Behavioral Modeling with UML 2.0Behavioral Modeling with UML 2.0

PowerPoint Presentation derived from Dennis, Wixom & Tegarden Systems Analysis and Design

John Wiley & Sons, Inc..and from

IBM/Rational Course on UML 2.0

Most slides Copyright 2001 © John Wiley & Sons. Others © IBM/Rational. Slide 1

Objectives• Understand the rules and style guidelines for

sequence and communication diagrams and behavioral state machines.

• Understand the processes used to create sequence and communication diagrams and behavioral state machines.

• Be able to create sequence and communication diagrams and behavioral state machines.

• Understand the relationship between the behavioral models and the structural and functional models.

Key Ideas

• Behavioral models describe the internal dynamic aspects of an information system that supports business processes in an organization

• Key UML behavioral models are: sequence diagrams, collaboration diagrams, and statechart diagrams

CONTEXT: UML DIAGRAMS

The Thirteen (13) UML 2.0 Diagrams

Class

ObjectComponent

Composite Structure

Deployment

Package

Structural Diagrams

Behavioral Diagrams

Use Case Activity

Interaction Overview

Sequence

State Machine

Timing

Communication

UML 2.0 DiagramsCoffeeMachine

CustomerMakeTea

TeaMaking

<<include>><<include>>

MakeCoffee

: Hardware: Controller: Customer

FromUser ::Coin (10)

FromUser ::Coin (10)

FromUser ::Coffee ()

FromUser ::Coffee ()

FillWater ()

FillWater ()

WaterOK ()

WaterOK ()

FillCoffee ()

FillCoffee ()

CoffeeOK ()

CoffeeOK ()

HeatWater ()

HeatWater ()

Warm ()

Warm ()

ToUser ::CupOfCoffee ()

ToUser ::CupOfCoffee ()

Sequence Diagram

Use Case Diagram

Interaction Overview Diagram

UML 2.0 Diagrams

Statechart Diagram

MakingCoffee

WaterOK

FillCoffee

WaterForCoffee

MakingCoffee

WaterForCoffee

WaterOK/̂ FillCoffee; Coffee/̂HeatWater;Coffee/̂HeatWater;

P1

FromUser

ToUser

Ctrl:Controller

P2P3

Hw:Hardware P4

WaterOK, Warm, CoffeeOK

FillWater, HeatWater, FillCoffee

FromUserToUser

CustbiCtrl

Architecture Diagram(Composite Structure)

CoffeeMachine

Customer

Controller

Hardware

CM

Cust

Ctrl

Hw

Class Diagram

UML 2.0 Diagrams

Activity Diagram Package Diagram

Component Diagram Deployment Diagram

When to Use Which Diagram?• UML is not a method or a

process, it is a visual language

• The different diagrams are like “tools” in a “tool-box”, each with a different intended use

Use Case Diagram

Use Case Diagram

StatechartDiagram

StatechartDiagram

Sequence Diagram

Sequence Diagram

Architecture Diagram

Architecture Diagram

ClassDiagram

ClassDiagram

CONTEXT: PROCESS MODELS

How Does UML Fit Into a Process?

• UML is the communication language used during the Analysis and Design Phases – aids communication between stakeholders and developers

• Using UML a complete, accurate and fully consistent description of the system can be created

• Using UML allows mistakes and errors to be easily identified. The process of looping through the system, removing errors is absolutely essential and unavoidable, and is described as iteration.

• Iteration occurs within all phases

The Waterfall Process• Divides the project into well-defined phases with intermediate

milestones• Each phase depends on the completion of the previous• The final product is not delivered until all phases are finished • Works best on small projects• Waterfall method has many advantages:

– it is the most direct way to the objective with the shortest development time and cost possible

• However, the drawbacks of this method include:– little flexibility for scope changes– system limitations not being discovered until later in

the development cycle– clients not being able to see the product until it is

completely finished

Analysis

Design

Implementation

Test

The Spiral Process• The spiral process is an iterative process

– Recognizes the need to visit requirements analysis/design/implementation/test sequence more than once

– Several reasons for this:• Identification and resolution of risks• Review of earlier “prototype” versions by the user to elicit

feedback. • Spiral model focus: to address

risks incrementally in order of priority

• Rounds follow the waterfall process

Analysis Design

Testing Implementation

The Iterative and Incremental Process

• A logical extension to the spiral model, but more formal and rigorous

• Structured in four phases: Inception, Elaboration, Construction and Transition

TransitionConstructionElaborationInception

Requirements Phase

ImplementationDesignAnalysisRequirements Test

Requirements Phase

Analysis Phase

ImplementationDesignRequirements TestAnalysis

Analysis Phase

Analysis Phase

• Understand the problem domain • Create a model describing the problem domain

– Free from any technical or implementation details– Detailed enough to allow simulation on paper or by using a

modeling tool• Activities:

– Acquire domain knowledge– Perform use case analysis– Define the necessary classes and relationships– Define the behavior and collaboration between classes– Test the resulting model

Analysis Phase

• Use Case Model with detailed use case descriptions– Natural language– Sequence diagram– Activity diagram– State Machine diagram

• Domain Model– Class diagram showing domain concepts and

their relationships

• System Interface Class Diagram– Interface Classes– Signals that compose the interfaces– Data types used by the signals

DeliverablesAnalysis Phase

When is the Analysis Phase Finished?

