UML 2selab.hanyang.ac.kr/courses/cse406/2017/lectures/06.UML.pdf · 2017-04-13 · UML 2.0 Introduction to UML 2.0 Model / View Paradigm Each UML diagram = a view of the system model

UML 2.0

UML 2.0

Scott Uk-Jin Lee

Division of Computer Science, College of ComputingHanyang University ERICA Campus

Scott Uk-Jin Lee CSE4006 Software Engineering

UML 2.0 Introduction to UML 2.0

UML

Unified Modeling Language

Visual language for specifying, constructing and documenting

Maintained by the OMG (Object Management Group)

http://www.omg.org

Model / View paradigm

Target language independent



Model / View Paradigm

Each UML diagram = a view of the system model

All diagrams together provides complete blueprint of thesystem



UML Diagrams



UML Usage

UML as :

Sketch

Selectivity (abstraction) is the keyno formal semantics are given

Blueprint

Completeness is the key

Programming language

to generate C/Java code from UML diagramsno formal definition exists of how the UML maps to anyparticular programming language


UML 2.0 Use Case Diagram

Use Case Diagram



Use Case

User Case is behavior or coherent set of behavior triggered byevents sent to the system

events are sent by human user(s), other systems, hardwarecomponents, internal clock

Use Case presents graphical overview on functionality providedby a system in terms of actors and their goals

Each Use Case specifies how to complete a goal or a task

Use Case treats the system as a black box and interactionswith the system are perceived as from outside the system



Use Case Diagrams

describe WHAT the system will do at a high-level



Actor

Someone or some thing that must interact with the systemunder development

Users, external systems, devices



an Actor is a Role

An actor defines a single role played by users in theirinteractions with the system:

multiple users can play a single rolea single user can play multiple roles



Identifying Actors

Primary Actor: Who will use the main functionality of thesystem ?

Who will need support from the system to their daily tasks ?

Secondary Actor: Who will need to maintain, administrate,and keep the system working?

Which hardware devices does the system need to handle?

With which other systems does the system need to interact?

Who or what has an interest in the results (the value) thatthe system produces?



Use Case

Functionality that the system shall offer to an actor

transaction among actors and the subjectinteraction between one or more actors and the system



Identifying Use Case

Which functions does the actor require from system?

Does the actor need to read, create, modify, or store somekind of information in the system?

Does the actor have to be notified about events in thesystem?

Could the actor’s daily work be simplified or made moreefficient through new functions in the system?



Subject Symbol

Indicate system boundary

Represent the system beinㅎ developedAll actors who interact with the system are outside of it



Association

Drawn between an actor and a use case

Represents bi-directional communication between the actorand the system



Dependency: Include

Represent relationship from a base to an inclusion use case

imply a Use Case calling another Use Caseto reuse behavior common to several Use Cases



Dependency: Extend

Used when additional behavior should be added

models optional or conditional behaviorshow infrequent events



Tips for Use Case Modeling

Make sure that each use case describes a significant chunk of systemusage that is understood by both domain experts and programmers

When defining use cases in text, use nouns and verbs accurately andconsistently to help objects and messages for interaction diagrams

Factor out common usages that are required by multiple use cases

If the usage is required use <<include>>If the base use case is complete and the usage may beoptional, consider use <<extend>>

A use case diagram should

contain only use cases at the same level of abstractioninclude only actors required

Large numbers of use cases should be organized into packages


UML 2.0 Class Diagram

Class Diagram



Class Diagrams

Description of static structureShowing the types of objects in a system and the relationshipsbetween them

Foundation for the other diagrams



Classes

Most important building block of any object-oriented system

Description of a set of objects

Abstraction of the entities

Existing in the problem/solution domain



Attributes & Operations

AttributesRepresent some property of the thing being modeledSyntax: attributeName : Type

OperationsImplement of a service requested from any object of the classSyntax: operationName(param1:type, param2:type, ...) : Result



Association & Multiplicity

AssociationRelationship between classes that specifies connections amongtheir instances

MultiplicityNumber of instances of one class related to ONE instance ofthe other class



Aggregation & Composition

Aggregation

Weak “whole-part” relationship between elementse.g., An airport has many airplanes

Composition

Strong “whole-part” relationship between elementse.g., Window ‘contains a’ scrollbar



Inheritance

Relationship between superclass and subclassesAll attributes and operations of the superclass are part of thesubclasses



Generalization & Specialization

GeneralizationBuilding a more general class from a set of specific classes

SpecializationCreating specialized classes base on a more general class



Active vs. Passive Class

Active classOwn a thread control and can initiate control activity- used when asynchronous communication is necessary- typically modeled with a state machine of its behavior- encapsulated with ports and interfaces

