Deferred Messages #

This sample makes use of Shuttle.Esb.AzureMQ 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.

RegisterMemberCommand #

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

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

Client #

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

Install the Shuttle.Esb.AzureMQ nuget package.

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

Install the Shuttle.Core.Autofac nuget package.

This will provide access to the Autofac dependency container implementation.

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

Program #

Implement the main client code as follows:

using System;
using Autofac;
using Shuttle.Core.Autofac;
using Shuttle.Core.Container;
using Shuttle.Deferred.Messages;
using Shuttle.Esb;
using Shuttle.Esb.AzureMQ;

namespace Shuttle.Deferred.Client
{
	internal class Program
	{
		private static void Main(string[] args)
		{
			var containerBuilder = new ContainerBuilder();
			var registry = new AutofacComponentRegistry(containerBuilder);

			registry.Register<IAzureStorageConfiguration, DefaultAzureStorageConfiguration>();
			registry.RegisterServiceBus();

			using (var bus = new AutofacComponentResolver(containerBuilder.Build()).Resolve<IServiceBus>().Start())
			{
				string userName;

				while (!string.IsNullOrEmpty(userName = Console.ReadLine()))
				{
					bus.Send(new RegisterMemberCommand
					{
						UserName = userName
					}, c => c.Defer(DateTime.Now.AddSeconds(5)));
				}
			}
		}
	}
}

The message sent will have its IgnoreTilleDate set to 5 seconds into the future. You can have a look at the [TransportMessage][transport-message] for more information on the message structure.

App.config #

Create the service bus configuration as follows:

<?xml version="1.0" encoding="utf-8"?>

<configuration>
	<configSections>
		<section name='serviceBus' type="Shuttle.Esb.ServiceBusSection, Shuttle.Esb" />
	</configSections>

	<appSettings>
		<add key="azure" value="UseDevelopmentStorage=true;" />
	</appSettings>

	<serviceBus>
		<messageRoutes>
			<messageRoute uri="azuremq://azure/shuttle-server-work">
				<add specification="StartsWith" value="Shuttle.Deferred.Messages" />
			</messageRoute>
		</messageRoutes>
	</serviceBus>
</configuration>

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

Server #

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

Install the Shuttle.Esb.AzureMQ nuget package.

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

Install the Shuttle.Core.WorkerService nuget package.

This allows a console application to be hosted as a Windows Service or Systemd Unit while running as a normal console application when debugging.

Install the Shuttle.Core.Autofac nuget package.

This will provide access to the Autofac dependency container implementation.

Install the Shuttle.Core.Log4Net nuget package.

We are also adding Log4Net to demonstrate how to add a third-party logging mechanism.

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

Program #

Implement the Program class as follows:

using Shuttle.Core.WorkerService;

namespace Shuttle.Deferred.Server
{
    public class Programs
    {
        public static void Main()
        {
            ServiceHost.Run<Host>();
        }
    }
}

Host #

Rename the default Class1 file to Host and implement the IServiceHost interface as follows:

using System.Text;
using Autofac;
using log4net;
using Shuttle.Core.Autofac;
using Shuttle.Core.Container;
using Shuttle.Core.Log4Net;
using Shuttle.Core.Logging;
using Shuttle.Core.WorkerService;
using Shuttle.Esb;
using Shuttle.Esb.AzureMQ;

namespace Shuttle.Deferred.Server
{
    public class Host : IServiceHost
    {
        private IServiceBus _bus;

        public void Stop()
        {
            _bus.Dispose();
        }

        public void Start()
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);

            Log.Assign(new Log4NetLog(LogManager.GetLogger(typeof(Host))));

            var containerBuilder = new ContainerBuilder();
            var registry = new AutofacComponentRegistry(containerBuilder);

            registry.Register<IAzureStorageConfiguration, DefaultAzureStorageConfiguration>();
            registry.RegisterServiceBus();

            _bus = new AutofacComponentResolver(containerBuilder.Build()).Resolve<IServiceBus>().Start();
        }
    }
}

App.config #

Add an Application Configuration File item to create the App.config and populate as follows:

<?xml version="1.0" encoding="utf-8"?>

<configuration>
	<configSections>
		<section name="serviceBus" type="Shuttle.Esb.ServiceBusSection, Shuttle.Esb" />
		<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
	</configSections>

	<appSettings>
		<add key="azure" value="UseDevelopmentStorage=true;" />
	</appSettings>

	<log4net>
		<root>
			<level value="INFO" />
			<appender-ref ref="ConsoleAppender" />
			<appender-ref ref="RollingFileAppender" />
		</root>
		<appender name="ConsoleAppender" type="log4net.Appender.ColoredConsoleAppender">
			<layout type="log4net.Layout.PatternLayout">
				<conversionPattern value="%d [%t] %-5p %c - %m%n" />
			</layout>
		</appender>
		<appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
			<file value="logs\deferred-server" />
			<appendToFile value="true" />
			<rollingStyle value="Composite" />
			<maxSizeRollBackups value="10" />
			<maximumFileSize value="100000KB" />
			<datePattern value="-yyyyMMdd.'log'" />
			<param name="StaticLogFileName" value="false" />
			<layout type="log4net.Layout.PatternLayout">
				<conversionPattern value="%d [%t] %-5p %c - %m%n" />
			</layout>
		</appender>
	</log4net>

	<serviceBus>
		<inbox workQueueUri="azuremq://azure/shuttle-server-work" 
		       deferredQueueUri="azuremq://azure/shuttle-server-deferred"
		       errorQueueUri="azuremq://azure/shuttle-error" />
	</serviceBus>

</configuration>

RegisterMemberHandler #

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

using Shuttle.Core.Logging;
using Shuttle.Esb;
using Shuttle.Deferred.Messages;

namespace Shuttle.Deferred.Server
{
	public class RegisterMemberHandler : IMessageHandler<RegisterMemberCommand>
	{
	    private readonly ILog _log;

	    public RegisterMemberHandler()
	    {
	        _log = Log.For(this);
	    }

	    public void ProcessMessage(IHandlerContext<RegisterMemberCommand> context)
		{
		    _log.Information($"[MEMBER REGISTERED] : user name = '{context.Message.UserName}'");
		}
	}
}

This will use Log4Net to write out some information to the console window as well as a file.

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:

You have now implemented deferred message sending.

You will also notice that Log4Net has created the log file under ~\Shuttle.Deferred\Shuttle.Deferred.Server\bin\Debug\{framework}\logs.