Uml Intro

UML – Unified Modeling Language ● ●

●

Visual language. Used to model systems and system development –

system requirements

–

system structure

–

system behaviors

Object-Oriented –

but this doesn't mean implementation must be OO. UML Intro

1

Software Engineering History ●

In the old days : structural programming –

●

procedures, functions, collections of functions, etc.

Structured Analysis and Design –

based on some formal design documents ●

●

data flow, state models, task diagrams

OOP and Object Oriented Design –

Booch, OMT, OOSE: competing methods. ●

unified as "UML"

UML Intro

2

Why learn UML? ●

●

It's good to study formal design techniques, models, languages, etc. UML is an industry standard. –

●

●

lots of tools are available.

Many large software systems are modeled using UML in the real world. It's fun to draw pictures with stick figures!

UML Intro

3

Software Methodology ●

●

The process used (by designers, programmers, testers, managers, etc) to develop a software system. UML is not tied to any specific methodology –

although it is often associated with specific approaches an processes.

UML Intro

4

System development activities ●

Requirements gathering

●

Requirements analysis

●

Design (to meet requirements)

●

Implement (to the design)

●

●

Test (make sure implementation meets requirements) Deploy (sell!).

UML Intro

5

The Waterfall Methodology ●

●

●

Each step is completed in detail for the entire system before moving to the next step.

Design Implementation

The goal is to cover every detail and consider all possibilities before design and implementation.

Test Deploy

For some types of activities this is necessary! ●

●

Requirements

Consider sending a man to the moon. Once the rocket has launched you can't decide to switch engine designs.

In general this model is not realistic for many type of software systems (won't lead to low-cost/high-quality). UML Intro

6

Iterative Approach ●

●

Entire cycle is repeated multiple times. –

it's not necessary to complete all steps each iteration.

–

Can start with base functionality (requirements) and build upon this incrementally.

General idea is to start with a coarse set of models, then iteratively refine and rework the models. –

The hope is that the process converges! UML Intro

7

Spiral Requirements Requirements

Test

Test

Design

Design

Design

Test

Requirements

Implement

Implement

Implement

UML Intro

8

UML and process ●

UML can be used to document each of the steps: –

requirements as use-case diagrams

–

design as OO models and structural models

–

Implementation (typically as OO, but doesn't need to be).

–

Tests

UML Intro

9

UML ●

●

Alphabet: symbols (drawing primitives) and strings. Words: grouping of elements from alphabet. –

smallest unit that has meaning

–

Two kinds: ●

Concepts –

●

drawn as rectangles

Relationships (between concepts) –

drawn as lines connecting two concepts that are related.

UML Intro

10

Sentences ●

A diagram that depicts the relationship(s) between some concepts is a UML sentence. Teach Teacher

Student

Evaluate Teacher

Student Ignore

Teacher ●

Student

Implied order when reading is left-to-right, topto-bottom UML Intro

11

UML and Objects ●

UML uses objects and classes to model concepts.

●

Relationships are called associations in UML.

●

A class is the definition of a type of object.

●

Student is a class –

Joe Smith could be an object of type Student

–

Usually shown as "Joe Smith:Student"

UML Intro

12

Attributes ●

Objects can have attributes –

●

the things the object knows

A class can include a list of attributes: Student Name RID Term Project Grade

UML Intro

class name

attribute names

13

Objects and attributes ●

For an object, each attribute can have a value. –

typically we only list the attributes relevant to the context of the diagram. Student

Name RID Term Project Grade

Joe Smith:Student Name = "Joe L. Smith" Term Project= E-Bay Clone

UML Intro

14

Classes and operations (methods) ●

●

A class can include a set of operations –

specification of what objects of the class can do

–

processing.

Keep in mind that UML classes are not tied to any implementation method –

●

we don't include code or even formal prototypes.

Keep in mind that the operations shown in any diagram are only those relevant to that diagram (to the context in which the class is displayed). UML Intro

15

Class Examples Teacher

name attributes

Give Lecture Assign project Induce Sleep Grade project

operations

UML Intro

Student Term Project Caffeine Intake Work on project Sleep

16

Example Diagram Student

Teacher

Caffeine Intake Prepare Lecture Induce Sleep

Sleep

Owns

Soda Machine

Needs

Location Price

UML Intro

17

Messages ●

Communication between classes is modeled as messages –

●

Communication between objects is called stimulus –

●

A message is a type of interaction between objects of specific classes.

an instance of a message between two objects.

A message models invocation of an operation. UML Intro

18

Stimulus ●

Sender object is called the client

●

Receiver object is called the supplier –

●

A single diagram can include many messages –

●

supplies the processing of the operation. the order is specified (it often is important!).

A messages (stimulus) is drawn as an arrow pointing from the sender to the receiver labeled with the message order and operation. UML Intro

19

Example 4: Wake Up

Teacher 1: Prepare

Student

2: Present

Lecture 3: Induce Sleep

UML Intro

20

Another Example 4: Wake Up

Dave:Teacher 1: Prepare

:Student

2: Present

UML:Lecture 3: Induce Sleep

UML Intro

21

Object Oriented Modeling Abstraction Encapsulation Generalization Polymorphism UML Intro

22

Abstraction ●

Both concepts and relationships

●

Reduce complexity

●

●

–

Only need to provide details of what is important to context.

–

ignore (or gloss over) details that are not important to the context.

Classes and Associations are general abstractions. Objects and Links are specific abstractions. UML Intro

23

Encapsulation ●

Combining attributes and operations into a single (abstract) entity. –

●

hides the details related to implementation

Information hiding –

Treat objects simply as entities with visible attributes and operations.

–

internal state/methods are not relevant outside of the object/class.

UML Intro

24

Generalization ●

●

Classes can be general (containing attributes and/or operations relevant to many types of concepts) A class can be specialized version of a general class (sometimes more than one general class). –

●

Inheritence

Define attributes and operations that are common to many classes in one general class. UML Intro

25

Generalization Example Person Name Address Email Sleep Wakeup Work

Student

Teacher

Term Project Grade

Soda Machine Office UML Intro

26

Polymorphism ●

Operations common to all specializations of a class allow us to refer to the operation universally. –

●

the actual methods (implementation) may be very different.

Polymorphism allows us to refer generically to an operation, knowing that the details of the operation depend on the specific type of object involved. UML Intro

27

Polymorphism Example Person Name Address Email

Any object that is of a class that is a kind of Person (a specialization of Person) has a Work method. We can consider the operation Work no matter what kind of Person object we have.

Sleep Wakeup Work

Student

Teacher

Term Project Grade

Soda Machine Office

Work

Work UML Intro

28

Exercise ●

●

Develop a UML diagram that describes a simple e-commerce system. Potential Concepts: –

User

–

Product

– –

Shopping Cart Shopping Cart Entry

●

●

Be as complete as you can. Include –

attributes

–

operations

–

associations

UML Intro

29