Elements of DDD with ASP.NET MVC & Entity Framework Code First v2

Elements of DDD with ASP .NET MVC &Entity Framework Code First Gabriel ENEA, Technical Director MAXCODE.nlCo-founder Joobs.ro – the first IT job portal in Romania CodeCamp member / Iași gabriel.enea@maxcode.ro / gabrielenea.blogspot.com / @dotnet18 Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

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Agenda# Unit Testing challenges# Today Architectural Design# New approach: Domain-Driven-Design# Today’s Tools (@web)# Demo• Q&A Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Application requirementsDEMO Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

UNIT TESTING CHALLENGES Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

How do you test it?Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Testing on componentsPremium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

How do you start building an application architecture?Focus on?• building an architecture from scratch• thinking about how to achieve unit testing• start with modeling the database schema and data relations• using drag & drop programming• modeling the domain entities, relations, business rules• reusing existing code?• but, in the end, do you achieve 99,99% test code coverage? Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Is unit testing achievable? 100%?Yes or No? Who knows?Maybe not! Possible answers:• The customer doesnt understand this need• Neither the management staff• Instead, everyone expects you to write the perfect code• As developers, every time we say: we need time to do it right!• But, do we need time or we dont know how to achieve it? Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

TODAY ARCHITECTURAL DESIGN Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Lets start thinking to architecture design What? Right, now!? Hey, we have only 1 hour to finish this presentation!  Indeed, but lets try to do something! Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

What stops 100% unit testing?1. Layers – How do we design them?2. Business rules – Where and how do we implement?3. Persistence – Should we use an ORM? … Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

1 - Layers Presentation Business Data AccessPremium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

1 - Layers – any problems? Presentation BusinessLayers Coupling! Data AccessA strong coupling conducts to a hard way to do: – unit testing – refactoring – agile development – or be opened for changes Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

2 - Business rulesWhere should these be located? – Database – Business layer – User Interface (aka code behind!)How do we test them? – Running the application – Automatically, maybe using unit tests – Or we should let the customer test them!?  Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

And...whats inappropriate here?// somewhere in the business layerpublic class Patient { public DateTime Birthdate { get; set; } public int Age { // computed value get { return DateTime.Now.Year - this.Birthdate.Year; } Strong coupling! } public bool IsAdult { // business rule get { return this.Age >= 18; } }... Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

3 - PersistenceRequirements• Persistence Ignorance / POCO• Help Domain Model stay out of infrastructure stuff• Decide where to store data (NoSQL?)• Use code generation or an Object Relation (O/R) Mapper – Metadata mapping• Support for the Unit of Work pattern Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

NEW APPROACH: DDD Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Lets start with a new approach...Domain-Driven-Design• What is Domain?A new default architecture where:• the database is not the first focus• the layers are loosely coupled• the business rules are within the application Domain• it is easier to achieve unit testing• Why? Today we have the tools! Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

A new default architecture - DDD Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Building blocks of DDDPremium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

TODAYS TOOLS Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Todays tools(from a web developer perspective)Dependency Injection frameworks – Manage dependencies – Castle Windsor, StructureMap, Spring.NET, Unity, ...ASP.NET MVC 3 – a mature web development platform based on MVC patternEntity Framework 4.1 Code First / NHibernate – helps you focus on your domain Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

What is Dependency Injection?• = DI.Equals(IoC); // true or false?• IoC = Inversion of Control• DI = Dependency Injection• Helps you to decouple the application dependencies – Logging mechanisms (log4net, Enterprise Library Logging Application Block, ...) – Persistence mechanism (direct access to database, ORM) – User Interface dependencies on Domain services – Layers Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Dependency Injection Log4netLoggerPatientService PatientRepositoy Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Dependency Injection 1) creates Builder PatientService Log4netLogger2) inject dependencies 3) uses ILogger Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

ASP.NET MVC 3 and DI support• Based on MVC pattern• Provides better support for IoC – Views/Controllers• Model Validation support• Check IDependencyResolver interface – simplify service location and dependency resolutionTService GetService<TService>() { … }IEnumerable<TService> GetServices<TService>() { … } Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Persistance with EF 4.1 CodeFirst1st version benefits:• CodeFirst development• Better POCO support• Mapping based on predefined conventions (Convention over configuration)• Fluent API for manual mapping entities to tables, no more .edmx files• Built-in Model-Level Validation• Dynamic database creation and dropping Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

DDD architecture with ASP.NET MVC 3, Unity, Entity FrameworkCodeFirst 4.1DEMO Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

ConclusionsFocus on – Analyze application dependencies – Business rules – Do refactoring! – Design your Domain – Don’t forget to do Unit testing Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

ResourcesBooks• Domain-Driven Design, Tackling Complexity in the Heart of Software, by Eric Evans• Applying Domain-Driven Design and Patterns, With Examples in C# and .NET, by Jimmy NilssonOnline resources• http://domaindrivendesign.org/• http://www.infoq.com/minibooks/domai n-driven-design-quickly Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Elements of DDD with ASP.NET MVC & Entity Framework Code FirstQ&A Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

Don’t forget!Get your free Azure pass! We want your feedback!• 30+15 days, no CC req’d • Win a WP7 smartphone – http://bit.ly/ITCAMP11 – Fill in your feedback forms – Promo code: ITCAMP11 – Raffle: end of the day Premium conference on Microsoft’s Dev and ITPro technologies @itcampro / #itcampro

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Elements of DDD with ASP.NET MVC & Entity Framework Code First v2

by Enea Gabriel on May 30, 2011

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Elements of DDD with ASP.NET MVC & Entity Framework Code First v2 — Presentation Transcript