UML Structural Models

Question 1

When is modelling in software development relevant?

Answer 1

Throughout the entire development process.

Analysis
System design
Detailed design
Implementation
Quality Assurance
Maintenance

Question 2

What are the three structural diagrams we have discussed in class?

Answer 2

Class diagrams, object diagrams, deployment diagrams

Question 3

Class diagram:
How to draw class

Answer 3

Rectangle with name.
Three sections:
name, attributes, methods

Question 4

Class diagram:

Attribute

Answer 4

In second section.

<Visibility> <name> : <type>
</type></name></Visibility>

Question 5

Class diagram:

Method

Answer 5

In third section.

<Visibility> <name>() : <type>

<Visibility> <name>(<parameters>) : <type>

Parameter: <name> : <type>
</type></name></type></parameters></name></Visibility></type></name></Visibility>

Question 6

Class diagram:
Visibility modifiers

Answer 6

Private -
Public +
Protected #

Question 7

Class diagram:
Class members

Answer 7

Underlined
Same value/declaration for all objects of class
Static in Java

Question 8

Class diagram:
Comments

Answer 8

Add little note with flap in right corner and dotted line to where the comment is for.

Question 9

Class diagram:
Associations

Answer 9

Specifies that there is a reference between the involved entities.

Reference to another class’ objects

Question 10

Class diagram:
Aggregation

Answer 10

Empty diamond arrow.
A special case of association.

The objects of the referenced class are “owned” (unlike plain association)
The aggregation implies a relationship where the child can exist independently of the parent.

Library is made up of one or more books. Diamond shape near parent class.

Question 11

Class diagram:
Composition

Answer 11

Filled out diamond arrow.
A special case of association.

The objects of the referenced class are “owned” (unlike plain association)
A composition means that the referenced object is ‘part of’ the referencing object – manages the lifecycle of the referenced object.

That is, the contained class will be obliterated when the container class is destroyed. For example, a shoulder bag’s side pocket will also cease to exist once the shoulder bag is destroyed.

Again diamond at parent class.

Question 12

Class diagram:
Abstract classes and methods

Answer 12

Writing in italics.

The UML Generalisation denotes inheritance similar to Java albeit with a different terminology.
Sub-class == specialisation
Super-class == generalisation

Question 13

Class diagram:
Interface

Answer 13

Are marked by so called stereotypes.
In first section:
«interface»

<name>
Second:
nothing
Third:
<visibility> <name>() : <type>
</type></name></visibility></name>

Question 14

Class diagram:
enumeration

Answer 14

Are marked by so called stereotypes.
Two sections.
«enumeration»

<name>

all the different categories
</name>

Question 15

Protected visibility in UML vs Java

Answer 15

UML: visible only for class and subclasses
Java: Visible for class, subclass, and same package.

Question 16

Multiple inherence UML vs java

Answer 16

java doesn’t support multiple inherence but UML does

Question 17

Class diagram:
Inheritance (or generalisation)

Answer 17

A generalisation is a taxonomic relationship between a more general classifier and a more specific classifier.

The relationship is displayed as a solid line with a hollow arrowhead that points from the child element to the parent element.

I.e. class Rectangle extends BaseShape
relationship between abstract class and subclasses of it

Question 18

Class diagram:
Association

Answer 18

Simple association is just regular arrow ->
A structural link between two peer classes.

Question 19

Class diagram:
Dependency

Answer 19

An object of one class might use an object of another class in the code of a method. If the object is not stored in any field, then this is modelled as a dependency relationship.

Exists between two classes if changes to the definition of one may cause changes to the other (but not the other way around).

The relationship is displayed as a dashed line with an open arrow.

I.e. person takes object book and return true if read.

Question 20

Class diagram:
Realisation

Answer 20

Realization is a relationship between the blueprint class and the object containing its respective implementation level details. This object is said to realize the blueprint class. In other words, you can understand this as the relationship between the interface and the implementing class.

I.e. between an interface and class that implements interface. Arrow pointing on interface.

Dashed line with filled out arrow.

Question 21

Object diagrams primary use

Answer 21

Is to make an example of instances of classes, e.g. to explain certain value constellations.

Show example of objects with their specific values.

Question 22

Object diagram, how to draw object

Answer 22

Two sections:

name: Class (underlined)
attribute = value

example:
norbert : TurtleBot (underlined)
name = “Norbert”

Question 23

Object diagram:
Object

Answer 23

Instance of class
Header is underlined
Name is optional i.e. :TurtleBot

Question 24

Object digram
Attributes

Answer 24

Have values (if relevant)

Question 25

Object digram
Methods

Answer 25

Omitted

Question 26

Object diagram
Associations

Answer 26

Have no arrow

Question 27

Deployment diagram primary use

Answer 27

UML deployment diagrams specify which parts of a distributed application run on which part of the infrastructure.

As many of today’s software systems do not run on a single computer system anymore, an essential activity of software design is to determine how the parts of a software system should be distributed.

Question 28

Deployment diagram how to draw

Answer 28

3D box
«device»
:name

One is called a node.
Nodes describe “instances” of specific pieces of hardware (web server, laptop, database server, etc.)

May have attributes (relevant properties CPU rate, RAM)
May be nested

Question 29

Deployment diagram
Artifact

Answer 29

Generally just “pieces of software” and may encompass components, objects, documents etc.

Denoted by :Name in a rectangle.

Question 29

Deployment diagram
Communication paths

Answer 29

Connect nodes
Line between nodes
May have stereotypes like «web», «cable»
May have multiplicities, i.e., A «pc» can connect to one or more «robot», a «robot» is connected by one «pc».