• When the Use Cases describe the functional aspects of the System to build

• When the Conceptual Model expresses the major components of the problem domain

• When the system interface is well defined• When developers feel comfortable estimating

the time it will take to develop each use case

Analysis Phase

BEHAVIORAL MODELS

Behavioral Models

• Systems have static &dynamic characteristics– Structural models describe the static aspects of

the system– Behavioral models describe the dynamics and

interactions of the system and its components

• Behavioral models describe how the classes described in the structural models interact in support of the use cases.

INTERACTION DIAGRAMS

Interaction Diagram Components

• Objectsan instantiation of a class

• Operationsthe behaviors of an instance of a class

• Messagesinformation sent to objects to tell them to execute

one of their behaviors

Kinds of Interaction Diagrams

• Sequence Diagrams• Communication Diagrams

Copyright 2001 © John Wiley & Sons, Inc. All rights reserved.

Slide 24

Sequence Diagrams• Model the behavior of use cases by describing

the way groups of objects interact to complete the task.

• Show sequences of messages (“interactions”) between instances in the system

• Each diagram depicts a possible set of messages only (a ”scenario”) – not all possible messages

• Are read left to right and descending • Emphasize time ordering

System Level Sequence Diagrams

• Describe the interaction between the Actors and the System– Remember: Black box

• Define the System Interface• Can be used as System Level Test Cases

Slide 26

Sequence Diagram Syntax

Sequence Diagram – elements

Lifeline

Associated Use Case

Use Case Reference

Message line

Message name

Analysis Phase

OrderCoffee

OrderCoffee - Basic

TAU specific

The interaction name and page numbering is Tau specific

Lifelines• A Lifeline consists of a rectangle that identifies the

connectable element (such as a part or component) and a vertical line indicating its time of existence

Lifeline of unknown Class

Lifeline of an Anonymous Object

Lifeline of an Object of a known class

Analysis Phase

More Sequence Diagram Syntax

Sample Sequence Diagram

Object Communication• Messages are labeled with the name of the message

(operation or signal) and its argument values.• Message parameters can be a data type, a variable or a

constant.• For correctness the variables and constants must be declared• To make the interaction more general use data types or

variables as parameters

Analysis Phase

Data type

Variable

Value

Referencing• To avoid unnecessary duplication it is possible to reuse

already existing Sequence Diagrams• The name is the Use Case name, not the Sequence

Diagram name. – A Use Case encapsulates zero or more Sequence, or other

types of diagrams

Analysis Phase

Steps to Build Sequence Diagrams(Dennis)

1. Set the context2. Identify which objects will participate3. Set the lifeline for each object4. Lay out the messages from top to bottom of the

diagram based on the order in which they are sent5. Add execution occurrence to each object‘s lifeline6. Validate the sequence diagram

Steps to System Level Sequence Diagrams(alternate view)

1. Select a Use Case to model2. Select a scenario:

– Basic: positive and straightforward behavior– Alternative– Exception

3. Add lifelines for the System and each involved Actor4. Add interactions between the Actors and the System

using arrows5. Name the arrows using message names and

parameters– Keep it simple, no need to provide all parameters at this

point

Analysis Phase

Sequence Diagram Guidelines• Keep the diagram simple

– If it is too complex, perhaps it should be broken down into separate diagrams

• Don’t capture all the scenarios in one diagram– One diagram per scenario

Analysis Phase

INTERACTION OVERVIEW DIAGRAMS

Slide 37

Interaction Overview Diagrams• A specialized activity diagram that shows how

sequence diagrams can be put together• Allow you to construct a “roadmap” of sequence

diagrams and navigate easily among them

Analysis Phase

Interaction Overview Diagram Guidelines

• Keep the diagram simple– If it is too complex, perhaps it should be broken

down into separate diagrams

• Show how different Sequence Diagrams interconnect with each other

Analysis Phase

COMMUNICATION DIAGRAMS

What Is a Communication Diagram?• A communication diagram emphasizes the

organization of the objects that participate in an interaction.

• The communication diagram shows:– The objects participating in the interaction.– Links between the objects.– Messages passed between the objects.

