Introduction To Domain Driven Design

Introduction to
Domain-Driven Design
Paul Rayner
Solutions Architect

The principle that we should be
focusing on the deep issues of the domain
our users are engaged in,
that the best part of our minds should be
devoted to understanding that domain, and
collaborating with experts in that domain to
wrestle it into a conceptual form
that we can use to
build powerful, flexible software.
Eric Evans
DOMAIN-DRIVEN DESIGN

The overwhelming problem with software development
is that
everything is part of the design process.
“What Is Software Design?” - Jack Reeves

For reasons that I do not understand,
reasonably intelligent people insist upon confusing the concept of
design as process
versus
design as product
“What Is Software Design? – 13 Years Later” - Jack Reeves

design as product

design as process
DOMAIN MODEL

UBIQUITOUS
LANGUAGE

Domain-Driven Design applies whenever
we are operating in a complex, intricate domain
Make the software a reflection of the domain Incorporate and express the
core concepts and elements of the domain
Precisely realize the relationships between them.

John,
In the system for Client A, please tell me the source for populating the field Retail Price?
Pam
Accountant
We Rock!, Inc.
Pam,
Retail Price = ARRAMT in ARRTRXPF ...
It comes out of the BARCSTPF ... either directly or as calculated percentage from BARCSTPF.
John
Developer
We Rock!, Inc.

Claire <Business Analyst>,
Can you please tell me what the @*&#^&^# field John is referring to?
I haven't memorized all of the column headers in the tables in the system that I never see . . . :-)
I'm guessing he means the product maintenance menu, and the screens 1 - 3 and the field marked "sale price" . . .
Pam
Accountant
We Rock!, Inc.

LAYERED
ARCHITECTURE

http://jeffreypalermo.com/blog/the-onion-architecture-part-1

ENTITIES

Identity…

VALUE OBJECTS

AGGREGATES

SERVICES

FACTORIES

REPOSITORIES

BOUNDED CONTEXT

Thanks to Dave Laribee (codebetter.com/blogs/david_laribee) for permission to use his presentation ideas
RESOURCES

Paul Rayner
paul@virtual-genius.com
303.374.4370
@virtualgenius (Twitter)
http://virtualgenius.spaces.live.com
Solutions Architect