ITCamp 2019 - Florin Coros - Implementing Clean Architecture
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Clean Architecture as a term is around for a while. However, the path to implement it is not always clear nor easy to follow. When projects fail for reasons that are primary technical, the reason is often uncontrolled complexity. The complexity goes out of hand when the code lacks structure, when it lacks Clean Architecture. In this session, I will show how to achieve consistency by implementing Clean Architecture through structure, rather than relying on discipline only. We will look at some basic building blocks of an application infrastructure which will enforce the way dependencies are created, how dependency injection is used or how separation of the data access concerns is enforced.
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ITCamp 2019 - Florin Coros - Implementing Clean Architecture
- 1. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Implementing Clean Architecture Florin Coroș onCodeDesign.com | www.infiniswiss.com | www.iquarc.com florin@onCodeDesign.com @florincoros .com
- 2. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Many thanks to our sponsors & partners! GOLD SILVER PARTNERS PLATINUM POWERED BY
- 3. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Co-Founder & Partner About me @florincoros Partner https://onCodeDesign.com/training Co-Founder & Partner
- 4. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Implementing Clean Architecture Florin Coroș onCodeDesign.com | www.infiniswiss.com | www.iquarc.com florin@onCodeDesign.com @florincoros .com
- 5. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Why is Architecture Important -- Robert C. Martin, Clean Architecture The goal of software architecture is to minimize the human resources required to build and maintain the required system
- 6. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Decompose - Separation of Concerns Title Title Title Title Title Title Title
- 7. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Manage the Complexity and Size when projects do fail for reasons that are primarily technical, the reason is often uncontrolled complexity
- 8. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals The Architecture is Separation of Concerns and a Set of Rules External Interfaces UI Frameworks Devices Controllers EntitiesEntities Use Cases
- 9. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Implementing the Architecture External Interfaces UI Frameworks Devices Controllers EntitiesEntities Use Cases
- 10. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Structure that Supports the Architecture External Interfaces UI Frameworks Devices Controllers EntitiesEntities Use Cases
- 11. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Clean Architecture External Interfaces UI Frameworks Devices Controllers EntitiesEntities Use Cases http://blog.8thlight.com/uncle-bob/2012/08/13/the-clean-architecture.html Presenter Controller UseCase Implementation Presenter Controller UseCase Implementation UseCase InputAbstraction UseCase OutputAbstraction Dependencies should be in one direction only Source code dependencies can only point inwards
- 12. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Implementing Clean Architecture through Structure • Hide external frameworks to enforce the way they are used • Use assemblies and references among them to enforce rules • Enforce Constructor Dependency Injection that encourages Programming Against Interfaces Create a structure that makes it difficult to write bad code and it makes it easy to write good code, code that follows the architecture and the design
- 13. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Creating a Structure for Clean Architecture <<interface>><<interface>> ILogger +LogError() Logger +LogError() <<public interface>><<public interface>> ILogger +LogError() <<Internal class>><<Internal class>> Logger +LogError()
- 14. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Hide External Libraries from App Code <<Internal class>><<Internal class>> Exception Wrappers <<public Interface>> <<public Interface>> API Interfaces <<Internal class>><<Internal class>> Decorators
- 15. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals <<Interface>> TDataModel IRepository +GetEntities<TDataModel>() <<Interface>> TDataModel IUnitOfWork +GetEntities<TDataModel>() +SaveChanges() Database EfRepository EfUnitOfWork <<Stereotype>> <<DTO>> Order <<DTO>> Person Enforce Separation of Data Access Concerns iQuarcDataAccess
- 16. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals DIP to Enforce Separation of Data Access Concern <<Interface>> IDbContextFactory +CreateContext() Database <<DTO>> Customer<<DTO>> Order<<DTO>> Person UnitOfWork Repository DbContextFactory <<Interface>> TDataModel IRepository, IUnitOfWork +GetEntities() +SaveEntities()
- 17. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals AppBoot: DI Abstractions & Type Discovery <<Interface>> TDataModel <<Interface>> TDataModel IEntityInterceptor +OnLoad() +OnSaving() <<Interface>> TDataModel <<Interface>> TDataModel IDbContextFactory +CreateContext() Database <<DTO>><<DTO>> Customer<<DTO>><<DTO>> Order<<DTO>><<DTO>> Person <<DTO>> Customer<<DTO>> Order<<DTO>> Person UnitOfWork Repository UnitOfWork Repository DbContextFactory <<Attribute>><<Attribute>> ServiceAttribute
- 18. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals <<Attribute>> ServiceAttribute +ServiceAttribute(interface : Type ) Bootstrapper +Run() <<Internal>> DependencyContainerAdapter iQuarcAppBoot AppBoot Hides the DI Framework under Abstractions public interface IPriceCalculator { int CalculateTaxes(Order o, Customer c); int CalculateDiscount(Order o, Customer c); } [Service(typeof(IPriceCalculator), Lifetime.Instance)] interal class PriceCalculator : IPriceCalculator { public int CalculateTaxes(Order o, Customer c) { return 10; // do actual calculation } public int CalculateDiscount(Order o, Customer c) { return 20; // do actual calculation } }
