├── .gitignore ├── LICENSE ├── README.md ├── SagasDemo.sln ├── src ├── Contracts │ ├── Configuration │ │ └── KafkaOptions.cs │ ├── Contracts.csproj │ ├── CustomerValidationRequestEvent.cs │ ├── CustomerValidationResponseEvent.cs │ ├── Exceptions │ │ └── NotATransientException.cs │ ├── FaultMessageEvent.cs │ ├── NotificationReply.cs │ ├── OrderRequestEvent.cs │ ├── OrderResponseEvent.cs │ ├── TaxesCalculationRequestEvent.cs │ └── TaxesCalculationResponseEvent.cs ├── CustomerValidationEngine │ ├── Consumers │ │ └── CustomerValidationConsumer.cs │ ├── CustomerValidationEngine.csproj │ ├── Extensions │ │ └── KafkaRegistrationExtensions.cs │ ├── Program.cs │ ├── Properties │ │ └── launchSettings.json │ └── appsettings.json ├── OrdersManagementApi │ ├── Controllers │ │ └── OrdersController.cs │ ├── Extensions │ │ └── KafkaRegistrationExtensions.cs │ ├── OrdersManagementApi.csproj │ ├── Program.cs │ ├── Properties │ │ └── launchSettings.json │ └── appsettings.json ├── OrdersOrchestrator │ ├── Extensions │ │ ├── KafkaRegistrationExtensions.cs │ │ └── SagasRepositoryRegistrationExtensions.cs │ ├── Middlewares │ │ ├── FaultProcessingMiddlewareFilter.cs │ │ └── SagaLoggingMiddlewareFilter.cs │ ├── OrdersOrchestrator.csproj │ ├── Program.cs │ ├── Properties │ │ └── launchSettings.json │ ├── Services │ │ ├── ApiService.cs │ │ └── IApiService.cs │ ├── StateMachines │ │ ├── CustomActivities │ │ │ ├── CustomerValidationActivity.cs │ │ │ ├── ProcessFaultActivity.cs │ │ │ ├── ReceiveOrderRequestActivity.cs │ │ │ └── TaxesCalculationActivity.cs │ │ ├── OrderRequestSagaDefinition.cs │ │ ├── OrderRequestSagaInstance.cs │ │ ├── OrderRequestStateMachine.cs │ │ └── OrderRequestStateMachineSupportExtensions.cs │ ├── Transports │ │ └── FaultTransport.cs │ └── appsettings.json └── TaxesCalculationEngine │ ├── Consumers │ └── TaxesCalculationConsumer.cs │ ├── Extensions │ └── KafkaRegistrationExtensions.cs │ ├── Program.cs │ ├── Properties │ └── launchSettings.json │ ├── TaxesCalculationEngine.csproj │ └── appsettings.json └── static ├── sagas-flow.drawio └── sagas-flow.png /.gitignore: -------------------------------------------------------------------------------- 1 | ## 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Kafka Sagas Demo 2 | 3 | ## Overview 4 | 5 | This was built as a POC to validate the usage of the Sagas pattern using some of the components provided by the Masstransit package. Here we tested some of the most basic Masstransit features related to the Sagas pattern implementation such as State Machines, State Machines Activities, Events Orchestration, Message Retry/Redelivery and Instance persistence to name a few. To develop this we used the [Masstransit documentation](https://masstransit.io/) and the [Kafka YouTube series](https://www.youtube.com/watch?v=CJ_srcJiIKs&list=PLx8uyNNs1ri0RJ3hqwcDze6yAkrmK1QI5 ) by Chris Patterson. 6 | 7 | ## Basic sagas flow 8 | 9 | Here we are presenting a basic flow of how all the components should work. We also implemented a fault recovery pipeline using an error topic. 10 | 11 | ![alt text](/static/sagas-flow.png) 12 | 13 | ## External servers 14 | 15 | To develop this application, we used some popular servers such as [Confluent Kafka Cloud](https://www.confluent.io/), [MongoDB Atlas](https://www.mongodb.com/atlas) and [Redis on Cloud](https://redis.com/). All the mentioned resources are very easy to use and have free trial plans. 16 | 17 | ## Usage 18 | 19 | Once you have the codebase, simply adjust the configuration files with your configuration and run all the projects. To produce messages to the Kafka server, use the `OrderManagentApi`. To facilitate, we are providing the topics list below so it will be easier to replicate it on your server. As far as database configuration, MassTransit makes it very easy, requiring minimal manual configuration. So, assuming you have your database server up and running, everything should work out of the box for both MongoDB and Redis. 20 | 21 | ### Topics list 22 | - ORDER_MANAGEMENT_SYSTEM.REQUEST 23 | - ORDER_MANAGEMENT_SYSTEM.RESPONSE 24 | - TAXES_CALCULATION_ENGINE.REQUEST 25 | - TAXES_CALCULATION_ENGINE.RESPONSE 26 | - CUSTOMER_VALIDATION_ENGINE.REQUEST 27 | - CUSTOMER_VALIDATION_ENGINE.RESPONSE 28 | - ERROR 29 | 30 | ## Important 31 | 32 | You can run database and Kafka servers locally. Just make sure to adjust all the configurations within all the runnable projects. 33 | If you're having a hard time trying to run this demo application, feel free to contact me and I will try to help the best way I can. -------------------------------------------------------------------------------- /SagasDemo.sln: -------------------------------------------------------------------------------- 1 |  2 | Microsoft Visual Studio Solution File, Format Version 12.00 3 | # Visual Studio Version 17 4 | VisualStudioVersion = 17.4.33110.190 5 | MinimumVisualStudioVersion = 10.0.40219.1 6 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "OrdersManagementApi", "src\OrdersManagementApi\OrdersManagementApi.csproj", "{A6EDEE5B-9D7C-4F93-8F7B-05F9FA90DACF}" 7 | EndProject 8 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "OrdersOrchestrator", "src\OrdersOrchestrator\OrdersOrchestrator.csproj", "{02C3961C-8C73-4607-9398-D4BAF7AE881D}" 9 | EndProject 10 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TaxesCalculationEngine", "src\TaxesCalculationEngine\TaxesCalculationEngine.csproj", "{901C6735-14DF-4067-AE6D-22D42E465BEB}" 11 | EndProject 12 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "CustomerValidationEngine", "src\CustomerValidationEngine\CustomerValidationEngine.csproj", "{259DFD73-14B2-4500-A614-1BDA4F0CC6CD}" 13 | EndProject 14 | Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Contracts", "src\Contracts\Contracts.csproj", "{525D8152-B5FE-498E-8A89-DA77D1E35714}" 15 | EndProject 16 | Global 17 | GlobalSection(SolutionConfigurationPlatforms) = preSolution 18 | Debug|Any CPU = Debug|Any CPU 19 | Release|Any CPU = Release|Any CPU 20 | EndGlobalSection 21 | GlobalSection(ProjectConfigurationPlatforms) = postSolution 22 | {A6EDEE5B-9D7C-4F93-8F7B-05F9FA90DACF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 23 | {A6EDEE5B-9D7C-4F93-8F7B-05F9FA90DACF}.Debug|Any CPU.Build.0 = Debug|Any CPU 24 | {A6EDEE5B-9D7C-4F93-8F7B-05F9FA90DACF}.Release|Any CPU.ActiveCfg = Release|Any CPU 25 | {A6EDEE5B-9D7C-4F93-8F7B-05F9FA90DACF}.Release|Any CPU.Build.0 = Release|Any CPU 26 | {02C3961C-8C73-4607-9398-D4BAF7AE881D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 27 | {02C3961C-8C73-4607-9398-D4BAF7AE881D}.Debug|Any CPU.Build.0 = Debug|Any CPU 28 | {02C3961C-8C73-4607-9398-D4BAF7AE881D}.Release|Any CPU.ActiveCfg = Release|Any CPU 29 | {02C3961C-8C73-4607-9398-D4BAF7AE881D}.Release|Any CPU.Build.0 = Release|Any CPU 30 | {901C6735-14DF-4067-AE6D-22D42E465BEB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 31 | {901C6735-14DF-4067-AE6D-22D42E465BEB}.Debug|Any CPU.Build.0 = Debug|Any CPU 32 | {901C6735-14DF-4067-AE6D-22D42E465BEB}.Release|Any CPU.ActiveCfg = Release|Any CPU 33 | {901C6735-14DF-4067-AE6D-22D42E465BEB}.Release|Any CPU.Build.0 = Release|Any CPU 34 | {259DFD73-14B2-4500-A614-1BDA4F0CC6CD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 35 | {259DFD73-14B2-4500-A614-1BDA4F0CC6CD}.Debug|Any CPU.Build.0 = Debug|Any CPU 36 | {259DFD73-14B2-4500-A614-1BDA4F0CC6CD}.Release|Any CPU.ActiveCfg = Release|Any CPU 37 | {259DFD73-14B2-4500-A614-1BDA4F0CC6CD}.Release|Any CPU.Build.0 = Release|Any CPU 38 | {525D8152-B5FE-498E-8A89-DA77D1E35714}.Debug|Any CPU.ActiveCfg = Debug|Any CPU 39 | {525D8152-B5FE-498E-8A89-DA77D1E35714}.Debug|Any CPU.Build.0 = Debug|Any CPU 40 | {525D8152-B5FE-498E-8A89-DA77D1E35714}.Release|Any CPU.ActiveCfg = Release|Any CPU 41 | {525D8152-B5FE-498E-8A89-DA77D1E35714}.Release|Any CPU.Build.0 = Release|Any CPU 42 | EndGlobalSection 43 | GlobalSection(SolutionProperties) = preSolution 44 | HideSolutionNode = FALSE 45 | EndGlobalSection 46 | GlobalSection(ExtensibilityGlobals) = postSolution 47 | SolutionGuid = {3CDE34AD-0937-420D-8A56-F3D50AAFBCEA} 48 | EndGlobalSection 49 | EndGlobal 50 | -------------------------------------------------------------------------------- /src/Contracts/Configuration/KafkaOptions.cs: -------------------------------------------------------------------------------- 1 | using Confluent.Kafka; 2 | using StackExchange.Redis; 3 | 4 | namespace Contracts.Configuration; 5 | 6 | public sealed record KafkaOptions 7 | { 8 | public string ConsumerGroup { get; set; } = default!; 9 | public Topics Topics { get; set; } = default!; 10 | public ClientConfig ClientConfig { get; set; } = default!; 11 | public MongoDb MongoDb { get; set; } = default!; 12 | public RedisDb RedisDb { get; set; } = default!; 13 | }; 14 | 15 | public sealed record Topics 16 | { 17 | public string OrderManagementSystemRequest { get; set; } = default!; 18 | public string OrderManagementSystemResponse { get; set; } = default!; 19 | public string TaxesCalculationEngineRequest { get; set; } = default!; 20 | public string TaxesCalculationEngineResponse { get; set; } = default!; 21 | public string CustomerValidationEngineRequest { get; set; } = default!; 22 | public string CustomerValidationEngineResponse { get; set; } = default!; 23 | public string Error { get; set; } = default!; 24 | } 25 | 26 | public sealed record MongoDb 27 | { 28 | public string ConnectionString { get; set; } = default!; 29 | public string DatabaseName { get; set; } = default!; 30 | public string CollectionName { get; set; } = default!; 31 | } 32 | 33 | public sealed record RedisDb 34 | { 35 | public string Endpoint { get; set; } = default!; 36 | public string Password { get; set; } = default!; 37 | public string KeyPrefix { get; set; } = default!; 38 | } -------------------------------------------------------------------------------- /src/Contracts/Contracts.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | net6.0 5 | enable 6 | enable 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | -------------------------------------------------------------------------------- /src/Contracts/CustomerValidationRequestEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record CustomerValidationRequestEvent 4 | { 5 | public string CustomerId { get; set; } = string.Empty; 6 | } 7 | 8 | -------------------------------------------------------------------------------- /src/Contracts/CustomerValidationResponseEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record CustomerValidationResponseEvent 4 | { 5 | public string CustomerType { get; set; } = default!; 6 | } 7 | 8 | -------------------------------------------------------------------------------- /src/Contracts/Exceptions/NotATransientException.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts.Exceptions; 2 | 3 | [Serializable] 4 | public class NotATransientException : Exception 5 | { 6 | public NotATransientException() { } 7 | 8 | public NotATransientException(string message) 9 | : base(message) { } 10 | 11 | public NotATransientException(string message, Exception inner) 12 | : base(message, inner) { } 13 | } -------------------------------------------------------------------------------- /src/Contracts/FaultMessageEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record FaultMessageEvent 4 | { 5 | public object? Event { get; set; } = default!; 6 | public string? ExceptionMessage { get; set; } 7 | } -------------------------------------------------------------------------------- /src/Contracts/NotificationReply.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts 2 | { 3 | public sealed class NotificationReply 4 | where TMessage: class 5 | { 6 | public bool Success { get; set; } 7 | public string? Reason { get; set; } 8 | public TMessage? Data { get; set; } 9 | } 10 | } 11 | -------------------------------------------------------------------------------- /src/Contracts/OrderRequestEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record OrderRequestEvent 4 | { 5 | public string CustomerId { get; set;} = default!; 6 | public string ItemId { get; set; } = default!; 7 | } -------------------------------------------------------------------------------- /src/Contracts/OrderResponseEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record OrderResponseEvent 4 | { 5 | public string CustomerId { get; set; } = default!; 6 | public string CustomerType { get; set; } = default!; 7 | public TaxesCalculationResponseEvent TaxesCalculation { get; set; } = default!; 8 | } -------------------------------------------------------------------------------- /src/Contracts/TaxesCalculationRequestEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record TaxesCalculationRequestEvent 4 | { 5 | public string CustomerType { get; set; } = default!; 6 | public string ItemId { get; set; } = default!; 7 | } -------------------------------------------------------------------------------- /src/Contracts/TaxesCalculationResponseEvent.cs: -------------------------------------------------------------------------------- 1 | namespace Contracts; 2 | 3 | public record TaxesCalculationResponseEvent 4 | { 5 | public string ItemId { get; set; } = default!; 6 | public decimal TaxAAA { get; set; } 7 | public decimal TaxBBB { get; set; } 8 | public decimal TaxCCC { get; set; } 9 | } -------------------------------------------------------------------------------- /src/CustomerValidationEngine/Consumers/CustomerValidationConsumer.