Passive classCreated as part of an action by another object- own address space, but not thread of control- executed under a control thread anchored in an active object



Ports vs. Interfaces

PortsDefine an interaction point on a classifier with externalenvironment

InterfacesDescribe behavior of objects without giving theirimplementation- each class implements the operations found in the interface



Stereotype in UML

UML extension mechanism

enables users to define the meaning of special modelingelementrepresented with double angle brackets



Provided & Required Interface

Provided interface

Class provides the services of the interface to outside callersWhat the object can doProvided interface accept incoming signal form outside callers

Required interface

Class uses to implement its internal behaviorWhat the object needs to doOutgoing signal are sent via required interface



Computer Device Example



Tips for Class Modeling

Finding Classes

Do we have things that should be stored or analyzed?

Do we have external system?- external system is modeled as class

Do we have any patterns, class libraries, components, etc?

Are there devices that the system must handle?

Make explicit traceability whenever possible

Try to capture classes/attributes from nouns of use-cases andoperations from verbs of use-cases

Always draw class diagram in conjunction with some form ofbehavioral diagrams


UML 2.0 Sequence Diagram

Sequence Diagram



Sequence Diagrams

Emphasize on the sequence of communications between parts

Show sequences of messages (“interactions”) betweeninstances in the system

Emphasize time ordering



Lifelines

Individual participant in the interaction over period timeSubsystem/ object/ classActorExternal system rolesin the interaction



Messages

Defines an expression of interaction fragments

May have parameters that convey values



Combined Fragment Frame

One-way communication between two objects

Interaction operators define how contents describe behaviorAlt: each section is one alternative (e.g., alt [a>0])Ref: reference to another Use CaseLoop: specifies a repeated sequence of behavior(e.g., ‘loop [1,5]’, ‘loop [6]’)



Referencing

Reuse already existing sequence diagrams

Avoid unnecessary duplication



Tips for Sequence Diagram

Set the context for the interaction

e.g., one use case

Express the flow from left to right and from top to bottom

Put active instances to the left/top and passive ones to theright/bottom

Draw sequence diagrams for each use-case if you want to lookat the behavior of several objects


UML 2.0 State Machine Diagram

State Machine Diagram



State Machine Diagram

Describe the dynamic behavior of objects over time bymodeling the lifecycles of objects of each class

The event that cause a transition from one state to another

The actions that result from a state change



State

State: condition or situation during the life of an object

Satisfies some condition, performs some activity or waits forsome event



Event & Action

Event

stimulus which causes the object to change state

Action

output of a signal or an operation call



Transition

Change state from one to another triggered by an event

Occur only when guard condition is true

Syntax: event(arguments)[condition]/action



Internal Activities

States can react to events without transition

putting the event, guard, and activity inside the state boxtwo special activities: the entry and exit activities

Internal activity is similar to self-transition

however, internal activities do not trigger the entry and exitactivities



Activity States

Regular activitiesinstantaneous behaviorcannot be interrupted

Do-activitiestakes finite timecan be interrupted

A normal state is quiet and waiting for the next event beforeit does something

Activity state is doing some on-going work



Superstates

Several states share common transitions and internal activities

move the shared behavior into a superstatea behavior can be expressed in a modular/hierarchical way


UML 2.0 Deployment Diagram

Deployment Diagram



Deployment Diagrams

Show runtime architecture of devices, execution environments,and artifacts in architecture

Physical description of system topology- Describe structure of hardware units and software executingon each unit



Deployment Diagrams

Node

computational resource upon which artifacts may be deployedfor execution

Communication path

show connection between nodesstereotype can be used for communication protocol or networkused

Artifact

specification of a physical piece of information that is used orproduced by a software development process, or by deploymentand operation of a system

e.g. model files, source files, scripts, and binary executable files, atable in a database system, a development deliverable, or aword-processing document, a mail message


UML 2.0 Summary

Summary

UML can be used as

sketch levelblue print levelprogramming language level

Use appropriate UML diagrams for different goals

when starting SE projects, start with- use-case diagrams with use-case texts

to look at behavior across many use cases or many threads- activity diagram

to look at behavior of several objects within a single use case- sequence diagram

to look at behavior of a single object across many use cases- state diagram


Documents

UML 2selab.hanyang.ac.kr/courses/cse406/2017/lectures/06.UML.pdf · 2017-04-13 · UML 2.0 Introduction to UML 2.0 Model / View Paradigm Each UML diagram = a view of the system model