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

Elements of DDD withASP.NET MVC &Entity Framework Code FirstGabriel ENEASoftware developer / Maxcode.roCo-founder Joobs.ro – primul portal de joburi IT07 may 2011

Updated:Elements of software design07 may 2011

Agenda Tags# Unit Testing# Enterprise Application Architecture# Dependency Injection# ASP.NET MVC 3# Entity Framework 4.1 Code First# Domain-Driven-Design# Design Patterns

How do you start building anapplication 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 but, in the end, do you achieve 99,99% of unit testing?

Is unit testing realizable? 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?

Lets start thinking to architecturedesign?What? Right, now!?Hey, we have only 1 hour to finish thispresentation! Indeed, but lets try to do something!

Some directionsModeling approaches  Database First Design  Model First DesignLayers  How do we design them?Business rules  Where and how do we implement?Persistence  Should we use an ORM?

Modeling approach - Pros/ConsDatabase First Design  doesnt focus on business rules, only on the way the data is representedModel First Design  Conceptual Design  defines a conceptual model of the entities and relations (UML vs. Domain-Specific Languages)  Code First Design  starts writing code: classes, properties, associations, businesss rules

Layers Presentation Business Data Access

PresentationLayers – any problems? Business Data AccessLayers Coupling!A strong coupling conducts to a hard way to do:  unit testing  refactoring  agile development  or be opened for changes

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!? 

And...whats inappropriate in thiscode?// somewhere in the business layer...public 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; } }...

Lets start with a new approach...DDDDomain-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!

A new default architecture

PersistenceRequirements Persistence Ignorance (PI) / POCO Help Domain Model stay out of infrastructure stuff Decide where to store data Use code generation or an Object Relation (O/R) Mapper  Metadata mapping Support for the Unit of Work pattern

Building blocks of Domain-DrivenDesign

Todays tools(from a web developer perspective)ASP.NET MVC 3  a mature web development platform based on MVC patternEntity Framework 4.1 Code First / NHibernate  helps you focus on your domainDI frameworks  Manage dependencies  Castle Windsor, StructureMap, Spring.NET, Unity, ...

Stop, What is DI? = 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

Dependency Injection Log4netLogger PatientService PatientRepositoy

Dependency Injection 1) creates Builder PatientService Log4netLogger2) inject dependencies 3) uses ILogger

Persistance with EF 4.1 CodeFirstBenefits Mapping based on predefined conventions Support for Query Object pattern (LINQ - IQuerable interface) Fluent API for manual mapping entities to tables, no more .edmx files Entity Validation

ASP.NET MVC 3 and DI support Based on MVC pattern Provides better support for IoC  Views/Controllers Check IDependencyResolver interface  simplify service location and dependency resolutionTService GetService<TService>() { … }IEnumerable<TService> GetServices<TService>() { … }

DemoWhat? We have a demo? Finally!

ConclusionsFocus on  Analyze application dependencies  Business rules  Do refactoring!  Design your Domain  Don’t forget to do Unit testing

Questions?

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/domain-driven-design-quickly

The end…Thank you!Elements of DDD withASP.NET MVC &Entity Framework Code FirstGabriel ENEASoftware developer / Maxcode.roCo-founder Joobs.ro – primul portal de joburi IT07 may 2011

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

by Enea Gabriel on May 12, 2011

Accessibility

Categories

Tags

Upload Details

Usage Rights

2 Embeds 55

Statistics

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

http://www.techgig.com	49
http://10.150.200.102	6