ISSUE-1106 Add middleware examples

JustSaying.sln

@@ -75,6 +75,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "JustSaying.Extensions.Depen
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "JustSaying.Benchmark", "tests\JustSaying.Benchmark\JustSaying.Benchmark.csproj", "{83B43FC1-1F1C-4838-B67B-CE70D16870AF}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "JustSaying.Sample.Middleware", "samples\src\JustSaying.Sample.Middleware\JustSaying.Sample.Middleware.csproj", "{38DAC394-0A6E-4BB6-BCFC-8C21D2C64B3A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -133,6 +135,10 @@ Global
 		{83B43FC1-1F1C-4838-B67B-CE70D16870AF}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{83B43FC1-1F1C-4838-B67B-CE70D16870AF}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{83B43FC1-1F1C-4838-B67B-CE70D16870AF}.Release|Any CPU.Build.0 = Release|Any CPU
+		{38DAC394-0A6E-4BB6-BCFC-8C21D2C64B3A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{38DAC394-0A6E-4BB6-BCFC-8C21D2C64B3A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{38DAC394-0A6E-4BB6-BCFC-8C21D2C64B3A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{38DAC394-0A6E-4BB6-BCFC-8C21D2C64B3A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -155,6 +161,7 @@ Global
 		{A4D0E032-3AF1-437F-AF6B-4B602B8D4C49} = {77C93C37-DE5B-448F-9A23-6C9D0C8465CA}
 		{6AF4E086-6784-489C-9AB1-36F637A30094} = {E22A50F2-9952-4483-8AD1-09BE354FB3E4}
 		{83B43FC1-1F1C-4838-B67B-CE70D16870AF} = {E22A50F2-9952-4483-8AD1-09BE354FB3E4}
+		{38DAC394-0A6E-4BB6-BCFC-8C21D2C64B3A} = {77C93C37-DE5B-448F-9A23-6C9D0C8465CA}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {18FBDF85-C124-4444-9F03-D0D4F2B3A612}

samples/src/JustSaying.Sample.Middleware/Exceptions/BusinessException.cs

@@ -0,0 +1,6 @@
+namespace JustSaying.Sample.Middleware.Exceptions;
+
+public class BusinessException : Exception
+{
+    public string MessageId { get; set; }
+}

samples/src/JustSaying.Sample.Middleware/Extensions/ConfigurationExtensions.cs

@@ -0,0 +1,17 @@
+using Amazon;
+using Microsoft.Extensions.Configuration;
+
+namespace JustSaying.Sample.Middleware.Extensions;
+
+internal static class ConfigurationExtensions
+{
+    private const string AWSServiceUrlKey = "AWSServiceUrl";
+
+    private const string AWSRegionKey = "AWSRegion";
+
+    internal static bool HasAWSServiceUrl(this IConfiguration configuration) => !string.IsNullOrWhiteSpace(configuration[AWSServiceUrlKey]);
+
+    internal static Uri GetAWSServiceUri(this IConfiguration configuration) => new(configuration[AWSServiceUrlKey]);
+
+    internal static RegionEndpoint GetAWSRegion(this IConfiguration configuration) => RegionEndpoint.GetBySystemName(configuration[AWSRegionKey]);
+}

samples/src/JustSaying.Sample.Middleware/Handlers/SampleMessageHandler.cs

@@ -0,0 +1,16 @@
+using JustSaying.Messaging.MessageHandling;
+using JustSaying.Sample.Middleware.Messages;
+
+namespace JustSaying.Sample.Middleware.Handlers;
+
+/// <summary>
+/// A message handler that will always return true.
+/// </summary>
+public class SampleMessageHandler : IHandlerAsync<SampleMessage>
+{
+    public async Task<bool> Handle(SampleMessage message)
+    {
+        await Task.Delay(1000);
+        return true;
+    }
+}

samples/src/JustSaying.Sample.Middleware/Handlers/UnreliableMessageHandler.cs

@@ -0,0 +1,25 @@
+using JustSaying.Messaging.MessageHandling;
+using JustSaying.Sample.Middleware.Exceptions;
+using JustSaying.Sample.Middleware.Messages;
+using Serilog;
+
+namespace JustSaying.Sample.Middleware.Handlers;
+
+/// <summary>
+/// A message handler that will randomly throw an exception, mimicking a transient error.
+/// </summary>
+public class UnreliableMessageHandler : IHandlerAsync<UnreliableMessage>
+{
+    public async Task<bool> Handle(UnreliableMessage message)
+    {
+        await Task.Delay(1000);
+
+        if (Random.Shared.NextInt64() % 2 == 0)
+        {
+            Log.Information("Throwing for message id {MessageId}", message.Id);
+            throw new BusinessException() { MessageId = message.Id.ToString() };
+        }
+
+        return true;
+    }
+}

samples/src/JustSaying.Sample.Middleware/JustSaying.Sample.Middleware.csproj

@@ -0,0 +1,30 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\src\JustSaying.Extensions.DependencyInjection.Microsoft\JustSaying.Extensions.DependencyInjection.Microsoft.csproj" />
+    <ProjectReference Include="..\..\..\src\JustSaying.Models\JustSaying.Models.csproj" />
+    <ProjectReference Include="..\..\..\src\JustSaying\JustSaying.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="7.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="7.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.1" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="7.0.0" />
+    <PackageReference Include="Polly" Version="7.2.3" />
+    <PackageReference Include="Serilog.AspNetCore" Version="6.1.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="appsettings.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