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | 4 | namespace CustomerValidationEngine.Consumers; 5 | 6 | public sealed class CustomerValidationConsumer : IConsumer 7 | { 8 | private readonly ITopicProducer producer; 9 | 10 | public CustomerValidationConsumer(ITopicProducer producer) 11 | { 12 | this.producer = producer; 13 | } 14 | 15 | async Task IConsumer 16 | .Consume(ConsumeContext context) 17 | { 18 | ArgumentNullException.ThrowIfNull(context, nameof(context)); 19 | 20 | var key = Guid.NewGuid(); 21 | 22 | var response = new CustomerValidationResponseEvent 23 | { 24 | CustomerType = GenerateCustomerType(), 25 | }; 26 | 27 | await producer 28 | .Produce(key.ToString(), response) 29 | .ConfigureAwait(false); 30 | } 31 | 32 | private static string GenerateCustomerType() 33 | { 34 | return new Random().Next(1, 5) switch 35 | { 36 | 1 => "Regular", 37 | 2 => "Premium", 38 | 3 => "Super Premium", 39 | _ => "Unknown" 40 | }; 41 | } 42 | } -------------------------------------------------------------------------------- /src/CustomerValidationEngine/CustomerValidationEngine.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | net6.0 5 | enable 6 | enable 7 | fc155dc0-4ca0-483e-89f9-75a60c8746e7 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | -------------------------------------------------------------------------------- /src/CustomerValidationEngine/Extensions/KafkaRegistrationExtensions.cs: -------------------------------------------------------------------------------- 1 | using Confluent.Kafka; 2 | using Contracts; 3 | using Contracts.Configuration; 4 | using CustomerValidationEngine.Consumers; 5 | using MassTransit; 6 | 7 | namespace CustomerValidationEngine.Extensions; 8 | 9 | public static class KafkaRegistrationExtensions 10 | { 11 | internal static IServiceCollection AddCustomKafka(this IServiceCollection services, IConfiguration configuration) 12 | { 13 | ArgumentNullException.ThrowIfNull(services, nameof(services)); 14 | ArgumentNullException.ThrowIfNull(configuration, nameof(configuration)); 15 | 16 | var kafkaOptions = configuration 17 | .GetSection("KafkaOptions") 18 | .Get(); 19 | 20 | services.AddMassTransit(massTransit => 21 | { 22 | massTransit.UsingInMemory((context, cfg) => 23 | { 24 | cfg.ConfigureEndpoints(context); 25 | }); 26 | 27 | massTransit.AddRider(rider => 28 | { 29 | rider.AddProducer(kafkaOptions.Topics.CustomerValidationEngineResponse); 30 | rider.AddConsumersFromNamespaceContaining(); 31 | 32 | rider.UsingKafka(kafkaOptions.ClientConfig, (riderContext, kafkaConfig) => 33 | { 34 | kafkaConfig.TopicEndpoint( 35 | topicName: kafkaOptions.Topics.CustomerValidationEngineRequest, 36 | groupId: kafkaOptions.ConsumerGroup, 37 | configure: topicConfig => 38 | { 39 | topicConfig.AutoOffsetReset = AutoOffsetReset.Earliest; 40 | topicConfig.ConfigureConsumer(riderContext); 41 | topicConfig.DiscardSkippedMessages(); 42 | }); 43 | }); 44 | }); 45 | }); 46 | 47 | return services; 48 | } 49 | } 50 | 51 | -------------------------------------------------------------------------------- /src/CustomerValidationEngine/Program.cs: -------------------------------------------------------------------------------- 1 | using CustomerValidationEngine.Extensions; 2 | 3 | var builder = WebApplication.CreateBuilder(args); 4 | 5 | builder.Services.AddCustomKafka(builder.Configuration); 6 | builder.Services.AddControllers(); 7 | builder.Services.AddHealthChecks(); 8 | 9 | var app = builder.Build(); 10 | 11 | app.UseRouting(); 12 | app.UseHttpsRedirection(); 13 | app.UseAuthorization(); 14 | app.MapControllers(); 15 | app.Run(); -------------------------------------------------------------------------------- /src/CustomerValidationEngine/Properties/launchSettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "profiles": { 3 | "CustomerValidationEngine": { 4 | "commandName": "Project", 5 | "dotnetRunMessages": true, 6 | "applicationUrl": "https://localhost:7099;http://localhost:5198", 7 | "environmentVariables": { 8 | "DOTNET_ENVIRONMENT": "Development" 9 | } 10 | } 11 | } 12 | } 13 | -------------------------------------------------------------------------------- /src/CustomerValidationEngine/appsettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "Logging": { 3 | "LogLevel": { 4 | "Default": "Information", 5 | "Microsoft.AspNetCore": "Warning" 6 | } 7 | }, 8 | "KafkaOptions": { 9 | "ConsumerGroup": "CustomerValidationEngine.Group", 10 | "Topics": { 11 | "CustomerValidationEngineRequest": "CUSTOMER_VALIDATION_ENGINE.REQUEST", 12 | "CustomerValidationEngineResponse": "CUSTOMER_VALIDATION_ENGINE.RESPONSE" 13 | }, 14 | "ClientConfig": { 15 | "BootstrapServers": "pkc-6ojv2.us-west4.gcp.confluent.cloud:9092", 16 | "SaslMechanism": "PLAIN", 17 | "SecurityProtocol": "SASLSSL", 18 | "SaslUsername": "", 19 | "SaslPassword": "" 20 | } 21 | } 22 | } 23 | -------------------------------------------------------------------------------- /src/OrdersManagementApi/Controllers/OrdersController.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | using Microsoft.AspNetCore.Mvc; 4 | 5 | namespace OrdersManagementApi.Controllers; 6 | 7 | [ApiController] 8 | [Route("[controller]")] 9 | public sealed class OrdersController : ControllerBase 10 | { 11 | private readonly ITopicProducer _producer; 12 | 13 | public OrdersController(ITopicProducer producer) 14 | { 15 | _producer = producer; 16 | } 17 | 18 | [HttpPost(Name = "Place")] 19 | public async Task Post([FromBody] OrderRequestEvent orderRequest) 20 | { 21 | var key = Guid.NewGuid(); 22 | var correlationId = Guid.NewGuid(); 23 | 24 | await _producer 25 | .Produce( 26 | key.ToString(), 27 | orderRequest, 28 | Pipe.Execute(p => 29 | { 30 | p.CorrelationId = correlationId; 31 | })) 32 | .ConfigureAwait(false); 33 | 34 | return Accepted(new 35 | { 36 | CorrelationId = correlationId, 37 | Key = key 38 | }); 39 | } 40 | } -------------------------------------------------------------------------------- /src/OrdersManagementApi/Extensions/KafkaRegistrationExtensions.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using Contracts.Configuration; 3 | using MassTransit; 4 | 5 | namespace OrdersManagementApi.Extensions; 6 | 7 | internal static class KafkaExtensions 8 | { 9 | internal static IServiceCollection AddCustomKafka( 10 | this IServiceCollection services, 11 | IConfiguration configuration) 12 | { 13 | ArgumentNullException.ThrowIfNull(services, nameof(services)); 14 | ArgumentNullException.ThrowIfNull(configuration, nameof(configuration)); 15 | 16 | var kafkaOptions = configuration 17 | .GetSection("KafkaOptions") 18 | .Get(); 19 | 20 | services.AddMassTransit(configureMassTransit => 21 | { 22 | configureMassTransit.UsingInMemory(); 23 | configureMassTransit.AddRider(configureRider => 24 | { 25 | configureRider.AddProducer(kafkaOptions.Topics.OrderManagementSystemRequest); 26 | configureRider.UsingKafka(kafkaOptions.ClientConfig, (_, _) => { }); 27 | }); 28 | }); 29 | 30 | return services; 31 | } 32 | } -------------------------------------------------------------------------------- /src/OrdersManagementApi/OrdersManagementApi.