In this guide we'll create the following projects:

• Shuttle.Deferred.Client (Console Application)
• Shuttle.Deferred.Server (Console Application)
• Shuttle.Deferred.Messages (Class Library)

Messages

Create a new class library called Shuttle.Deferred.Messages with a solution called Shuttle.Deferred

Note: remember to change the Solution name.

RegisterMember

Rename the Class1 default file to RegisterMember and add a UserName property.

namespace Shuttle.Deferred.Messages
{
	public class RegisterMember
	{
		public string UserName { get; set; }
	}
}

Client

Add a new Console Application to the solution called Shuttle.Deferred.Client.

Install the Shuttle.Esb.AzureStorageQueues nuget package.

This will provide access to the Azure Storage Queues IQueue implementation and also include the required dependencies.

Install the Microsoft.Extensions.Configuration.Json nuget package.

This will provide the ability to read the appsettings.json file.

Add a reference to the Shuttle.Deferred.Messages project.

Program

Implement the main client code as follows:

using System;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Shuttle.Deferred.Messages;
using Shuttle.Esb;
using Shuttle.Esb.AzureStorageQueues;

namespace Shuttle.Deferred.Client
{
    internal class Program
    {
        private static async Task Main(string[] args)
        {
            var services = new ServiceCollection();

            var configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();

            services.AddSingleton<IConfiguration>(configuration);

            services.AddServiceBus(builder =>
            {
                configuration.GetSection(ServiceBusOptions.SectionName).Bind(builder.Options);
            });

            services.AddAzureStorageQueues(builder =>
            {
                builder.AddOptions("azure", new AzureStorageQueueOptions
                {
                    ConnectionString = "UseDevelopmentStorage=true;"
                });
            });

            Console.WriteLine("Type some characters and then press [enter] to submit; an empty line submission stops execution:");
            Console.WriteLine();

            await using (var serviceBus = await services.BuildServiceProvider().GetRequiredService<IServiceBus>().StartAsync())
            {
                string userName;

                while (!string.IsNullOrEmpty(userName = Console.ReadLine()))
                {
                    await serviceBus.SendAsync(new RegisterMember
                    {
                        UserName = userName
                    }, builder => builder.Defer(DateTime.Now.AddSeconds(5)));
                }
            }
        }
    }
}

The message sent will have its IgnoreTilleDate (on the TransportMessage) set to 5 seconds into the future.

Client configuration file

Add an appsettings.json file as follows:

{
  "Shuttle": {
    "ServiceBus": {
      "MessageRoutes": [
        {
          "Uri": "azuresq://azure/shuttle-server-work",
          "Specifications": [
            {
              "Name": "StartsWith",
              "Value": "Shuttle.Deferred.Messages"
            }
          ]
        }
      ]
    }
  }
}

This tells the service bus that all messages sent having a type name starting with Shuttle.Deferred.Messages should be sent to endpoint azuresq://azure/shuttle-server-work.

Server

Add a new Console Application to the solution called Shuttle.Deferred.Server.

Install the Shuttle.Esb.AzureStorageQueues nuget package.

This will provide access to the Azure Storage Queues IQueue implementation and also include the required dependencies.

Install the Microsoft.Extensions.Hosting nuget package.

This allows a console application to be hosted using the .NET generic host.

Install the Microsoft.Extensions.Configuration.Json nuget package.

This will provide the ability to read the appsettings.json file.

Add a reference to the Shuttle.Deferred.Messages project.

Program

Implement the Program class as follows:

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Shuttle.Esb;
using Shuttle.Esb.AzureStorageQueues;

namespace Shuttle.Deferred.Server
{
    public class Programs
    {
        public static async Task Main()
        {
            await Host.CreateDefaultBuilder()
                .ConfigureServices(services =>
                {
                    var configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();

                    services.AddSingleton<IConfiguration>(configuration);

                    services.AddServiceBus(builder =>
                    {
                        configuration.GetSection(ServiceBusOptions.SectionName).Bind(builder.Options);

                        builder.Options.Asynchronous = true;
                    });

                    services.AddAzureStorageQueues(builder =>
                    {
                        builder.AddOptions("azure", new AzureStorageQueueOptions
                        {
                            ConnectionString = configuration.GetConnectionString("azure")
                        });
                    });
                })
                .Build()
                .RunAsync();
        }
    }
}

Server configuration file

Add an appsettings.json file as follows:

{
  "ConnectionStrings": {
    "azure": "UseDevelopmentStorage=true;"
  },
  "Shuttle": {
    "ServiceBus": {
      "Inbox": {
        "WorkQueueUri": "azuresq://azure/shuttle-server-work",
        "DeferredQueueUri": "azuresq://azure/shuttle-server-deferred",
        "ErrorQueueUri": "azuresq://azure/shuttle-error"
      }
    }
  }
}

RegisterMemberHandler

Add a new class called RegisterMemberHandler that implements the IMessageHandler<RegisterMember> interface as follows:

using System;
using Shuttle.Esb;
using Shuttle.Deferred.Messages;

namespace Shuttle.Deferred.Server
{
	public class RegisterMemberHandler : IAsyncMessageHandler<RegisterMember>
	{
	    public async Task ProcessMessageAsync(IHandlerContext<RegisterMember> context)
		{
		    Console.WriteLine($"[MEMBER REGISTERED] : user name = '{context.Message.UserName}'");

		    await Task.CompletedTask;
		}
	}
}

Run

Set both the client and server projects as the startup.

Execute

Execute the application.

The client application will wait for you to input a user name. For this example enter my user name and press enter:

INFO

After 5 seconds you will observe that the server application has processed the message.

You have now implemented deferred message sending.