Tagged Questions

Domain-driven design (DDD) is an approach to develop software for complex needs by connecting the implementation to an evolving model.

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3
votes
1answer
224 views

Wouldn't Layer Supertype pattern corrupt our domain model?

a) To my knowledge Domain Objects should for the most part be oblivious to technical aspects of a design. Since I view class inheritance as being a technical solution, wouldn't introducing a Layer ...
0
votes
2answers
255 views

In OnionArchitecture can UI talks directly to datastore or not?

I'm fan of onion architecture but looking for some relaxing solutions in some areas. First of all I was thinking about communicating directly from UI (from controller in mvc) to data on the read ...
0
votes
3answers
203 views

How to handle complex conditions? [duplicate]

We are working on project where we have to manage these conditions. i.e.: A User can save an order under these conditions: User has permission "SaveOrder" Order is in state "shipped" Online Shop is ...
1
vote
2answers
3k views

Anemic Domain Model vs. DDD by definition example(s)?

What is an example of "Business Logic" that should reside in the DomainModel i.e. inside an Entity instead of inside a (Domain) Service, as well as some example logic that should be in a service. ...
2
votes
1answer
918 views

DDD/SOA in (.NET) MVC and Message pattern(s) / Request Response

We're currently considering whether it makes sense (or if the benefits are worth the added code) to introduce a Message based pattern (such as Request Response) into a Domain Driven Design / Service ...
3
votes
1answer
101 views

Handling ground-breaking changes in a production system - Insert intermediate level Management object

As our client request, we are proceeding to change the base of our system. We already have the following structure: A class has many students. (simple typical one - to - many) Now we must change ...
0
votes
1answer
167 views

Shouldn't Location be a Value Object?

Eric Evan's DDD book, Cargo Shipping Example, pg. 168: Location Two places with the same name are not the same. Latitude and longitude could provide a unique key, but probably not a very ...
3
votes
2answers
301 views

Single Responsibility principle VS KISS principle

Let's assume the modeling of User model in a context of a social network. User concept is composed of two notions: Authentication elements like userName/Password/Email etc... Extra data information ...
7
votes
3answers
828 views

Is Domain Entity violating Single Responsibility Principle?

Single responsibility ( reason to change ) of an entity should be to uniquely identify itself, in other words, its responsibility is to be findable. Eric Evan's DDD book, pg. 93: most basic ...
2
votes
2answers
351 views

DDD - Domain Object calling a web service

Is it ok to call a webservice from a Domain object?. As I write the question I am thinking that you should never do that, as it is poor design, but the situation is the following: I have a domain ...
5
votes
1answer
1k views

Unique Value Object vs Entity

Trying to convert some entities into value objects I am stuck in a case where what seems a value object must be unique within an aggregate. Suppose we have a Movie entity which makes the root of an ...
1
vote
1answer
134 views

Entites in Invalid State

I'm looking into developing my entities so that they cannot be in an invalid state. In particular I'm starting with my Customer entity. This would have fields like: Title (enum) FirstName (string) ...
4
votes
2answers
382 views

A design decision in composition or aggregation

I've recently had doubts about some design decisions that I frequently make, so this time I decided to take some time and try to analyze it to find the best solution. I will describe a simple scenario ...
1
vote
2answers
489 views

Converting Business Process Maps into Software

I am fairly new to web application development. I have defined my problem domain through talking to various stakeholders and putting a process map together - basically a flow chart showing the ...
18
votes
5answers
2k views

Unit Testing in a “no setter” world

I do not consider myself a DDD expert but, as a solution architect, do try to apply best practices whenever possible. I know there is a lot of discussion around the pro's and con's of the no (public) ...
7
votes
2answers
724 views

Domain Services as facades

I read .NET Domain-Driven Design with C#: Problem - Design - Solution and I noticed that the author created a domain service for each aggregate root. However, the domain services were only facades to ...
2
votes
2answers
2k views