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | net6.0 5 | enable 6 | enable 7 | 1e06faf2-09fe-4eaa-a398-709448408328 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | -------------------------------------------------------------------------------- /src/OrdersManagementApi/Program.cs: -------------------------------------------------------------------------------- 1 | using OrdersManagementApi.Extensions; 2 | 3 | var builder = WebApplication.CreateBuilder(args); 4 | 5 | // Add services to the container. 6 | builder.Services.AddControllers(); 7 | 8 | // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle 9 | builder.Services.AddEndpointsApiExplorer(); 10 | builder.Services.AddSwaggerGen(); 11 | builder.Services.AddCustomKafka(builder.Configuration); 12 | 13 | var app = builder.Build(); 14 | 15 | // Configure the HTTP request pipeline. 16 | if (app.Environment.IsDevelopment()) 17 | { 18 | app.UseSwagger(); 19 | app.UseSwaggerUI(); 20 | } 21 | 22 | app.UseHttpsRedirection(); 23 | app.UseAuthorization(); 24 | app.MapControllers(); 25 | app.Run();; -------------------------------------------------------------------------------- /src/OrdersManagementApi/Properties/launchSettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "$schema": "https://json.schemastore.org/launchsettings.json", 3 | "profiles": { 4 | "Producer": { 5 | "commandName": "Project", 6 | "dotnetRunMessages": true, 7 | "launchBrowser": true, 8 | "launchUrl": "swagger", 9 | "applicationUrl": "https://localhost:7059;http://localhost:5167", 10 | "environmentVariables": { 11 | "ASPNETCORE_ENVIRONMENT": "Development" 12 | } 13 | } 14 | } 15 | } 16 | -------------------------------------------------------------------------------- /src/OrdersManagementApi/appsettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "Logging": { 3 | "LogLevel": { 4 | "Default": "Information", 5 | "Microsoft.AspNetCore": "Warning" 6 | } 7 | }, 8 | "KafkaOptions": { 9 | "Topics": { 10 | "OrderManagementSystemRequest": "ORDER_MANAGEMENT_SYSTEM.REQUEST" 11 | }, 12 | "ClientConfig": { 13 | "BootstrapServers": "pkc-6ojv2.us-west4.gcp.confluent.cloud:9092", 14 | "SaslMechanism": "PLAIN", 15 | "SecurityProtocol": "SASLSSL", 16 | "SaslUsername": "", 17 | "SaslPassword": "" 18 | } 19 | }, 20 | "AllowedHosts": "*" 21 | } 22 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Extensions/KafkaRegistrationExtensions.cs: -------------------------------------------------------------------------------- 1 | using Confluent.Kafka; 2 | using Contracts; 3 | using Contracts.Configuration; 4 | using MassTransit; 5 | using MassTransit.Transports; 6 | using OrdersOrchestrator.StateMachines; 7 | using OrdersOrchestrator.Transports; 8 | 9 | namespace OrdersOrchestrator.Extensions; 10 | 11 | internal static class KafkaRegistrationExtensions 12 | { 13 | internal static IServiceCollection AddCustomKafka(this IServiceCollection services, IConfiguration configuration) 14 | { 15 | ArgumentNullException.ThrowIfNull(services, nameof(services)); 16 | ArgumentNullException.ThrowIfNull(configuration, nameof(configuration)); 17 | 18 | var kafkaOptions = configuration 19 | .GetSection(nameof(KafkaOptions)) 20 | .Get(); 21 | 22 | services.AddMassTransit(massTransit => 23 | { 24 | massTransit.UsingInMemory((context, cfg) => cfg.ConfigureEndpoints(context)); 25 | massTransit.AddRider(rider => 26 | { 27 | rider.AddTransient(); 28 | 29 | rider 30 | .AddSagaStateMachine(typeof(OrderRequestSagaDefinition)) 31 | .ConfigureMongoRepository(kafkaOptions.MongoDb); 32 | 33 | rider.AddProducer>(kafkaOptions.Topics.OrderManagementSystemResponse); 34 | rider.AddProducer(kafkaOptions.Topics.TaxesCalculationEngineRequest); 35 | rider.AddProducer(kafkaOptions.Topics.CustomerValidationEngineRequest); 36 | rider.AddProducer(kafkaOptions.Topics.Error); 37 | rider.AddProducer(kafkaOptions.Topics.OrderManagementSystemRequest); 38 | 39 | rider.UsingKafka(kafkaOptions.ClientConfig, (riderContext, kafkaConfig) => 40 | { 41 | kafkaConfig.TopicEndpoint( 42 | topicName: kafkaOptions.Topics.OrderManagementSystemRequest, 43 | groupId: kafkaOptions.ConsumerGroup, 44 | configure: topicConfig => 45 | { 46 | topicConfig.AutoOffsetReset = AutoOffsetReset.Earliest; 47 | topicConfig.DiscardSkippedMessages(); 48 | topicConfig.ConfigureSaga(riderContext); 49 | topicConfig.UseInMemoryOutbox(riderContext); 50 | }); 51 | 52 | kafkaConfig.TopicEndpoint( 53 | topicName: kafkaOptions.Topics.TaxesCalculationEngineResponse, 54 | groupId: kafkaOptions.ConsumerGroup, 55 | configure: topicConfig => 56 | { 57 | topicConfig.AutoOffsetReset = AutoOffsetReset.Earliest; 58 | topicConfig.DiscardSkippedMessages(); 59 | topicConfig.ConfigureSaga(riderContext); 60 | topicConfig.UseInMemoryOutbox(riderContext); 61 | }); 62 | 63 | kafkaConfig.TopicEndpoint( 64 | topicName: kafkaOptions.Topics.CustomerValidationEngineResponse, 65 | groupId: kafkaOptions.ConsumerGroup, 66 | configure: topicConfig => 67 | { 68 | topicConfig.AutoOffsetReset = AutoOffsetReset.Earliest; 69 | topicConfig.DiscardSkippedMessages(); 70 | topicConfig.ConfigureSaga(riderContext); 71 | topicConfig.UseInMemoryOutbox(riderContext); 72 | }); 73 | 74 | kafkaConfig.TopicEndpoint( 75 | topicName: kafkaOptions.Topics.Error, 76 | groupId: kafkaOptions.Topics.Error, 77 | configure: topicConfig => 78 | { 79 | topicConfig.AutoOffsetReset = AutoOffsetReset.Earliest; 80 | topicConfig.DiscardSkippedMessages(); 81 | topicConfig.ConfigureSaga(riderContext); 82 | topicConfig.UseInMemoryOutbox(riderContext); 83 | 84 | }); 85 | }); 86 | }); 87 | }); 88 | 89 | return services; 90 | } 91 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Extensions/SagasRepositoryRegistrationExtensions.cs: -------------------------------------------------------------------------------- 1 | using Contracts.Configuration; 2 | using MassTransit; 3 | using StackExchange.Redis; 4 | 5 | namespace OrdersOrchestrator.Extensions; 6 | 7 | internal static class SagasRepositoryRegistrationExtensions 8 | { 9 | internal static ISagaRegistrationConfigurator ConfigureRedisRepository( 10 | this ISagaRegistrationConfigurator configurator, 11 | RedisDb redisOptions) 12 | where TStateMachine : class, SagaStateMachine 13 | where T : class, SagaStateMachineInstance, ISagaVersion 14 | { 15 | ArgumentNullException.ThrowIfNull(configurator, nameof(configurator)); 16 | ArgumentNullException.ThrowIfNull(redisOptions, nameof(redisOptions)); 17 | 18 | return configurator.RedisRepository(configure => 19 | { 20 | var options = new ConfigurationOptions 21 | { 22 | EndPoints = { redisOptions.Endpoint }, 23 | Password = redisOptions.Password 24 | }; 25 | 26 | configure.ConcurrencyMode = ConcurrencyMode.Pessimistic; 27 | configure.KeyPrefix = redisOptions.KeyPrefix; 28 | configure.DatabaseConfiguration(options); 29 | }); 30 | } 31 | 32 | internal static ISagaRegistrationConfigurator ConfigureMongoRepository( 33 | this ISagaRegistrationConfigurator configurator, 34 | MongoDb mongoDb) 35 | where TStateMachine : class, SagaStateMachine 36 | where T : class, SagaStateMachineInstance, ISagaVersion 37 | { 38 | ArgumentNullException.ThrowIfNull(configurator, nameof(configurator)); 39 | ArgumentNullException.ThrowIfNull(mongoDb, nameof(mongoDb)); 40 | 41 | return configurator.MongoDbRepository(configure => 42 | { 43 | configure.CollectionName = mongoDb.CollectionName; 44 | configure.Connection = mongoDb.ConnectionString; 45 | configure.DatabaseName = mongoDb.DatabaseName; 46 | }); 47 | } 48 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Middlewares/FaultProcessingMiddlewareFilter.cs: -------------------------------------------------------------------------------- 1 | using MassTransit; 2 | using MassTransit.Transports; 3 | 4 | namespace OrdersOrchestrator.Middlewares; 5 | 6 | public sealed class FaultProcessingMiddlewareFilter 7 | : IFilter 8 | { 9 | private readonly IErrorTransport errorTransport; 10 | 11 | public FaultProcessingMiddlewareFilter(IErrorTransport errorTransport) 12 | { 13 | this.errorTransport = errorTransport; 14 | } 15 | 16 | async Task IFilter 17 | .Send(ExceptionReceiveContext context, IPipe next) 18 | { 19 | ArgumentNullException.ThrowIfNull(context, nameof(context)); 20 | ArgumentNullException.ThrowIfNull(next, nameof(next)); 21 | 22 | context.AddOrUpdatePayload( 23 | () => errorTransport, 24 | _ => errorTransport); 25 | 26 | await next.Send(context) 27 | .ConfigureAwait(false); 28 | } 29 | 30 | void IProbeSite.Probe(ProbeContext context) 31 | => context.CreateScope(nameof(FaultProcessingMiddlewareFilter)); 32 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Middlewares/SagaLoggingMiddlewareFilter.cs: -------------------------------------------------------------------------------- 1 | using MassTransit; 2 | 3 | namespace OrdersOrchestrator.Middlewares; 4 | 5 | public sealed class SagaLoggingMiddlewareFilter 6 | : IFilter> 7 | where TSaga : class, ISaga 8 | { 9 | async Task IFilter>.Send( 10 | SagaConsumeContext context, 11 | IPipe> next) 12 | { 13 | ArgumentNullException.ThrowIfNull(context, nameof(context)); 14 | ArgumentNullException.ThrowIfNull(next, nameof(next)); 15 | 16 | await next 17 | .Send(context) 18 | .ConfigureAwait(false); 19 | } 20 | 21 | void IProbeSite.Probe(ProbeContext context) 22 | => context.CreateScope(nameof(SagaLoggingMiddlewareFilter)); 23 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/OrdersOrchestrator.csproj: -------------------------------------------------------------------------------- 1 |  2 | 3 | 4 | net6.0 5 | enable 6 | enable 7 | dotnet-Orchestrator-ACC8B0E7-C79B-46D3-85F9-30223993442F 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | all 20 | runtime; build; native; contentfiles; analyzers; buildtransitive 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Program.cs: -------------------------------------------------------------------------------- 1 | using OrdersOrchestrator.Extensions; 2 | using OrdersOrchestrator.Services; 3 | 4 | var builder = WebApplication.CreateBuilder(args); 5 | 6 | builder.Services.AddCustomKafka(builder.Configuration); 7 | builder.Services.AddControllers(); 8 | builder.Services.AddHealthChecks(); 9 | builder.Services.AddTransient(); 10 | 11 | var app = builder.Build(); 12 | 13 | app.UseRouting(); 14 | app.UseHttpsRedirection(); 15 | app.UseAuthorization(); 16 | app.MapControllers(); 17 | app.Run(); -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Properties/launchSettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "profiles": { 3 | "Orchestrator": { 4 | "commandName": "Project", 5 | "dotnetRunMessages": true, 6 | "applicationUrl": "https://localhost:7079;http://localhost:5187", 7 | "environmentVariables": { 8 | "ASPNETCORE_ENVIRONMENT": "Development" 9 | } 10 | } 11 | } 12 | } 13 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Services/ApiService.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | 3 | namespace OrdersOrchestrator.Services 4 | { 5 | public sealed class ApiService : IApiService 6 | { 7 | public Task ValidateIncomingOrderRequestAsync(OrderRequestEvent @event) 8 | => Task.FromResult(@event.CustomerId!.ToUpper() == "ERROR"); 9 | 10 | 11 | public Task ValidateIncomingCustomerValidationResult(CustomerValidationResponseEvent @event) 12 | => Task.FromResult(@event.CustomerType == "Unknown"); 13 | 14 | 15 | public Task ValidateIncomingTaxesCalculationResult(TaxesCalculationResponseEvent @event) 16 | => Task.FromResult(@event.ItemId!.ToUpper() == "ERROR"); 17 | } 18 | } 19 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Services/IApiService.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | 3 | namespace OrdersOrchestrator.Services 4 | { 5 | public interface IApiService 6 | { 7 | Task ValidateIncomingOrderRequestAsync(OrderRequestEvent @event); 8 | Task ValidateIncomingCustomerValidationResult(CustomerValidationResponseEvent @event); 9 | Task ValidateIncomingTaxesCalculationResult(TaxesCalculationResponseEvent @event); 10 | } 11 | } 12 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/CustomActivities/CustomerValidationActivity.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using Contracts.Exceptions; 3 | using MassTransit; 4 | using OrdersOrchestrator.Services; 5 | 6 | namespace OrdersOrchestrator.StateMachines.CustomActivities; 7 | 8 | public sealed class CustomerValidationActivity 9 | : IStateMachineActivity 10 | { 11 | private readonly ITopicProducer taxesCalculationEngineProducer; 12 | private readonly IApiService apiService; 13 | 14 | public CustomerValidationActivity( 15 | ITopicProducer taxesCalculationEngineProducer, 16 | IApiService apiService) 17 | { 18 | this.taxesCalculationEngineProducer = taxesCalculationEngineProducer; 19 | this.apiService = apiService; 20 | } 21 | 22 | async Task IStateMachineActivity.Execute( 23 | BehaviorContext context, 24 | IBehavior next) 25 | { 26 | if (await apiService.ValidateIncomingCustomerValidationResult(context.Message)) 27 | { 28 | throw new NotATransientException("Error during the customer validation!"); 29 | } 30 | 31 | var taxesCalculationRequestEvent = new TaxesCalculationRequestEvent 32 | { 33 | ItemId = context.Saga.ItemId!, 34 | CustomerType = context.Message.CustomerType 35 | }; 36 | 37 | await taxesCalculationEngineProducer 38 | .Produce( 39 | Guid.NewGuid().ToString(), 40 | taxesCalculationRequestEvent, 41 | context.CancellationToken) 42 | .ConfigureAwait(false); 43 | 44 | await next 45 | .Execute(context) 46 | .ConfigureAwait(false); 47 | } 48 | 49 | async Task IStateMachineActivity.Faulted( 50 | BehaviorExceptionContext context, 51 | IBehavior next) 52 | => await next.Faulted(context).ConfigureAwait(false); 53 | 54 | void IProbeSite.Probe(ProbeContext context) => context.CreateScope(nameof(CustomerValidationActivity)); 55 | void IVisitable.Accept(StateMachineVisitor visitor) => visitor.Visit(this); 56 | } 57 | 58 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/CustomActivities/ProcessFaultActivity.