Question

I am on a tight schedule with my project so don’t have time to read books to understand it.

Just like anything else we can put it in few lines after reading books for few times. So here i need some description about each terms in DDD practices guideline so I can apply them bit at a piece to my project.

I already know terms in general but can’t put it in terms with C# Project.

Below are the terms i have so far known out of reading some brief description in relation with C# project. Like What is the purpose of it in C# project.

• Services
• Factories
• Repository
• Aggregates
• DomainObjects
• Infrastructure

I am really confused about Infrastructure, Repository and Services
When to use Services and when to use Repository?

Please let me know if anyway i can make this question more clear

Answer 1

This is my understanding and I did NOT read any DDD book, even the holy bible of it.

• Services – stateless classes that usually operate on different layer objects, thus helping to decouple them; also to avoid code duplication
• Factories – classes that knows how to create objects, thus decouple invoking code from knowing implementation details, making it easier to switch implementations; many factories also help to auto-resolve object dependencies (IoC containers); factories are infrastructure
• Repository – interfaces (and corresponding implementations) that narrows data access to the bare minimum that clients should know about
• Aggregates – classes that unifies access to several related entities via single interfaces (e.g. order and line items)
• Domain Objects – classes that operate purely on domain/business logic, and do not care about persistence, presentation, or other concerns
• Infrastructure – classes/layers that glue different objects or layers together; contains the actual implementation details that are not important to real application/user at all (e.g. how data is written to database, how HTTP form is mapped to view models).

Repository provides access to a very specific, usually single, kind of domain object. They emulate collection of objects, to some extent. Services usually operate on very different types of objects, usually accessed via static methods (do not have state), and can perform any operation (e.g. send email, prepare report), while repositories concentrate on CRUD methods.