Tackling Complexity in the Heart of Software Domain-Driven ...pds17.egloos.com/pds/201001/28/18/Domain-Driven_Design.pdf · AOP Grails RoR Naked Object. 8/ ... REPOSITORY, SERVICE,

Tackling Complexity in the Heart of Software

Domain-Driven Design

카페서비스개발팀

조영호

2. What is Domain-Driven Design?

3. Patterns of Domain-Driven Design

목차

4. Conclusion

1. Domain & Software

1. Domain & Software

4 / 문서의 제목

Domain-Driven Design - Book

By Eric Evans

Addison-Wesley, 2003


Domain & Software

The subject area to which the user applies a program is the domain of the software.

The critical complexity of most

software projects is in

understanding the domain itself.


Domain & Software

Software has to

Model the Domain


But...

Spring

ORM

Dependency Injection

Database

J2EE

Ajax

Continuous Integration

Hadoop

Coarse Grained Lock

Strategy

Hibernate

Mockito

ActiveMQ

RoRGrailsAOPNaked Object


Cargo

cargoid

originid

destination

customers clearance(opt)

weight

Haz Mat Code

Routing Service

Database table : cargo_bookings

Cargo_id Transport Load Unload

origin

destination

customers clearance (opt)

populate cargo_bookings

table

"If we give the Routing Service an origin, destination, and arrival time, it can look up the stops the cargo will have to make and, well . . . stick them in the database."

Conversation Based on Technology

2. What is Domain-Driven Design?


Representation[Semantic] Gap

The gap between our mental model of the domain and its representation in software

Low Representation Gap

Name from domain vocabulary

Responsibility derived from domain concept

LionCat


Ice Age of EJB

Cat

High Representation Gap

<<interface>>CatHome

<<interface>>Cat

CatEJB

<<interface>>EJBHome

<<interface>>EJBObject

<<interface>>EntityBean

Domain Concept

Design


Technology Exodus

OO design is more important than any particular implementation technology(such as J2EE, or even Java).

And now important than even Spring or Hibernate


DOMAIN MODEL Pattern

An object model of the domain that incorporates both behavior and data.

Sale

getTotalPrice() : long

setTotalPrice(long)

getLineItems() : Collection

setLineImtes(Collection)

LineItem

getPrice() : long

setPrice(long)

getPrioduct() : Product

setProduct(Product)

Sale

calclulatePrice() : Money

addLineItem(LineItem)

LineItem

calculatePrice() : long

*

TRANSACTION SCRIPT &ANEMIC DOMAIN MODEL RICH DOMAIN MODEL

Back to the Origin of the OO


Continuous Design in Agile

Specification

Test

Design

CodeBig Up-front

Design

Incremental

Design

Refactoring


Analysis = Design = Implementation

Analysis Model

seatId

ReservationSeat

Showing

time

Design Model

seatId

ReservationSeat

Showing

time : TimeOfDay

1

Implementation Model

Showing showing =

showingRepository.getShowingWithLock(showingId);

Reservation reservation =

showing.reserveSeats(seatIds,

adultSeatCount, teenagerSeatCount);

reservationRepository.saveReservation(reservation);


And Finally

Focus on Domain Complexity, not Technology Complexity

Everything is Driven By Domain


And Finally

Tackling Complexity

in the Heart of Software


And Finally

UBIQUITOUS LANGUAGE

MODEL-DRIVEN DESIGN


Model


Model

A system of abstractions that describes

selected aspects of a domain and

can be used to solve problems related

to that domain

A model is not right or wrong, only more or

less useful


Domain Modeling

Documentary Film

A domain modeler chooses particular model for usability


Model & Diagram

A Domain Model is not a particular diagram.

It is the knowledge that the diagram is

intended to convey.