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | 4 | namespace OrdersOrchestrator.StateMachines.CustomActivities; 5 | 6 | public sealed class ProcessFaultActivity 7 | : IStateMachineActivity 8 | { 9 | async Task IStateMachineActivity.Execute( 10 | BehaviorContext context, 11 | IBehavior next) 12 | { 13 | context.Saga.NotificationReply = new NotificationReply() 14 | { 15 | Reason = context.Message.ExceptionMessage 16 | }; 17 | 18 | await next 19 | .Execute(context) 20 | .ConfigureAwait(false); 21 | } 22 | 23 | async Task IStateMachineActivity.Faulted( 24 | BehaviorExceptionContext context, 25 | IBehavior next) 26 | => await next.Faulted(context).ConfigureAwait(false); 27 | 28 | void IProbeSite.Probe(ProbeContext context) => context.CreateScope(nameof(ProcessFaultActivity)); 29 | void IVisitable.Accept(StateMachineVisitor visitor) => visitor.Visit(this); 30 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/CustomActivities/ReceiveOrderRequestActivity.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using Contracts.Exceptions; 3 | using MassTransit; 4 | using OrdersOrchestrator.Services; 5 | 6 | namespace OrdersOrchestrator.StateMachines.CustomActivities; 7 | 8 | public sealed class ReceiveOrderRequestActivity 9 | : IStateMachineActivity 10 | { 11 | private readonly IApiService apiService; 12 | private readonly ITopicProducer customerValidationEngineProducer; 13 | 14 | public ReceiveOrderRequestActivity( 15 | IApiService apiService, 16 | ITopicProducer customerValidationEngineProducer) 17 | { 18 | this.apiService = apiService; 19 | this.customerValidationEngineProducer = customerValidationEngineProducer; 20 | } 21 | 22 | async Task IStateMachineActivity.Execute( 23 | BehaviorContext context, 24 | IBehavior next) 25 | { 26 | // Some dummy validation to test the error handling flow 27 | if (await apiService 28 | .ValidateIncomingOrderRequestAsync(context.Message) 29 | .ConfigureAwait(false)) 30 | { 31 | throw new NotATransientException("Error during order request validation!"); 32 | } 33 | 34 | var customerValidationEvent = new 35 | { 36 | context.Message.CustomerId, 37 | }; 38 | 39 | await customerValidationEngineProducer 40 | .Produce( 41 | Guid.NewGuid().ToString(), 42 | customerValidationEvent, 43 | context.CancellationToken) 44 | .ConfigureAwait(false); 45 | 46 | await next.Execute(context) 47 | .ConfigureAwait(false); 48 | } 49 | 50 | async Task IStateMachineActivity.Faulted( 51 | BehaviorExceptionContext context, 52 | IBehavior next) 53 | => await next.Faulted(context).ConfigureAwait(false); 54 | 55 | void IProbeSite.Probe(ProbeContext context) => context.CreateScope(nameof(ReceiveOrderRequestActivity)); 56 | void IVisitable.Accept(StateMachineVisitor visitor) => visitor.Visit(this); 57 | 58 | } 59 | 60 | -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/CustomActivities/TaxesCalculationActivity.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using Contracts.Exceptions; 3 | using MassTransit; 4 | using OrdersOrchestrator.Services; 5 | 6 | namespace OrdersOrchestrator.StateMachines.CustomActivities; 7 | 8 | public sealed class TaxesCalculationActivity 9 | : IStateMachineActivity 10 | { 11 | private readonly IApiService apiService; 12 | 13 | public TaxesCalculationActivity( 14 | IApiService apiService) 15 | { 16 | this.apiService = apiService; 17 | } 18 | 19 | async Task IStateMachineActivity.Execute( 20 | BehaviorContext context, 21 | IBehavior next) 22 | { 23 | if (await apiService.ValidateIncomingTaxesCalculationResult(context.Message)) 24 | { 25 | throw new NotATransientException("Error during order request validation!"); 26 | } 27 | 28 | context.Saga.NotificationReply = new NotificationReply 29 | { 30 | Success = true, 31 | Data = new OrderResponseEvent 32 | { 33 | CustomerId = context.Saga.CustomerId!, 34 | CustomerType = context.Saga.CustomerType!, 35 | TaxesCalculation = context.Message, 36 | } 37 | }; 38 | 39 | await next 40 | .Execute(context) 41 | .ConfigureAwait(false); 42 | } 43 | 44 | async Task IStateMachineActivity.Faulted( 45 | BehaviorExceptionContext context, 46 | IBehavior next) 47 | => await next.Faulted(context).ConfigureAwait(false); 48 | 49 | void IProbeSite.Probe(ProbeContext context) => context.CreateScope(nameof(ReceiveOrderRequestActivity)); 50 | void IVisitable.Accept(StateMachineVisitor visitor) => visitor.Visit(this); 51 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/OrderRequestSagaDefinition.cs: -------------------------------------------------------------------------------- 1 | using Contracts.Exceptions; 2 | using MassTransit; 3 | using MassTransit.Middleware; 4 | using MassTransit.Transports; 5 | using OrdersOrchestrator.Middlewares; 6 | 7 | namespace OrdersOrchestrator.StateMachines; 8 | 9 | public class OrderRequestSagaDefinition : SagaDefinition 10 | { 11 | public OrderRequestSagaDefinition() 12 | { 13 | // Processing up to 5 messages at time 14 | ConcurrentMessageLimit = 5; 15 | } 16 | 17 | protected override void ConfigureSaga( 18 | IReceiveEndpointConfigurator endpointConfigurator, 19 | ISagaConfigurator sagaConfigurator, 20 | IRegistrationContext context) 21 | { 22 | ArgumentNullException.ThrowIfNull(endpointConfigurator, nameof(endpointConfigurator)); 23 | ArgumentNullException.ThrowIfNull(sagaConfigurator, nameof(sagaConfigurator)); 24 | ArgumentNullException.ThrowIfNull(context, nameof(context)); 25 | 26 | // Retrying unhandled exceptions by the saga state machine 27 | sagaConfigurator.UseMessageRetry(config => 28 | { 29 | config.Interval(3, 1000); 30 | config.Ignore(); 31 | }); 32 | 33 | // Configuring a filter for all the registered events in the state machine 34 | sagaConfigurator.UseFilter(new SagaLoggingMiddlewareFilter()); 35 | 36 | endpointConfigurator.ConfigureError(x => 37 | { 38 | x.UseFilters( 39 | new FaultProcessingMiddlewareFilter(context.GetRequiredService()), 40 | new ErrorTransportFilter()); 41 | }); 42 | 43 | base.ConfigureSaga(endpointConfigurator, sagaConfigurator, context); 44 | } 45 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/OrderRequestSagaInstance.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | 4 | namespace OrdersOrchestrator.StateMachines; 5 | 6 | public class OrderRequestSagaInstance : SagaStateMachineInstance, ISagaVersion 7 | { 8 | public string? CurrentState { get; set; } 9 | public string? ItemId { get; set; } 10 | public string? CustomerId { get; set; } 11 | public string? CustomerType { get; set; } 12 | public NotificationReply? NotificationReply { get; set; } 13 | public DateTime CreatedAt { get; set; } 14 | public DateTime UpdatedAt { get; set; } 15 | 16 | // Default props 17 | public Guid CorrelationId { get; set; } 18 | public int Version { get; set; } 19 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/OrderRequestStateMachine.