- 19. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Patters for Creating Services that Depend Only on Interfaces [Service(typeof (IOrderingService))] private class OrderingService : IOrderingService { private readonly IRepository repository; private readonly IPriceCalculator calculator; private readonly IApprovalService orderApproval; public OrderingService(IRepository repository, IPriceCalculator calculator, IApprovalService orderApproval) { this.repository = repository; this.calculator = calculator; this.orderApproval = orderApproval; } public SalesOrderInfo[] GetOrdersInfo(string customerName) { var orders = repository.GetEntities<SalesOrderHeader>() ... return orders.ToArray(); } public SalesOrderResult PlaceOrder(string customerName, OrderRequest request) { ... } }
- 20. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Enforce Constructor DI to Prevent Circular Dependencies [Service(typeof(IApprovalService))] class ApprovalService : IApprovalService { private readonly IPriceCalculator priceCalculator; public ApprovalService(IPriceCalculator priceCalculator) { this.priceCalculator = priceCalculator; } ... } [Service(typeof (IPriceCalculator), Lifetime.Instance)] public class PriceCalculator : IPriceCalculator { private readonly IApprovalService approvalService; public PriceCalculator(IApprovalService approvalService) { this.approvalService = approvalService; } ... }
- 21. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals <<Interface>> TDataModel IRepository +GetEntities<TDataModel>() <<Interface>> TDataModel IUnitOfWork +GetEntities<TDataModel>() +SaveChanges() Database EfRepository EfUnitOfWork <<Stereotype>> <<DTO>> Order <<DTO>> Person Encapsulate Data Access Concerns iQuarcDataAccess [Service(typeof (IRepository))] internal class EfRepository : IRepository, IDisposable { private readonly IDbContextFactory contextFactory; private readonly IInterceptorsResolver interceptorsResolver; private DbContext context; private readonly IEnumerable<IEntityInterceptor> interceptors; public EfRepository(IDbContextFactory contextFactory, IInterceptorsResolver resolver) { this.contextFactory = contextFactory; this.interceptorsResolver = interceptorsResolver; this.interceptors = resolver.GetGlobalInterceptors(); } ... }
- 22. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals public interface IRepository { IQueryable<TDbEntity> GetEntities<TDbEntity>() where TDbEntity : class; IUnitOfWork CreateUnitOfWork(); } public interface IUnitOfWork : IRepository, IDisposable { void SaveChanges(); void Add<T>(T entity) where T : class; void Delete<T>(T entity) where T : class; void BeginTransactionScope(SimplifiedIsolationLevel isolation); } Create Separated Patterns for Read-Only and Read-Write
- 23. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Patterns for Read-Only data public class OrdersController : Controller { private readonly IRepository repository; public OrdersController(IRepository repository) { this.repository = repository; } public IActionResult Index(string customer) { var orders = repository.GetEntities<SalesOrderHeader>() .Where(soh => soh.Customer.Person.LastName == customer) .Select(soh => new OrdersListViewModel { CustomerName = customer, Number = soh.SalesOrderNumber, SalesPersonName = soh.SalesPerson, DueDate = soh.DueDate, }); return View(orders); } ...
- 24. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Patterns for Read-Write data public class OrdersController : Controller { ... [HttpPost] [ValidateAntiForgeryToken] public IActionResult PlaceOrder(OrderRequestViewModel model) { ... using (IUnitOfWork uof = repository.CreateUnitOfWork()) { SalesOrderHeader order = uof.GetEntities<SalesOrderHeader>() .FirstOrDefault(o => o.CustomerID == c.ID && o.OrderDate.Month == DateTime.Now.Month); if (order == null) { order = new SalesOrderHeader {Customer = c}; uof.Add(order); } AddRequestToOrder(model, order); uof.SaveChanges(); } ... } }
- 25. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Consistency Creates Optimizations Opportunities internal class EfRepository : IRepository, IDisposable { public IQueryable<T> GetEntities<T>() where T : class { return Context.Set<T>().AsNoTracking(); } public IUnitOfWork CreateUnitOfWork() { return new EfUnitOfWork(contextFactory, interceptorsResolver); } private sealed class EfUnitOfWork : IUnitOfWork { private DbContext context; private TransactionScope transactionScope; private readonly IDbContextFactory contextFactory; public EfUnitOfWork(IDbContextFactory contextFactory, IInterceptorsResolver resolver) { this.contextFactory = contextFactory; this.interceptorsResolver = interceptorsResolver; } }
- 26. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Create Development Patterns in Code
- 27. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Implementing Clean Architecture through Structure External Interfaces UI Frameworks Devices Controllers EntitiesEntities Use Cases <<Attribute>><<Attribute>> ServiceAttribute RepositoryImpl + GetEntities<T>() : IQueriable() + SaveChanges() Hide external frameworks to enforce the way they are used Use assemblies and references among them to enforce rules Enforce Constructor Dependency Injection that encourages Programming Against Interfaces /iQuarc iQuarc onCodeDesign.com/training
- 28. @ITCAMPRO #ITCAMP19Community Conference for IT Professionals Florin Coroș Author & Trainer, onCodeDesign onCodeDesign.com Co-founder & Partner, InfiniSwiss www.infiniswiss.com Co-founder & Partner, iQuarc www.iquarc.com email: florin@onCodeDesign.com blog: onCodeDesign.com tweet: @florincoros https://onCodeDesign.com/training