The Diagram is a representation of Model

Not a Model


Model-Driven Design


The MODEL and the heart of the DESIGN

shape each other

Model-Driven Design

DOMAINMODEL

seatId

ReservationSeat

Showing

time

DESIGN

seatId

ReservationSeat

Showing

time : TimeOfDay

1

CODE

Showing showing =







Find the Model that works for Analysis, Design

and Implementation

Model-Driven Design

Lower Representation Gap

Object-Oriented Paradigm is the most Powerful

The Code is an expression of Model


A Programmer is a Modeler.

Hands-On Modelers


UBIQUITOUS LANGUAGE


UBIQUITOUS LANGUAGE

Conversations among

Developers

Discussions among

Domain Experts

Expressions

in the Code

Discussion between

Developers and

Domain Experts

All based on the same language,

derived from a shared Domain Model


UBIQUITOUS LANGUAGE

technical

aspects of

design

technical terms

technical design

patterns

business terms

developers don’t

understand

business terms

everyone uses that

don’t appear in design

domain model terms

names of

BOUNDED CONTEXT

terminology of large-scale

structure

many patterns from

Domain-Driven Design book


Use the Domain Model as the backbone of a Language

UBIQUITOUS LANGUAGE

Use the same language in diagrams, writing, and especially

speech

Use the UBIQUITOUS LANGES in all communication within

team and in the code

One Team, One Language


And Domain-Driven Design

DOMAINMODEL

seatId

ReservationSeat

Showing

time

UBIQUITOUSLANGUAGE

Showing

Reservation

Reservation Seat

CODE

Showing showing =








DOMAINMODEL

seatId

ReservationSeat

Showing

time

UBIQUITOUSLANGUAGE

Showing

Reservation

Reservation Seat

CODE

Showing showing =








DOMAINMODEL

seatId

ReservationSeat

Showing

time

UBIQUITOUSLANGUAGE

Performance

Reservation

Reservation Seat

CODE

Showing showing =








DOMAINMODEL

seatId

ReservationSeat

Performance

time

UBIQUITOUSLANGUAGE

Performance

Reservation

Reservation Seat

CODE

Showing showing =








DOMAINMODEL

seatId

ReservationSeat

Performance

time

UBIQUITOUSLANGUAGE

Performance

Reservation

Reservation Seat

CODE

Performance performance =

performanceRepository.getPerformanceWithLock(

performanceId);







A Showing is...



A Performance is...


Cargo

cargoid

originid

destination

customers clearance(opt)

weight

Haz Mat Code

Routing Service

Database table : cargo_bookings

Cargo_id Transport Load Unload

origin

destination


populate cargo_bookings

table

"If we give the Routing Service an origin, destination, and arrival time, it can look up the stops the cargo will have to make and, well . . . stick them in the database."

Conversation Based on Technology


Cargo

cargoid

weight

Haz Mat Code

Routing Service

Route Specification

origin

destination


Itinerary

Leg

0..1

{Itinerary must satisfy specification}

a Route Specification

an Itinerary satisfyingthe Route Specification

"A Routing Service finds an Itinerary that satisfies a Route Specification.”

Conversation Based on Model

3. Patterns of Domain-Driven Design


Domain-Driven Design & Patterns

DDD is not about patterns such as ENTITY, VALUE OBJECT,

AGGREGATE, REPOSITORY, SERVICE, FACTORY

DDD is a better way of thinking about software design

Patterns may take your software more stable or more maintainable,

but it is the methodology that guides you to deliver something fit

for purpose


DOMAIN MODEL is a King


A King, DOMAN MODEL is RICH, Not ANEMIC

<<interface>>

ShowingRepository

getShowingWithLock(showingId) :Showing

seatId

<<interface>>

SeatState

AbstractSeatState

Reserved

1

0..1

1

0..*

1

0..1

leftSeat

0..1

rightSeat

0..1

nextSeatState

0..1

previousSeatState

<<interface>>

ScheduleService

reserve(showingId, seats,adultSeatCount, teenagerSeatCount) : Reservation

ReservationSeat

-showingRepository -reservationRepositoryScheduleServiceImpl

Occupied Sold

<<interface>>

ReservationRepository

saveReservation(reservation)