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | using OrdersOrchestrator.StateMachines.CustomActivities; 4 | 5 | namespace OrdersOrchestrator.StateMachines; 6 | 7 | public sealed class OrderRequestStateMachine 8 | : MassTransitStateMachine 9 | { 10 | public OrderRequestStateMachine() 11 | { 12 | // Registering known states 13 | RegisterStates(); 14 | // Registering and correlating events 15 | CorrelateEvents(); 16 | 17 | Initially( 18 | When(OrderRequestedEvent) 19 | .InitializeSaga() 20 | .Activity(config => config.OfType()) 21 | .TransitionTo(ValidatingCustomer), 22 | When(FaultEvent) 23 | .Activity(config => config.OfType()) 24 | .TransitionTo(Faulted)); 25 | 26 | During(ValidatingCustomer, 27 | When(CustomerValidationResponseEvent) 28 | .UpdateSaga() 29 | .Activity(config => config.OfType()) 30 | .TransitionTo(CalculatingTaxes), 31 | When(FaultEvent) 32 | .Activity(config => config.OfType()) 33 | .TransitionTo(Faulted)); 34 | 35 | During(CalculatingTaxes, 36 | When(TaxesCalculationResponseEvent) 37 | .UpdateSaga() 38 | .Activity(config => config.OfType()) 39 | .TransitionTo(NotifyingSourceSystem), 40 | When(FaultEvent) 41 | .Activity(config => config.OfType()) 42 | .TransitionTo(Faulted)); 43 | 44 | WhenEnter(Faulted, 45 | context => context.TransitionTo(NotifyingSourceSystem)); 46 | 47 | WhenEnter(NotifyingSourceSystem, 48 | activityCallback => activityCallback 49 | .NotifySourceSystem() 50 | .Finalize()); 51 | 52 | During(Final, 53 | Ignore(OrderRequestedEvent), 54 | Ignore(CustomerValidationResponseEvent), 55 | Ignore(TaxesCalculationResponseEvent), 56 | Ignore(FaultEvent)); 57 | 58 | // Delete finished saga instances from the repository 59 | SetCompletedWhenFinalized(); 60 | } 61 | 62 | private void CorrelateEvents() 63 | { 64 | Event(() => OrderRequestedEvent, x => x 65 | .CorrelateById(m => m.CorrelationId ?? new Guid()) 66 | .SelectId(m => m.CorrelationId ?? new Guid()) 67 | .OnMissingInstance(m => m.Discard())); 68 | 69 | Event(() => CustomerValidationResponseEvent, x => x 70 | .CorrelateById(m => m.CorrelationId ?? new Guid()) 71 | .SelectId(m => m.CorrelationId ?? new Guid()) 72 | .OnMissingInstance(m => m.Discard())); 73 | 74 | Event(() => TaxesCalculationResponseEvent, x => x 75 | .CorrelateById(m => m.CorrelationId ?? new Guid()) 76 | .SelectId(m => m.CorrelationId ?? new Guid()) 77 | .OnMissingInstance(m => m.Discard())); 78 | 79 | Event(() => FaultEvent, x => x 80 | .CorrelateById(m => m.CorrelationId ?? new Guid()) 81 | .SelectId(m => m.CorrelationId ?? new Guid()) 82 | .OnMissingInstance(m => m.Discard())); 83 | } 84 | 85 | private void RegisterStates() 86 | => InstanceState(x => x.CurrentState); 87 | 88 | public State? ValidatingCustomer { get; set; } 89 | public State? CalculatingTaxes { get; set; } 90 | public State? NotifyingSourceSystem { get; set; } 91 | public State? Faulted { get; set; } 92 | public Event? OrderRequestedEvent { get; set; } 93 | public Event? CustomerValidationResponseEvent { get; set; } 94 | public Event? TaxesCalculationResponseEvent { get; set; } 95 | public Event? FaultEvent { get; set; } 96 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/StateMachines/OrderRequestStateMachineSupportExtensions.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | using MassTransit.SagaStateMachine; 4 | 5 | namespace OrdersOrchestrator.StateMachines; 6 | 7 | public static class OrderRequestStateMachineSupportExtensions 8 | { 9 | public static EventActivityBinder InitializeSaga( 10 | this EventActivityBinder binder) 11 | => binder.Then(context => 12 | { 13 | LogContext.Info?.Log("Order requested: {0}", context.CorrelationId); 14 | 15 | context.Saga.CreatedAt = DateTime.Now; 16 | context.Saga.ItemId = context.Message.ItemId; 17 | context.Saga.CustomerId = context.Message.CustomerId; 18 | }); 19 | 20 | public static EventActivityBinder UpdateSaga( 21 | this EventActivityBinder binder) 22 | => binder.Then(context => 23 | { 24 | LogContext.Info?.Log("Customer validation: {0}", context.CorrelationId); 25 | 26 | context.Saga.CustomerType = context.Message.CustomerType; 27 | context.Saga.UpdatedAt = DateTime.Now; 28 | }); 29 | 30 | public static EventActivityBinder UpdateSaga( 31 | this EventActivityBinder binder) 32 | => binder.Then(context => 33 | { 34 | LogContext.Info?.Log("Taxes calculation: {0}", context.CorrelationId); 35 | 36 | context.Saga.UpdatedAt = DateTime.Now; 37 | }); 38 | 39 | public static EventActivityBinder NotifySourceSystem( 40 | this EventActivityBinder binder) 41 | { 42 | Func, Task> asyncAction = async context => 43 | { 44 | LogContext.Info?.Log("Notifying source system: {0}", context.CorrelationId); 45 | 46 | await context.GetServiceOrCreateInstance>>() 47 | .Produce( 48 | Guid.NewGuid().ToString(), 49 | context.Saga.NotificationReply!, 50 | context.CancellationToken) 51 | .ConfigureAwait(false); 52 | }; 53 | 54 | return binder.Add(new AsyncActivity(asyncAction)); 55 | } 56 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/Transports/FaultTransport.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | using MassTransit.Transports; 4 | 5 | namespace OrdersOrchestrator.Transports; 6 | 7 | public sealed class FaultTransport : IErrorTransport 8 | { 9 | private readonly IServiceScopeFactory serviceScopeFactory; 10 | 11 | public FaultTransport(IServiceScopeFactory serviceScopeFactory) 12 | { 13 | this.serviceScopeFactory = serviceScopeFactory; 14 | } 15 | async Task IErrorTransport.Send(ExceptionReceiveContext context) 16 | { 17 | ArgumentNullException.ThrowIfNull(context, nameof(context)); 18 | 19 | var consumeContext = context.GetPayload(); 20 | 21 | using var scope = serviceScopeFactory.CreateScope(); 22 | var faultTopicProducer = scope 23 | .ServiceProvider 24 | .GetRequiredService>(); 25 | 26 | consumeContext.TryGetMessage(out var incomingConsume); 27 | 28 | var faultEvent = new FaultMessageEvent 29 | { 30 | Event = incomingConsume?.Message, 31 | ExceptionMessage = context.Exception.InnerException?.Message 32 | }; 33 | 34 | await faultTopicProducer 35 | .Produce( 36 | Guid.NewGuid().ToString(), 37 | faultEvent, 38 | Pipe.Execute(p => 39 | { 40 | p.CorrelationId = consumeContext.CorrelationId; 41 | p.Headers.SetExceptionHeaders(context); 42 | }), 43 | context.CancellationToken) 44 | .ConfigureAwait(false); 45 | } 46 | } -------------------------------------------------------------------------------- /src/OrdersOrchestrator/appsettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "Logging": { 3 | "LogLevel": { 4 | "Default": "Information", 5 | "Microsoft.Hosting.Lifetime": "Information" 6 | } 7 | }, 8 | "KafkaOptions": { 9 | "ConsumerGroup": "OrdersOrchestrator.Group", 10 | "Topics": { 11 | "OrderManagementSystemRequest": "ORDER_MANAGEMENT_SYSTEM.REQUEST", 12 | "OrderManagementSystemResponse": "ORDER_MANAGEMENT_SYSTEM.RESPONSE", 13 | "TaxesCalculationEngineRequest": "TAXES_CALCULATION_ENGINE.REQUEST", 14 | "TaxesCalculationEngineResponse": "TAXES_CALCULATION_ENGINE.RESPONSE", 15 | "CustomerValidationEngineRequest": "CUSTOMER_VALIDATION_ENGINE.REQUEST", 16 | "CustomerValidationEngineResponse": "CUSTOMER_VALIDATION_ENGINE.RESPONSE", 17 | "Error": "ERROR" 