What is "Domain Driven Design" and what can you expect from it?

@ToJans

What is Domain-Driven Design,and what can you expect from it?

The model

Every day of the week I go to work

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The model

Every day of the weekI go to work

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The model: every day of the week

Day of the week?- ?- ?- ?- ?

?- ?

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?- ?- ?- ?- ?- ?- ?


Day of the week?- Monday to Friday- 8.30AM to 5.00PM- Break: 12.30PM, 30mins- Except Friday:

8.30AM to 3.30PM- 1 Saturday/month

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?- ?- ?- ?- ?- ?- ?


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Workday- Schedule- Working hours- Lunch break- Starting late- Overtime- Exceptional Saturday- ...

The model


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Weekday?- Monday to Friday- 8.30AM to 5.00PM- lunch break: 12AM, 30mins- Except Friday:


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Every day of the week?- ?- ?- ?- ?- ?- ?


Weekday?- Monday to Friday- 8.30AM to 5.00PM- lunch break: 12AM, 30mins- Except Friday:


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Every day of the week?- Official holidays- Parental leave- Sick days- Org closed- Economical unemployment- Technical unemployment


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Workday- Schedule- Working hours- Lunch break- Starting late- Overtime- Exceptional Saturday- ...

Calendar- Official holiday- Employee-initiated absence

- Parental leave- Sick days (Carens day)

- Employer-initiated absence- Economical/Technical unemployment- Group holidays

- ...

The model


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The model: every day of the week I go to work

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Workday

Calendar

Schedule

Overtime

Leave

SicknessAbsence

Unemployment

Holiday

ProjectTask

Work log

Billable hour Remote worker

Planning

Deadline

Freelancer Employee

Train Bike

Car Foot

Deliverable

CustomerResource

The model: every day of the week I go to work

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Workday

Calendar

Schedule

Overtime

Leave

SicknessAbsence

Unemployment

Holiday

ProjectTask

Work log

Billable hour Remote worker

Planning

Deadline

Freelancer Employee

Train Bike

Car Foot

Deliverable

CustomerResource

Domain-Driven Design

Domain-Driven Design

Tackling complexity in the heart of software

Eric Evans - @EricEvans0

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DDD in a tweet

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DDD in a tweet: implicit explicit: language

Ubiquitous language

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DDD in a tweet: implicit explicit: language

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DDD in a tweet

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DDD in a tweet: implicit explicit: boundaries

boundaries

Strategic designBounded contexts

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Islands Data ownership

ContractsDependencies

Up- & downstreamOf the shelf or custom built

DDD or not

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InfoQ article by Alberto Brandolini,a.k.a. @Ziobrando

http://www.infoq.com/articles/ddd-contextmapping

Read it!




boundaries

Tactical patternsHow to design the islands?

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Data ownershipTransactional boundaries

Island-specific implementationsExpose behavior, not data

Using ubiquitous language

Aggregates, value objects, repositories, ...

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DDD in a tweet

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DDD in a tweet: implicit explicit: code

Domain logic only

Smallest unit possible

Human-readable

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DDD in a tweet: implicit explicit: code: an example public Catalog(IQueryACatalog Queries, IChangeACatalog Changes,IGenerateProductIds ProductIdGenerator) { this.Queries = Queries; this.Changes = Changes; this.ProductIdGenerator = ProductIdGenerator; }

public void RegisterProduct(ProductId Id, IEnumerable<FareZone> FareZones) { Guard.Against<TooManyFareZonesException>(FareZones.Count() > 3); Guard.Against<DuplicateProductIdException>(Queries.IdExists(Id)); if (Id == ProductId.Empty) Id = ProductIdGenerator.Next(); Changes.ProductRegistered(Id); }

public void RegisterSubscription(ProductId Id, IEnumerable<FareZone> FareZones, PaymentSchedule Schedule) { Guard.With<PaymentScheduleRequiredException>(Schedule != PaymentSchedule.Empty); RegisterProduct(Id, FareZones); }

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DDD in a tweet: implicit explicit: code: an example [TestMethod] public void should_contain_a_product_when_it_is_registered() { Catalog.RegisterProduct(a_product_id, some_fare_zones); Queries.IdExists(a_product_id).ShouldBe(true); } [TestMethod, ExpectedException(typeof(DuplicateProductIdException))] public void should_fail_when_registering_an_existing_id() { Changes.ProductRegistered(a_product_id); Catalog.RegisterProduct(a_product_id, some_fare_zones); } [TestMethod, ExpectedException(typeof(TooManyFareZonesException))] public void should_fail_when_registering_too_many_fare_zones() { Catalog.RegisterProduct(a_product_id, too_many_fare_zones); } [TestMethod] public void should_succeed_when_registering_a_product_with_an_empty_product_id() { Catalog.RegisterProduct(ProductId.Empty, some_fare_zones); Queries.IdExists(a_fake_ProductIdGenerator.IdToReturn); }

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DDD in a tweet

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DDD in a tweet: evolve your model

“All models are wrong, but some are useful”

George E.P. Box

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“Software is a learning process, working code is a side effect”

Alberto Brandolini - a.k.a @Ziobrando

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DDD in a tweet: evolve your model: modellathon

Kazachstan Education system

pic by Stijn Volders

a.k.a. @ONE75

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“Il semble que la perfection soit atteintenon quand il n'y a plus rien à ajouter,

mais quand il n'y a plus rien à retrancher.”

Antoine de Saint-Exupéry

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DDD: common mistakes

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DDD: common mistakes

Using DDD everywhereIgnoring strategic design

Sharing state or codeBDUF

Frameworks vs librariesSelling DDD

DDD is evolving (f.e. CQRS-style)

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DDD: the biggest mistake

How do I … ?

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DDD: avoid the biggest mistake

“Ask for experience, not for advice”

Yves Lorphelin, a.k.a. @YLorph

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DDD: how to get started

“A journey of a thousand milesbegins with a single step”

Lao Tzu

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The books

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and...Go to Julie Lerman’s talk later today:

“Domain-driven design for the Database Driven-Mind”

room 3 - 11.30AM(Author of http://bit.ly/PS-DDD)

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Newsgroups:Yahoo: Domain-driven design / Google: DDD-CQRS

Communities:@DDDBE / #CQRSBeers

Events:DDD eXchange London - Friday, June 12th 2015

AND … <DRUMROLL>

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Questions

http://tojans.me - @ToJans

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http://tojans.me

http://tojans.me

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Date post:	22-Aug-2015
Category:	Software
Upload:	tom-janssens
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