ShowingFactory

create(dayOfYear, showingSpecification) : Showing

Showing

time:TimeOfYear

Reservation

amount:Money


<<interface>>

ShowingRepository

getShowingWithLock(showingId) :Showing

seatId

<<interface>>

SeatState

AbstractSeatState

Reserved

1

0..1

1

0..*

1

0..1

leftSeat

0..1

rightSeat

0..1

nextSeatState

0..1

previousSeatState

<<interface>>

ScheduleService

reserve(showingId, seats,adultSeatCount, teenagerSeatCount) : Reservation

ReservationSeat

-showingRepository -reservationRepositoryScheduleServiceImpl

Occupied Sold

<<interface>>

ReservationRepository

saveReservation(reservation)

ShowingFactory

create(dayOfYear, showingSpecification) : Showing

Showing

time:TimeOfYear

Reservation

amount:Money

A King, DOMAN MODEL is RICH, Not ANEMIC

SERVICE

ENTITY

AGGREGATE

VALUEOBJECT

REPOSITORY

FACTORY


A King should be Protected


Layered Architecture

User Interface

Application

Domain

Infrastructure


CONTEXT is a King’s Domain


BOUNDED CONTEXT


BOUNDED CONTEXT

Model

Model

CONTEXTCONTEXT


Translate two UBIQUATIOUS LABUAGES


CONTEXT MAP

Model

Model

CONTEXTCONTEXT

TRNSLATION MAP


CONTINUOUS INTEGRATION

Model

Model

CONTEXT

CONTEXT

CONTINUOUS INTEGRATION per each CONTEXT


A king should learn continuously


DISTILLATION

User Interface

Application

Infrastructure

Domain

COREDOMAIN

GENERICSUBDOMAIIN

COHESIVEMECHANISM

SEGREGATED CORE

ABSTRACTCORE

Refactoring


CONTEXT & MODEL

No duplication...within a context!

Model

Model

CONTEXT

CONTEXT

Single, Unified Model within Any One Context

Duplication between...AOK!

4. Conclusion


No Silver Bullet


Essence of Software

Complexity Conformity

Changeability Invisibility


Essence of Software

Complexity Conformity

Changeability Invisibility

Related to

Domain & Domain Model


Domain-Drive Design

Back to the Basics

Software should model the Domain

Software & Project should be based on the Domain Model

Software that provides rich functionality based on a fundamental understanding of the core domain

Tackling Essence

in the Heart of Software


But Remember... No Silver Bullet


Resources

- Domain-Driven Design, Eric Evans, Addison-Wesley, 2003

- Patterns of Enterprise Application Architecture, Martin Fowler, Addison-Wesley,

2002

- Applying Domain-Driven Design and Patterns, Jimmy Nilson, Addison-Wesley,

2006

- Domain Driven Design Quickly, http://www.infoq.com/minibooks/domain-driven-

design-quickly

- Domain-Driven Design Step-By-Step, http://dddstepbystep.com/cfs-

filesystemfile.ashx/__key/CommunityServer.Components.SiteFiles/Domain-Driven-

Design-_2D00_-Step-by-Step.pdf

- Domain-Driven Design Community, http://domaindrivendesign.org/

- Eternity’s Chit-Chat, http://aeternum.egloos.com/

http://www.infoq.com/minibooks/domain-driven-design-quickly







http://dddstepbystep.com/cfs-filesystemfile.ashx/__key/CommunityServer.Components.SiteFiles/Domain-Driven-Design-_2D00_-Step-by-Step.pdf















http://domaindrivendesign.org/

http://aeternum.egloos.com/

Thank you.

Question.

Documents

Tackling Complexity in the Heart of Software Domain-Driven ...pds17.egloos.com/pds/201001/28/18/Domain-Driven_Design.pdf · AOP Grails RoR Naked Object. 8/ ... REPOSITORY, SERVICE,