18 | }, 19 | "ClientConfig": { 20 | "BootstrapServers": "pkc-6ojv2.us-west4.gcp.confluent.cloud:9092", 21 | "SaslMechanism": "PLAIN", 22 | "SecurityProtocol": "SASLSSL", 23 | "SaslUsername": "", 24 | "SaslPassword": "" 25 | }, 26 | "MongoDb": { 27 | "ConnectionString": "", 28 | "DatabaseName": "sagas-db", 29 | "CollectionName": "instances" 30 | }, 31 | "RedisDb": { 32 | "KeyPrefix": "sagas", 33 | "Endpoint": "redis-15237.c124.us-central1-1.gce.cloud.redislabs.com:15237", 34 | "Password": "" 35 | } 36 | } 37 | } 38 | -------------------------------------------------------------------------------- /src/TaxesCalculationEngine/Consumers/TaxesCalculationConsumer.cs: -------------------------------------------------------------------------------- 1 | using Contracts; 2 | using MassTransit; 3 | 4 | namespace TaxesCalculationEngine.Consumers; 5 | 6 | public sealed class TaxesCalculationConsumer : IConsumer 7 | { 8 | private readonly ITopicProducer producer; 9 | 10 | public TaxesCalculationConsumer(ITopicProducer producer) 11 | { 12 | this.producer = producer; 13 | } 14 | 15 | async Task IConsumer 16 | .Consume(ConsumeContext context) 17 | { 18 | ArgumentNullException.ThrowIfNull(context, nameof(context)); 19 | 20 | var key = Guid.NewGuid(); 21 | var calculationFactor = GenerateCalculationFactor(context.Message.CustomerType); 22 | var response = BuildResponse(context.Message.ItemId, calculationFactor); 23 | 24 | // Sending the calculated taxes based on the ItemId and the CustomerType 25 | await producer 26 | .Produce(key.ToString(), response) 27 | .ConfigureAwait(false); 28 | } 29 | 30 | private static int GenerateCalculationFactor(string customerType) 31 | // This might be an enum 32 | => customerType switch 33 | { 34 | "Regular" => 100, 35 | "Premium" => 50, 36 | "Super Premium" => 20, 37 | _ => throw new ArgumentOutOfRangeException() 38 | }; 39 | 40 | private static TaxesCalculationResponseEvent BuildResponse(string itemId, int calculationFactor) 41 | { 42 | var rnd = new Random(); 43 | 44 | var response = new TaxesCalculationResponseEvent 45 | { 46 | ItemId = itemId, 47 | TaxAAA = (decimal)rnd.NextInt64(0, calculationFactor) / 10, 48 | TaxBBB = (decimal)rnd.NextInt64(0, calculationFactor) / 10, 49 | TaxCCC = (decimal)rnd.NextInt64(0, calculationFactor) / 10, 50 | }; 51 | 52 | return response; 53 | } 54 | } -------------------------------------------------------------------------------- /src/TaxesCalculationEngine/Extensions/KafkaRegistrationExtensions.cs: -------------------------------------------------------------------------------- 1 | using Confluent.Kafka; 2 | using Contracts; 3 | using Contracts.Configuration; 4 | using MassTransit; 5 | using TaxesCalculationEngine.Consumers; 6 | 7 | namespace TaxesCalculationEngine.Extensions; 8 | 9 | public static class KafkaRegistrationExtensions 10 | { 11 | internal static IServiceCollection AddCustomKafka(this IServiceCollection services, IConfiguration configuration) 12 | { 13 | ArgumentNullException.ThrowIfNull(services, nameof(services)); 14 | ArgumentNullException.ThrowIfNull(configuration, nameof(configuration)); 15 | 16 | var kafkaOptions = configuration.GetSection("KafkaOptions").Get(); 17 | // clientConfig.SecurityProtocol = SecurityProtocol.SaslSsl; 18 | 19 | services.AddMassTransit(massTransit => 20 | { 21 | massTransit.UsingInMemory((context, cfg) => { cfg.ConfigureEndpoints(context); }); 22 | 23 | massTransit.AddRider(rider => 24 | { 25 | rider.AddProducer(kafkaOptions.Topics.TaxesCalculationEngineResponse); 26 | rider.AddConsumersFromNamespaceContaining(); 27 | 28 | rider.UsingKafka(kafkaOptions.ClientConfig, (riderContext, kafkaConfig) => 29 | { 30 | kafkaConfig.TopicEndpoint( 31 | topicName: kafkaOptions.Topics.TaxesCalculationEngineRequest, 32 | groupId: kafkaOptions.ConsumerGroup, 33 | configure: topicConfig => 34 | { 35 | topicConfig.AutoOffsetReset = AutoOffsetReset.Earliest; 36 | topicConfig.ConfigureConsumer(riderContext); 37 | topicConfig.DiscardSkippedMessages(); 38 | }); 39 | }); 40 | }); 41 | }); 42 | 43 | return services; 44 | } 45 | } -------------------------------------------------------------------------------- /src/TaxesCalculationEngine/Program.cs: -------------------------------------------------------------------------------- 1 | using TaxesCalculationEngine.Extensions; 2 | 3 | var builder = WebApplication.CreateBuilder(args); 4 | 5 | builder.Services.AddCustomKafka(builder.Configuration); 6 | builder.Services.AddControllers(); 7 | builder.Services.AddHealthChecks(); 8 | // builder.Services.AddRequestHandlers(); 9 | 10 | var app = builder.Build(); 11 | 12 | app.UseRouting(); 13 | app.UseHttpsRedirection(); 14 | app.UseAuthorization(); 15 | // app.UseEndpoints(p => p.MapCustomHealthChecks());; 16 | app.MapControllers(); 17 | app.Run(); -------------------------------------------------------------------------------- /src/TaxesCalculationEngine/Properties/launchSettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "profiles": { 3 | "TaxesCalculationEngine": { 4 | "commandName": "Project", 5 | "dotnetRunMessages": true, 6 | "applicationUrl": "https://localhost:7089;http://localhost:5188", 7 | "environmentVariables": { 8 | "DOTNET_ENVIRONMENT": "Development" 9 | } 10 | } 11 | } 12 | } 13 | -------------------------------------------------------------------------------- /src/TaxesCalculationEngine/TaxesCalculationEngine.csproj: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | net6.0 5 | enable 6 | enable 7 | dotnet-TaxesCalculationEngine-8E558102-1BE3-4176-A559-FA88BD3E8B30 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | -------------------------------------------------------------------------------- /src/TaxesCalculationEngine/appsettings.json: -------------------------------------------------------------------------------- 1 | { 2 | "Logging": { 3 | "LogLevel": { 4 | "Default": "Information", 5 | "Microsoft.Hosting.Lifetime": "Information" 6 | } 7 | }, 8 | "KafkaOptions": { 9 | "ConsumerGroup": "TaxesCalculationEngine.Group", 10 | "Topics": { 11 | "TaxesCalculationEngineRequest": "TAXES_CALCULATION_ENGINE.REQUEST", 12 | "TaxesCalculationEngineResponse": "TAXES_CALCULATION_ENGINE.RESPONSE" 13 | }, 14 | "ClientConfig": { 15 | "BootstrapServers": "pkc-6ojv2.us-west4.gcp.confluent.cloud:9092", 16 | "SaslMechanism": "PLAIN", 17 | "SecurityProtocol": "SASLSSL", 18 | "SaslUsername": "", 19 | "SaslPassword": "" 20 | } 21 | } 22 | } 23 | -------------------------------------------------------------------------------- /static/sagas-flow.drawio: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | -------------------------------------------------------------------------------- /static/sagas-flow.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/Igor03/kafka-sagas-demo/041aa66a82682f96ec193665d03ecce1e1fb4898/static/sagas-flow.png --------------------------------------------------------------------------------