Identifying Domain Services & Application Services when doing DDD

-I'm trying to figure out how to identify Application Services in my application. I think I can identify a Domain service by 2 things: It acts as a facade to the repository. It holds business logic ...
2
votes
1answer
358 views

Domain Driven Design with an EAV database model

How can one apply DDD to a EAV database model? Consider this EAV database model: How am I supposed to build a domain model if all my entities and their attributes will be stored in the database? ...
6
votes
2answers
309 views

Avoiding ubiquitous language clashes

I have been reading DDD Quickly and wondered about how to avoid naming clashes with technical terms and domain terms. For example, if I commonly used the repository pattern (with classes such as ...
0
votes
3answers
162 views

Should a service use session information?

As an example, if I have a Post service and have a method to retrieve all posts for the logged in user, is it OK to have a findPosts() method that uses an injected Security service to get the user ID ...
5
votes
3answers
624 views

Good practices to implement mappers in a multi-tier application

When you are working with a multi-tier application very often you run into task of converting objects in one layer to objects in another layer. This could be converting database objects into domain ...
5
votes
3answers
1k views

DDD - Aggregate Roots - Dealing with Efficiency and Concurrency

First off, I'll admit that I'm a newbie to DDD and need to read the "blue book". I'm building a system that has an AggregateRoot of type "Match". Each Match can have a collection of "Votes" and also ...
6
votes
2answers
738 views

Unit Test Friendly Domain Driven Design

Many of the readings I've done on DDD, both in books and online, seem to represent code that, often times, is difficult or impossible to unit test. For example, there are numerous samples with static ...
3
votes
5answers
522 views

What is the business cost of anemic domain model

I am looking to quantify the cost or problems of bad software development practices. Specifically can software that has been developed resulting in an anemic domain model be quantifiable in terms of ...
3
votes
1answer
385 views

Aggregate Root and Lots of Data Efficiency

It's more of a scenario, but it isn't far fetched at all. Let's say I have an Aggregate Root (AR) Warehouse which it's used to manage product stock. The Product itself is an AR in a different bounded ...
4
votes
2answers
1k views

Do we achieve 100% Persistence Ignorance solution if we're not using ORM's POCO objects to model the Domain?

Persistence ignorance is ability to retrieve/persist standard objects, where standard objects are considered as classes focused on particular business problem and thus don't contain any ...
3
votes
3answers
1k views

Presentation VS Application layer in DDD

I have trouble drawing a clear line between Presentation and Application layer in Domain Driven Design. Where should Controllers, Views, Layouts, Javascript and CSS files go? Is it in the ...
4
votes
2answers
319 views

DDD and filtering

I am developing an app in ddd maner. So I have a complex domain model. Suppose I have a Fare object and Airline. Each Airline should contain several or much more Fares. My UI should represent Model ...
7
votes
1answer
379 views

Domain Model and Querying

I am new to DDD, having worked only in Transaction-Script apps with an anemic model, or just Big Balls of Mud, so please forgive any terminology I abuse. I am trying to understand the proper ...
1
vote
1answer
161 views

When do domain concepts become application constructs?

I recently posted a question regarding recovering a DDD architecture that became an anemic domain model into a multitier architecture and this question is a follow-on of sorts. My question is when ...
4
votes
3answers
1k views

DDD and Value Objects. Are mutable Value Objects a good candidate for Non Aggr. Root Entity?

Here is a little problem Have an entity, with a value object. Not a problem. I replace a value object for a new one, then nhibernate inserts the new value and orphan the old one, then deletes it. Ok, ...
1
vote
1answer
425 views

Is there a clean separation of my layers with this attempt at Domain Driven Design in XAML and C#

I'm working on an application. I'm using a mixture of TDD and DDD. I'm working hard to separate the layers of my application and that is where my question comes in. My solution is laid out as ...
4
votes
2answers
294 views

Keeping a domain model consistent with actual data

Recently domain driven design got my attention, and while thinking about how this approach could help us I came across the following problem. In DDD the common approach is to retrieve entities (or ...
3
votes
4answers
1k views

