domain-driven-design - w3toppers.com

Why does the entity framework need an ICollection for lazy loading?

I think i found the solution…See here for more details: http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/47296641-0426-49c2-b048-bf890c6d6af2/ Essentially you want to make the ICollection type protected and use this as the backing collection for the public IEnumerable public class Product { // This is a mapped property protected virtual ICollection<Photo> _photos { get; set; } // This is an un-mapped property … Read more

Aggregate Root references other aggregate roots

I’ve been in this situation myself and came to a conclusion that it’s too much of a head ache to make child aggregates work in an elegant way. Instead, I’d consider whether you actually need to reference the second aggregate as child of the first. It makes life much easier if you just keep a … Read more

DDD, Anti Corruption layer, how-to?

From the DDD book (Domain-Driven Design: Tackling Complexity in the Heart of Software) by Eric Evans: The public interface of the ANTICORRUPTION LAYER usually appears as a set of SERVICES, although occasionally it can take the form of an ENTITY. and a bit later One way of organizing the design of the ANTICORRUPTION LAYER is … Read more

How to handle set based consistency validation in CQRS?

The solution I went with was to add a System aggregate root that could maintain a list of the current Facility names. When creating a new Facility, I use the System aggregate (only one System as a global object / singleton) as a factory for it. If the given facility name already exists, then it … Read more

Polymorphism: Is ORM entity a Domain Entity or Data Entity?

I’m not entirely sure what you are asking regarding LINQ to SQL, but it’s certainly not the wrong approach to manually create you domain objects. You won’t get properly encapsulated domain objects if you rely on them being code generated. You have got yourself in a muddle regarding the factory pattern. As mouters has pointed … Read more

POCO’s, behavior and Peristance Igorance

I would append another view: POCO states for objects which are not dependent on any framework. The wiki definition of a POJO is much more meaningful to me then the one for POCO: http://en.wikipedia.org/wiki/Plain_Old_Java_Object To paraphrase the wiki definition of the POJO, we can say that POCO object might not be forced to: I. Extend … Read more

DDD Approach to Access External Information

The first thing I noticed was the improper use of the bank account factory. The factory, pretty much as you have it, should be used by the repository to create the instance based on the data retrieved from the data store. As such, your call to accountRepository.FindByID will return either a FixedBankAccount or SavingsBankAccount object … Read more

IQueryable & Repositories – take 2?

DDD Repository should encapsulate data access technicalities: Definition: A Repository is a mechanism for encapsulating storage, retrieval, and search behavior which emulates a collection of objects. It is also responsible for handling middle and end of life of domain objects. Repository interface belongs to Domain and should be based on Ubiquitous Language as much as … Read more

How to pass Current User Information to all Layers in DDD

My approach might not be ideal, but I find it working quite well. Thing what I did – I decided not to use dependency injection pass current user everywhere directly because that was getting too cumbersome and switched to static context. Problem with contexts – they are a bit difficult to manage. This one is … Read more

Communicating between two Bounded Contexts in DDD

When integrating BCs, you have a few options. The reason that calling out to an external BC is discouraged is because it requires for both BCs to be operational at the same time. However, this is often quite acceptable and is simpler than the alternative. An alternative is to have the Game BC subscribe to … Read more