Chapter 6. The Life Cycle of a Domain Object

Question 1

___________ mark off the scope within which ________ have to be maintained at every stage of the life cycle.

Answer 1

Aggregates
invariants

DDD, p. 124

Question 2

Factories and repositories operate on ________, encapsulating the complexity of specific _________.

Answer 2

aggregates
life cycle transitions

DDD, p. 124

Question 3

With many users consulting and updating different objects in the system, we have to prevent _________ to interdependent objects

Answer 3

simultaneous changes

DDD, p. 126

Question 4

An aggregate is a ________ of associated objects that we treat as a unit for the purposes of __________

Answer 4

cluster
data changes

DDD, p. 126

Question 5

Each aggregate has a ________ and a _______.

Answer 5

root
boundary

DDD, p. 126

Question 6

The __________ defines what is inside the aggregate.

Answer 6

boundary

DDD, p. 126

Question 7

The root is a ________, _________ contained in the aggregate.

Answer 7

single, specific entity

DDD, p. 126-7

Question 8

The root is the only member of the aggregate that _________ are allowed to __________.

Answer 8

outside objects
hold reference to

DDD, p, 127

Question 9

Objects within the boundary may ________ to each other

Answer 9

hold references to

DDD, p. 127

Question 10

In an aggregate, entities other than the root have a ______ identity.

Answer 10

local

DDD, p. 127

Question 11

Invariants are ________ rules that must be maintained whenever data ________.

Answer 11

Consistency
Changes

DDD, p. 128

Question 12

Any rule that _______ aggregates will not be expected to be _______ at all times.

Answer 12

spans
up-to-date

DDD, p. 128

Question 13

The ______ applied within an aggregate will be _________ with the ________ of each transaction.

Answer 13

invariants
enforced
completion

DDD, p. 128

Question 14

In the DDD UML models, invariants are indicated by: __________

Answer 14

rules within { }
e.g., {mileage = sum(Position.mileage)}

DDD, p.1 28

Question 15

The root entity has a _______ identity and is ultimately responsible for checking _________.

Answer 15

global
invariants

DDD, p. 128

Question 16

The root may hand a _______ of a value object to another object.

Answer 16

copy

DDD, p. 129

Question 17

Only ______ can be obtained directly with database queries. All other objects must be found by __________.

Answer 17

aggregate roots
Traversal of associations

DDD, p. 129

Question 18

Objects within the aggregate can hold reference to other __________.

Answer 18

aggregate roots

DDD, p. 129

Question 19

A ______ operation much remove everything within the aggregate boundary ________.

Answer 19

delete
at once

DDD, p. 129

Question 20

When a change to ________ with the Aggregate boundary is committed, all __________ of the whole Aggregate ___________.

Answer 20

any object
all invariants
must be satisfied.

DDD, p. 129

Question 21

Factories provide _______ when the creation of an object or aggregate become complicated or reveals too much of the internal structure.

Answer 21

encapsulation

DDD, p. 136

Question 22

A program element whose responsibility is the creation of other objects is called a ______.

Answer 22

factory

DDD, p.138

Question 23

Complex object creation is a responsibility of the ________ layer, yet that task does not belong to the objects that express the _______.

Answer 23

domain
model

DDD, p. 137

Question 24

One requirement for a good factory is that each creation method is _______ and enforces all ______ of the created object or aggregate.

Answer 24

atomic
invariants

DDD, p. 139

Question 25

One requirement for a good factory is that the factory should be abstracted to the _______, rather than the concrete class(es) created

Answer 25

type desired

DDD, p. 139

Question 26

If you need to add elements inside a preexisting aggregate, you might create factor method here…

Answer 26

on the root of the aggregate.

DDD, p. 139

Question 27

A factory should be attached only to an object that has a _______ relationship with the product.

Answer 27

close natural

DDD, p. 141

Question 28

A factory method can be put on an object that is closely involved in spawning another object, although it doesn’t _____ the product once it is created.

Answer 28

own

DDD, p. 139

Question 29

Gamma (1995) talks about three special purpose creation patterns….

Answer 29

Factory Method
Abstract Factory
Builder

DDD, p. 139

Question 30

When there doesn’t seem to be a natural host for a implementation, we must create a ______ factory object or service.

Answer 30

dedicated

DDD, p.