eShop (DDD + CQRS + Event Sourcing)
NOTE: Current project still in progress of implementation and contains only base concept of architecture. However, the main idea should be clear enough.
Current repo contains the prototype of shop built with DDD, CQRS and Event Sourcing.
Used technologies
For backend part the following technologies are used:
- ASP.NET Core 5
- Entity Framework Core 5
- Event Store
- Kafka (used only as example)
- Fluent Validation
- MediatR
- NSwag
- Identity Server 4
- Serilog
For front-end part Blazor WebAssembly is used.
All projects except Blazor UI are running in Docker with Docker Compose. Blazor UI should be ran separetly for providing debugging experience. As for now, Blazor Web Assembly do not support debugging in containers.
Projects Overview
Architecture
Current project implemented using Clean Architecture and inspired by Jayson Tailors' repo. However, it is not following his approach completely due to some controversial decisions (which are pretty discussable).
Also, projects follows clean CQRS with Event Sourcing - commands are working with aggregates only, queries are working with EF Core (now with SQLite for easier testing).
The updating of read models are happening using IDomainEvent dispatching to the MediatR handlers.
For events storing and processing - EventStore is using.
Settings
Solution is using Directory.Build.props as centralized storage for common project settings
and centralized package versioning via Directory.Packages.props.
eShop.Common
Current project contains base services, useful utils, etc., which can be used solution-wide.
eShop.Domain
This project contains all domain entities, aggregates and interface IAggregateStore which provides the contract for how entities can be loaded and saved.
Also, this project contains ValueObject abstraction which can help to encapsulate solid value object. Example of it - ValueObjects\Money.
eShop.Application
Application layer which contains the operational and functional logic. The structure of project follows "by-feature" structure - handlers, projections, models, validators are placed in same folder for one feature.
For commands/queries and handlers MediatR is used with custom pipeline extensions (see Behaviors folder). In Persistence folder you can find interface for
EF Core context and entities which will be used for read models.
In Projections folder you can find wrappers around MeditR commands and handlers which contains logic for transferring IDomainEvent
to specified handler for future processing - updating read database, putting messages to Kafka, etc.
eShop.Infrastructure
Current project contains concrete implementations for Application services which are infrastructure-related - event store services (Event Store is used), EF Core implementation (migrations for SQLite) and other.
eShop.Api
This is the presenter part which provides REST API for eShop and wires up everything together. For authentication JWT bearer is used with authority at eShop.Auth. This API also supports serving of Swagger UI and OpenAPI specification via NSwag.
eShop.Auth
This project contains Identity Server 4 and UI for login - the main idea is to provide centralized login/logout (also know as SSO). It is based on standard templates from Identity Server team and uses in-memory storage for clients, scopes and users (just for testing purposes).
eShop.UI.Blazor
Basic Blazor UI project. Does not have any presentation logic for now, but supports auth via JWT Bearer and SSO via eShop.Auth service.
eShop.Domain.UnitTests
Unit tests project for domain aggregates and entities. Now contains the example of unit test for different actions which can be done with ProductWarehouse aggregate.
Common parts
Each project might have DependencyInjection class which encapsulates the setting-up and wiring of dependencies.
For example, in eShop.Application\DependencyInjection.cs you can find extension for registering Application-related dependencies.
Credits
- Inspiration - Jayson Tailors' Clean Architecture
- Event Sourcing inspiration - repo by Alexey Zimarev from his DotNext Event Sourcing workshop
License
This project is licensed with the MIT license.