Communication Diagrams

Example: Communication Diagram

: Student

: RegisterForCoursesForm

: RegistrationController : CourseCatalogSystem

5: display course offerings( )6: display blank schedule( )

: Course Catalog1: create schedule( )

2: get course offerings( )

3: get course offerings(forSemester)

4: get course offerings( )

Communication Diagrams Contents: Objects

Objects

: RegisterForCoursesForm

: RegistrationController SWTSU Catalog : CourseCatalogSystem

Communication Diagram Contents: Actors

: Student : Course Catalog

: RegisterForCoursesForm

: RegistrationController SWTSU Catalog : CourseCatalogSystem

Actors

Communication Diagram Contents: Links and Messages

: Student

: RegisterForCoursesForm

: RegistrationController : CourseCatalogSystem

5: display course offerings( )

6: display blank schedule( )

: Course Catalog1: create schedule( )

2: get course offerings( )

3: get course offerings(forSemester)

4: get course offerings( )

Links

Messages

Sequence and Communication Diagram Similarities

• Semantically equivalent– Can convert one diagram to the other without

losing any information

• Model the dynamic aspects of a system• Model a use-case scenario

Sequence and Communication Diagram Differences

Sequence diagrams

Communication diagrams

Show the explicit sequence of messages

Show execution occurrence

Better for visualizing overall flow

Better for real-time specifications and for complex scenarios

Show relationships in addition to interactions

Better for visualizing patterns of communication

Better for visualizing all of the effects on a given object

Easier to use for brainstorming sessions

ACTIVITY DIAGRAMS

Activity Diagrams

• Activity diagrams describe the workflow behavior of a system

• Activity diagrams can show activities that are conditional or parallel.

• Activity Diagrams are useful for: – analyzing a use case by describing what actions need

to take place and when they should occur – describing a complicated sequential algorithm– modeling applications with parallel processes– modeling bussiness workflow

Analysis Phase

Activity Diagram - elementsAnalysis Phase

Fork Join

Decision Node

Object Node

Action Node

Initial Node

Activity Final

Guard

Activity Diagram Symbols - 1Initial nodeStarting point for invocing other activities. An activity may have several starting points.

Action/ActivityAn action is an executable unit. Can also refer to a new activity diagram.

Activity2

if (a) { x = 7; }

Analysis Phase

Action States and Activity States

• Each state in an activity diagrams is either:– an action state

• describes an atomic action• the outgoing transitions are implicitly triggered by the

completion of the action in the state– or an activity state

• describes an enduring activity which can be interrupted• invokes an activity graph• the activity state is not exited until the final state of the

nested graph is reached.

Analysis Phase

Activity Diagram Symbols - 2

Class3

Object nodeRepresents an instance of a clasifier, usually a classUsed to show input to or output from an action.An object flow shows objects being generated or used by actions or activities in activity diagrams

Analysis Phase

UpdateOrder

UpdateOrder

CustomerOrderCustomerOrder

PrepareInvoice

PrepareInvoice

Activity Diagram Symbols - 3Decision nodeA decision node is a control node that chooses between outgoing flows.Each branch has its own guard condition“Else” may be defined for at most one outgoing transition

x

Fork/Join symbolDivides a flow into multiple concurrent flows. Flows can be split and synchronized again.

Analysis Phase

Activity Diagram Symbols - 4

Connector symbolLabel and Join

Signal12

Accept event symbolRepresents an input action.

Send signal symbolRepresents an output action.

Accept time event symbolRepresents a timeout situation. To set a timer, use textual syntax in an action node

Analysis Phase

Activity Diagram Symbols - 5Activity final symbolAborts all flows in the containing activity.

Flow final symbolDestroys all tokens that arrive at it, but has no effect on other flows.

Integer i; Text symbol

Comment symbol: • unconnected or unselected it looks almost like a text symbol.

Analysis Phase

//MyComment

Activity Diagram Symbols - 6SL1

Activity Partition (Swim lanes)Swim lanes visually group the action states. They have no semantics but are often used to show a relation between activities, for example activities performed by a person, business unit etc.Swimlanes can also contain other swimlanes. You can also indicate that a swimlane represents a certain part or that it represents an external entity.SL3

SL3

SL2

SL2

SL1c3:Class3

<<external>>

SL1c3:Class3

<<external>>

Analysis Phase

Activity Diagram – Swimlane Example

• Transitions can take place from one swim lane to another

Analysis Phase

AccountList

ControlUnit

Customer

'Prompt For Card'

[Display("Insert Card")]

[Display("Insert Card")]

'Customer Inserts Card'

Card

'Prompt for Pin'

[Display("Enter Pin")]

[Display("Enter Pin")]

'Customer Provides Pin'

ValidateCardandPin

Pin

CardInfo

ValidateCardInfo

Activity Diagram – Example

Card Inserted

System promptsfor PIN

Customerenters PIN

Log invalid PIN

Validate PIN

Selecttransaction type

Prompt PIN invalid

[PIN invalid][PIN valid]

Reject card

[NbrOfAttempts < 3]

System promptsfor amount

System promptsfor currency

[Withdrawal] [Foreign currencytransaction]

Customer entersamount

Customerenters currency

Analysis Phase

Guard: Follow this path, only if the text in the brackets [ ] evaluates to true.