DDD: Service or Repository

I am developing an app in DDD manner. And I have a little problem with it. I have a Fare (airline fare) and FareRepository objects. And at some point I should load additional fare information (from a ...
5
votes
1answer
284 views

DDD: service contains two repository

Does it correct way to have two repository inside one service and will it be an application or domain service? Suppose I have a Passenger object that should contains Passport (government id) object. ...
1
vote
1answer
368 views

DDD Model Design and Repository Persistence Performance Considerations

So I have been reading about DDD for some time and trying to figure out the best approach on several issues. I tend to agree that I should design my model in a persistent agnostic manner. And that ...
3
votes
1answer
750 views

How to manage long running background threads and report progress with DDD

Title says most of it. I have found surprising little information about this. I have a long running operation of which the user wants to see the progress (as in, item x of y processed). I also need to ...
2
votes
1answer
935 views

Recovering an anemic domain model into a multitier architecture

I have spent the past several days learning about domain driven design and attempting to apply it to a current project. I decomposed the problem domain into the canonical logical components: domain, ...
13
votes
1answer
2k views

How to choose between using a Domain Event, or letting the application layer orchestrate everything

I'm setting my first steps into domain driven design, bought the blue book and all, and I find myself seeing three ways to implement a certain solution. For the record: I'm not using CQRS or Event ...
5
votes
6answers
231 views

In a team practicing Domain Driven Design, should the whole team participate in Stakeholder meetings?

In my experience, a Software Development Team that comprises: 1 Project Manager 1 Tech Lead 1 - 2 Senior Dev 2 - 3 Junior Dev (Fresh grad) Only the Tech Lead & PM (and/or Senor Dev/s) will ...
3
votes
2answers
545 views

Can the following Domain Entity contain logic for creating/deleting other entities?

a) As far as I understand it, in most cases Domain Model DM doesn't contain code for creating/deleting domain entities, but instead it is the job of layers ( ie service layer or UI layer ) on top of ...
5
votes
6answers
508 views

Should a domain expert make class diagrams?

The domain expert in our team uses UML class diagrams to model the domain model. As a result, the class diagrams are more of technical models rather than domain models (it serves of some sort of ...
3
votes
2answers
80 views

Resources on securing domain models? [closed]

I'm have good resources on both security, domain modelling, and architecture patterns. I've noticed a distinct lack of any suggestion of how and where to integrate security into the systems I build. I ...
7
votes
4answers
2k views

Accessing Repositories from Domain

Say we have a task logging system, when a task is logged, the user specifies a category and the task defaults to a status of 'Outstanding'. Assume in this instance that Category and Status have to be ...
1
vote
1answer
217 views

design pattern advice: graph -> computation

I have a domain model, persisted in a database, which represents a graph. A graph consists of nodes (e.g. NodeTypeA, NodeTypeB) which are connected via branches. The two generic elements (nodes and ...
3
votes
1answer
654 views

Domain Models (PHP)

I have been programming in PHP for several years and have, in the past, adopted methods of my own to handle data within my applications. I have built my own MVC, in the past, and have a reasonable ...
6
votes
3answers
437 views

Resources for popular domain models [closed]

I have come across many situations where I had to build a system for a library or a clinic or other popular domains. The thing is a domain model for a library was probably done 1000 times already with ...
7
votes
10answers
733 views

Should an image be able to resize itself in OOP?

I'm writing an app that will have an Image entity, and I'm already having trouble deciding whose responsibility each task should be. First I have the Image class. It has a path, width, and other ...
6
votes
2answers
421 views

DDD / Layers and legacy systems

I have to refactor a complex C# app (many dialogs, mixed logic and so on). There is a part managing the communication with special hardware equipments (sending commands and receive data via ...
4
votes
1answer
440 views

Is it Ok if Domain Object cross Service Boundary

Is it Ok if Domain Object cross Service-Boundary? Everyone recommend that only DTO should be returned by Services. I am creating simple CRUD application. Is it ok if my service methods return ...