DOMAIN DRIVEN DESIGN DDD 

BY ERIC EVANS 

150 PAGES 

WHAT IS DOMAIN? • Business or whatever activity we are trying to assist with the software 

• Assembly parts != Car • Vision • Specification • Architecture 

• Communication between experts & developers • Develop model together 

UBIQUITOUS LANGUAGE • Model driven: Based on the Domain Model • Building up a common, rigorous language between developers and users • UML • Software doesn't cope well with ambiguity 

BOUNDED CONTEXT • Model gets bigger • Bound context • Domain & sub domain Domain Sub Domain Service Sub Domain Service Sub Domain Service 

• Product in Catalog domain • Product in Stock Management domain Product image, title, price product code, storage 

• Subdomain has its own model • Each model has bounded context 

BUILDING BLOCKS Model Driven Development 

LAYERED ARCHITECTURE 

ENTITY • Not defined by their attributes • Continuity • Identity 

VALUE OBJECT • These objects describe characteristics of a thing. • Immutable during lifecycle 

SERVICE • oo manger • significant process or transformation in the domain is not a responsibility of an ENTITY or VALUE OBJECT, add SERVICE • The interface is defined in terms of other elements in the domain model • Stateless 

MODULE • Highly cohesive • Low coupling • Derived from the Ubiquitous Language 

AGGREGATE • Logical boundary for things that can change in a business transaction of a given context. • Reduce many to many relationship • Root: outside objects holds references to 

AGGREGATE 

FACTORY • Produces complicated aggregates or sometimes also entities and value objects 

REPOSITORY • Interfaces for storing and retrieving Aggregate Roots 

• Refactoring • Maintaining model integrity • … 

THANK YOU!