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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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 ...
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How to use BDD to unit test a compiler?

My team is writing a compiler for a domain-specific language (DSL) which will be integrated into an IDE. Right now, we are focused on the analysis phase of the compiler. We are not using any existing ...
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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 ...
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Are Persistence-Ignorant objects able to implement lazy loading?

Persistence Ignorance is an application of single responsibility principle, which in practice means that Domain Objects (DO) shouldn't contain code related to persistence, instead they should only ...
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Computed Values and Simple Reads - A nagging pain for my Domain Driven Designs!

The problem I continually face is how to deal with computed values driven by domain logic while still working efficiently against the data store. Example: I'm returning a list of Products from my ...
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Duplication in parallel inheritance hierarchies

Using an OO language with static typing (like Java), what are good ways to represent the following model invariant without large amounts of duplication. I have two (actually multiple) flavours of the ...
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How to document a Ubiquitous Language?

Our company is in the process of converting a lot of manual business processes (and the associated institutional knowledge) into new enterprise software. The project is going really well, but as we ...
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175 views

Does a pattern for “houskeeping” a NoSQL DB with eventual consistency exist?

I'm working with a NoSQL DB with eventual consistency. My software is not only inserting Java Objects in JSON but also creating secondary indices for cross-referencing and similar things. Due to the ...
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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. ...
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Design pattern for “operation on object allowed, only if object is in certain state”

For example: Only job applications that are not yet in review or approved, can be updated. In other words, a person can update his job appliance form until HR starts reviewing it, or it's already ...
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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 ...
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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 ...
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Lookup Tables: Are they a leak in the domain model?

You are building a system that keeps track of Companies. Those companies have Contacts. Those contacts are often specialists that only answer certain types of questions, such as Billing/Payment, ...
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DDD: Can immutable objects also be entities?

I've read countless posts on differences between Entities and Value objects and while I do think that at least conceptually I understand how the two differ, it appears that in some of these posts ...
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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 ...
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520 views

DDD Architecture in a MVC web application

I am putting together a web application using DDD however am strugleing to put the text book DDD model into a real world MVC application. I currently have these layers: Controllers > ...
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In domain driven design, how do I convert a database table with a primary key into a Value Object?

Lets suppose there's a database schema defined like this: Person.mail_address_key ----- Address.address_key Person.billing_address_key ----- Address.address_key A Person has a mailing address and a ...
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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 ...
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Inject dependency as method parameter instead of constructor parameter

I'm using an ORM which doesn't allow me to inject dependencies in the constructor. Let's say I'm using DDD for the business logic, and the MVC pattern for the UI. Now one of my domain objects needs ...
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“Implementing DDD” by Vernon: value object or not?

On page 382 of this book there is a passage talking about using value objects in aggregates, under the (entity) root. There is an example of Product that, besides other values, contains a ...
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611 views

To Repository Or Not To Repository

When I first learnt about Domain Driven Design, I was also introduced to the repository and unit of work patterns that once seemed to be top notch for the cool kids that threw SQL queries like ...
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Which is the preferable design for my Gateway? [closed]

I'm writing a Gateway class that extracts information from a HTML document. One of the responsibilities of the class is to traverse a table in the document and extract data from its rows. I'm trying ...
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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 ...
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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 ...
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How to deal with queries that do not return full entities in Domain Driven Design?

In my application, I have a listing of information that is deducted from a query that combines information from several entities. In itself, a very common situation. Now, the corresponding repository ...
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Model relationships with DDD (or with sense)?

Here is a simplified requirement: User creates a Question with multiple Answers. Question must have at least one Answer. Clarification: think Question and Answer as in a test: there is one ...
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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 ...
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Confusion about the meaning of the word aggregate in domain driven design

In a discussion about domain driven design I have learned the different people seem to think of different things when using the word aggregate. The main difficulty is that some people use the word ...
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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 ...
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563 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 ...
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Should I use an aggregate root when designing my repository?

I have an entity that is called Master which is composed of a number of Slave entities. There can only be one Master in my database and I want to query repositories to get the Slave for a given id. ...
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Where should business logic go in a layered architecture?

First of all, i'm not talking about validation in the sense of the nullability or length of a field like in this and this questions where we can use isValid() methods in business classes or an ...
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Is DDD not appropriate for my website or should I introduce a Query Layer?

I have inherited an ASP.NET website application and the previous developer has used what I believe are some DDD concepts. I am new to DDD and I have to admit I am struggling with the practical side of ...
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Persisting Large/Complex Entities with the Command Pattern — Am I doing it right?

I am in the process of designing and building a large-scale inventory management software-as-a-service that will, hopefully, live a long and fruitful life. Therefore I am exerting a lot of effort ...
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What and how much domain code should be put in an F# module

According to recommendations given here, F# modules should correspond to DDD bounded contexts, i.e. subdivisions of a business domain. The bounded context I'm working on right now has 2 aggregates ...
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Refactoring jQuery spaghetti code to use DDD [closed]

Most of my client side code ends up as a long script in one file the mostly looks like this: <script> function someFunction1(){/*...*/} function someFunction2(){/*...*/} ... var ...
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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 ...
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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 ...
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DDD CQRS - per-query and per-command authorization

Summary Should authorization in CQRS/DDD be implemented per-command/query or not? I am developing for the first time an online application using more or less strictly the DDD CQRS pattern. I bumped ...
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CQRS + Event Sourcing: (is it correct that) Commands are generally communicated point-to-point, while Domain Events are communicated through pub/sub?

Didn't know how to shorten that title. I'm basically trying to wrap my head around the concept of CQRS ( http://en.wikipedia.org/wiki/Command-query_separation) and related concepts. Although CQRS ...
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ID properties on Domain objects in DDD

In my domain I have an Account object. e.g. class Account { public string Number; public string SortCode; } Within the context of DDD, should this account object have an ID property? The ...
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How to model an address type in DDD?

I have an User entity that has a Set of Address where Address is a value object: class User{ ... private Set<Address> addresses; ... public setAddresses(Set<Address> ...
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Equivalent of Domain Driven Design for functional programming languages

I really love the idea of domain driven design, however, as I'm learning Go, I'm wondering if there's the equivalent of DDD that's aimed at an effectively more functional language?
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Tools to support learning a new business domain [closed]

Suppose you just accepted a job, writing code in an industry sector that you've never worked in before. To be effective, you want to immerse yourself in the business domain - to understand the ...
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Scrum, DDD, and front-end development in an enterprise environment

So, I've been working for a bank for the past 4 years. My main responsibility has been online banking. Over the past year, we've been implementing the scrum methodology. We've also changed to domain ...
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Data access for composable applications

I'm wondering if anyone can share their thoughts, experience and guidance on how to approach the data access layer for a composable application? By composable application, I mean an application with ...
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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, ...
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Encapsulation in Domain Driven Design models?

I am using EF Code First and I had a model like below. public class Account { [Required] public string AccountNo { get; set; } [Required] public decimal Balance { get; set; } } I ...
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What is a value object in domain-driven design?

I have an entity and I've realised that there is a group of properties that work together. So, I moved them to a value object (together with their behavior) and now I have a reference from my entity ...
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DDD – A rookie’s unanswered questions

I’ve decided to use DDD in one of my pet projects to find out what the fuss is about! Let me start off by saying that this (DDD) is the way software SHOULD be written, I’ve seen some strange patterns ...