samples/src/JustSaying.Sample.Middleware/JustSayingService.cs

@@ -0,0 +1,32 @@
+using JustSaying.Messaging;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace JustSaying.Sample.Middleware;
+
+/// <summary>
+/// A background service responsible for starting the JustSaying message bus and publisher.
+/// </summary>
+public class JustSayingService : IHostedService
+{
+    private readonly IMessagingBus _bus;
+    private readonly IMessagePublisher _publisher;
+    private readonly ILogger<JustSayingService> _logger;
+
+    public JustSayingService(IMessagingBus bus, IMessagePublisher publisher, ILogger<JustSayingService> logger)
+    {
+        _bus = bus;
+        _publisher = publisher;
+        _logger = logger;
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        await _bus.StartAsync(cancellationToken);
+        await _publisher.StartAsync(cancellationToken);
+
+        _logger.LogInformation("Message bus and publisher have started successfully");
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+}

samples/src/JustSaying.Sample.Middleware/Messages/SampleMessage.cs

@@ -0,0 +1,8 @@
+using JustSaying.Models;
+
+namespace JustSaying.Sample.Middleware.Messages;
+
+public class SampleMessage : Message
+{
+    public string SampleId { get; set; } = Guid.NewGuid().ToString();
+}

samples/src/JustSaying.Sample.Middleware/Messages/UnreliableMessage.cs

@@ -0,0 +1,8 @@
+using JustSaying.Models;
+
+namespace JustSaying.Sample.Middleware.Messages;
+
+public class UnreliableMessage : Message
+{
+    public string Name { get; set; } = Guid.NewGuid().ToString();
+}

samples/src/JustSaying.Sample.Middleware/Middlewares/EchoJustSayingMiddleware.cs

@@ -0,0 +1,31 @@
+using JustSaying.Messaging.Middleware;
+using Serilog;
+
+namespace JustSaying.Sample.Middleware.Middlewares;
+
+/// <summary>
+/// A middleware that will output a log message before and after a message has passed through it.
+/// </summary>
+public class EchoJustSayingMiddleware : MiddlewareBase<HandleMessageContext, bool>
+{
+    private readonly string _name;
+
+    public EchoJustSayingMiddleware(string name)
+    {
+        _name = name;
+    }
+
+    protected override async Task<bool> RunInnerAsync(HandleMessageContext context, Func<CancellationToken, Task<bool>> func, CancellationToken stoppingToken)
+    {
+        Log.Information("[{MiddlewareName}] Starting {Name} for {MessageType}", nameof(EchoJustSayingMiddleware), _name, context.Message.GetType().Name);
+
+        try
+        {
+            return await func(stoppingToken);
+        }
+        finally
+        {
+            Log.Information("[{MiddlewareName}] Ending {Name} for {MessageType}", nameof(EchoJustSayingMiddleware), _name, context.Message.GetType().Name);
+        }
+    }
+}

samples/src/JustSaying.Sample.Middleware/Middlewares/InterrogateMiddleware.cs

@@ -0,0 +1,25 @@
+using JustSaying.Messaging.Middleware;
+using JustSaying.Sample.Middleware.Messages;
+using Serilog;
+
+namespace JustSaying.Sample.Middleware.Middlewares;
+
+/// <summary>
+/// A middleware that will interrogate each message and output some information.
+/// </summary>
+public sealed class InterrogateMiddleware : MiddlewareBase<HandleMessageContext, bool>
+{
+    protected override async Task<bool> RunInnerAsync(HandleMessageContext context, Func<CancellationToken, Task<bool>> func, CancellationToken stoppingToken)
+    {
+        if (context.Message is SampleMessage simpleMessage)
+        {
+            Log.Information("[{MiddlewareName}] Hello SampleMessage! Your SampleId is {SampleId} and Id is {Id}", nameof(InterrogateMiddleware), simpleMessage.SampleId, simpleMessage.Id);
+        }
+        else if (context.Message is UnreliableMessage unreliableMessage)
+        {
+            Log.Information("[{MiddlewareName}] Hello UnreliableMessage! Hope you work this time....your Name is {Name} and Id is {Id}", nameof(InterrogateMiddleware),unreliableMessage.Name, context.Message.Id);
+        }
+
+        return await func(stoppingToken);
+    }
+}

samples/src/JustSaying.Sample.Middleware/Middlewares/PollyJustSayingMiddleware.cs

@@ -0,0 +1,40 @@
+using JustSaying.Messaging.Middleware;
+using JustSaying.Sample.Middleware.Exceptions;
+using Polly;
+using Serilog;
+
+namespace JustSaying.Sample.Middleware.Middlewares;
+
+/// <summary>
+/// A middleware that will wrap the handling of a message in the provided Polly policy.
+/// </summary>
+public class PollyJustSayingMiddleware : MiddlewareBase<HandleMessageContext, bool>
+{
+    private readonly AsyncPolicy _policy;
+
+    public PollyJustSayingMiddleware()
+    {
+        _policy = CreateMessageRetryPolicy();
+    }
+
+    protected override async Task<bool> RunInnerAsync(HandleMessageContext context, Func<CancellationToken, Task<bool>> func, CancellationToken stoppingToken)
+    {
+        Log.Information("[{MiddlewareName}] Started {MessageType}", nameof(PollyJustSayingMiddleware), context.Message.GetType().Name);
+
+        try
+        {
+            return await _policy.ExecuteAsync(() => func(stoppingToken));
+        }
+        finally
+        {
+            Log.Information("[{MiddlewareName}] Finished {MessageType}", nameof(PollyJustSayingMiddleware), context.Message.GetType().Name);
+        }
+    }
+
+    private static AsyncPolicy CreateMessageRetryPolicy()
+    {
+        return Policy.Handle<BusinessException>()
+            .WaitAndRetryAsync(3, count => TimeSpan.FromMilliseconds(Math.Max(count * 100, 1000)),
+                onRetry: (e, ts, retryCount, ctx) => Log.Information(e, "Retrying failed operation on count {RetryCount}", retryCount));
+    }
+}