UML – Universal Modeling Language

IT 210Introduction to Modeling

Modeling

Representing the world how it is—or how we want it to be

We can change the world for better, and we should

“Today the information highway, with all of its means of communication, affords an opportunity for us to carry the mission with a thousandfold greater speed and ease than Peter, James, and John and the other intrepid disciples.”

– President James E. Faust

Why Model?

Create, Design, Communicate Create: Generate ideas, solutions Design: Consistent, coherent

solutions (model) Communicate: Real world solutions

Abstract representation

Complete solution has many aspectsAbstract and generalizable

Specific:this_num = 1print this_numthis_num = 2 print this_num…this_num = 20print this_num

Abstract:

for num = 1 to MAX print numnext

Software modeling

Model process (sequence of activities)Changes of stateData structuresData structure types and with methods

Need languages of abstraction …

UML – Diagrams

Approaches to UML

SketchBlueprintProgramming

Ref: Martin Fowler, “UML Distilled”

UML Diagrams - Activity

Example Juke Box

Juke Box with Partitions

Also called swim-lanes

Source: CodeGear from Borland

UML diagrams - Sequence

Sequence – Juke Box

UML Diagrams - State

UML Goals

Provide users with a ready-to-use, expressive visual modeling language so they can develop and exchange meaningful models. Provide extensibility and specialization mechanisms to extend the core concepts. Be independent of particular programming languages and development processes. Provide a formal basis for understanding the modeling language. Encourage the growth of the OO tools market. Support higher-level development concepts such as collaborations, frameworks, patterns and components. Integrate best practices.

Review

The concepts on the following slides you should understand from CS 142.They are used in modeling.

Concept 1: Real world “thingy”

Entity, object, noun-verb Something that has a name Something that has Identity Person, place, thing Something you can point at. Something that does stuff or has stuff

done to it Can you think of another way to say it?

Entity/ObjectERM

Name

Attributes

Name

Attributes

Methods

UML

Concept 2: Instance/Class

Thingies are grouped by similar characteristics. “Person” is a class“Janet” is an instance

UML: Class/Instance

Person

Name:String Height:RealWeight:Real

Create(name:String,Height:Real,Weight:Real)

Delete()

Class Fred:Person

Name = Frederick G. Williams Height = 2.1Weight = 50

:Person

Name = Frederick G. Williams Height = 2.1Weight = 50

Named Person Instance

Anonymous Person Instance

Concept 3: Attribute

Characteristic of an object that defines a member of a class.

Concept 4: Property

Characteristic of an object that isn’t an attribute.For example: Height is an attribute of Person Location is not an attribute of the Person

object we defined.

Systems often “create” objects with attributes and “attach” properties.

Note: This is not standard terminology, but it matches most of what Microsoft does. No standard diagramming approach.

Concept 5: Relationship

Objects are related to each other in the real world. John husband of Mary Julio’s Ferrari Carburator part of engine Mary is a Girl

Some relationships are special enough to have their own names and diagrams

Concept 6: Value

Attributes can be assigned values.Properties can be assigned values.

Concept 7: Constraints

Attributes, Properties, and Relationships can be “constrained”. What constraints are possible is determined by the semantics of the value or Relationship. Height must be greater than 0 A man can have only one wife at a time.

Concept 8: Cardinality Constraints

You can count things.It is often important to constrain Cardinality of relationships: A person can only have one mother. A car can have only one VIN.

Cardinality

left right example

1 1 one-to-oneperson <-> weight

0..1 1optional on one side one-to-one

date of death <-> person

0..* or * 0..* or *optional on both sides many-to-many

person <-> book

1 1..* one-to-manyperson <-> language

Concept 9: Participation

Objects participate in relationships.Sometimes you want to constrain an object’s participation in a relationship. A “rental” object must have a car

Concept 10: Key

Something that identifies an object in a set of objects.Unique Key – no other object can have it.Composite Key – key made up of more than one attribute

Concept 11:Generalization

Employee is a person.An Employee object has all the characteristics of a person, and then some.

Concept 12: Specialization

Go the other way from Generalization. An object that has all of the attributes of a class, and then more attributes, is a member of the General class plus a class defined by all of the attributes.

Concept 13: Object/Entity

A thingy with identity, Attributes and Methods is called an object.Of course, all of the abstract class English words have been overloaded so many times you better ask what someone means before you “assume” anything.

Concept 14: Inheritance

A relationship between classes such that all of the attributes and methods of the super-class are projected into the sub-class. Two kinds Structure and Interface: difference beyond scope of lecture

Concept 15: Relationships with Attributes

Sometimes a relationship between two objects can have attributes. John was married to Mary on January

3, 2999 Marriage date is not an attribute of

either John or Mary. It is an attribute of their relationship.

Concept 16: System Modeling

This class is WEB SYSTEMS which includes data modeling, however, objects are more than just state. UML also models processing and many other attributes of a system.Data modeling is a part of what UML calls structure modeling.What the TA’s call a UML is an ACTIVITY diagram.