Activity Diagram Guidelines• Keep the diagram simple

– The focus is easy communication. Don’t be too formal• Swimlanes should only represent the Actors and the

System• All required Object Nodes should be part of the Conceptual

Model– Revise the Model if necessary

• Try to capture all the scenarios of the Use Case in one diagram– But be careful not to overload the diagram. If necessary use

more than one per Use Case• Emphasize the collaborative and parallel aspects of the

behavior

Analysis Phase

Drawing Activity Diagram• Remember, this is an iterative process• Select a Use Case to model• Look at all scenarios:

– Basic: positive and straightforward behavior– Alternative– Exception

• Find the Use Case participants• Find the main activities

– Internal and Intermediate activities will be defined in later phases• Find the Decision Criteria that defines the transition between

activities• Find the Input and the Output for the activities• Determine which activities are parallel/concurrent and which ones

are sequential

Analysis Phase

Exercise 8

Assignment Build Activity Diagram• Identify the participating candidates and draw the

associated swim lane

• Identify and define activities

• Identify and define transitions between those activities

• Add the necessary decision nodes that are necessary to understand the use case

• If pertinent, add the Object Nodes and Flows

Analysis Phase

BEHAVIORAL STATE MACHINES

State Machine Diagram

• A state machine diagram specifies the dynamic behavior of an element in a reactive, event-driven way

• Specifies a finite number of states of an element and how transitions between states are performed in response to events

• Typically not used for all objects– Just for complex ones

Analysis Phase

State Machine Diagram Usage

• To elaborate use case specifications• To specify high-level system behavior during

analysis• Capture significant events that can act on an

object

Analysis Phase

System Level State Machine Diagram

• Defining a System Level State Machine that includes all Use Cases would be unrealistic– Too many system states– Too many possible transitions

• Instead, a System Level State Machine should be created to show only some aspects of the functionality

• Each of these State Machines could be used to do partial simulation of the System– On paper– Using a UML tool

Analysis Phase

Components of State Machines

• Statesvalues of an object’s attributes at a point in time

• Eventschange the values of the object’s attributes

• Transitionsmovement of an object from one state to another

• Actionsatomic, non-decomposable processes

• Activitiesnon-atomic, decomposable processes

State Machine Syntax

State Machine Diagram - elements

Initialstate

State

Self transition

Transition

Finalstate

Analysis Phase

Sample State Machine

Transition (1)event-name ( parameter-list ) [ guard-condition] / action-expression;

Guard-condition

Event-name

Action-expression

Parameter-list

Analysis Phase

TAU specific

The action language in transitions is Tau specific

incoming-signal-name / signal-output;Warm / ^FillWater;

incoming-signal-name ( parameter-list ) / operation-call;Coin(faceValue) / Amount = AddCoin

( Amount , faceValue );The variable that will contain the parameter

value, must be declared and visible within the scope of the state machine

Transition (2)event-name ( parameter-list ) [ guard-condition] / action-expression;

Analysis Phase

Transition (3)event-name ( parameter-list ) [ guard-condition] / action-expression;

[ guard-condition] / signal-output ( parameters-list ); [Amount >= drinkCost] /

^theMessage(“Please make your drink selection”);

incoming-signal-name [guard-condition] / signal-output;Tea [Amount < drinkCost] / ^GetTeaBag;

Analysis Phase

Steps to Build a State Machine

1. Set the context2. Identify the initial, final, and stable states of

the object3. Determine the order in which the object will

pass through the stable states4. Identify the events, actions, and guard

conditions associated with the transitions5. Validate the behavioral state machine

State Machine Diagram Guidelines• Keep the diagram simple

– If it is too complex, perhaps it should be broken down into separate diagrams

• Try to capture all the scenarios of a Use Case in one diagram– One diagram per Use Case

Analysis Phase

Drawing State Machine Diagrams• Find the Classes or Use Cases that are important enough to

justify a behavior analysis • Find the main states

– Internal and Intermediate states will be defined later in the Design phase

• Find the required transitions to fulfill all the Actors’ requests

• As for the Sequence Diagram, name the incoming request and answers in a natural language. Message names will be defined/refined later.

• Do not define sub-state machine– Keep it simple– Simply give the short description of the internal state behavior

Analysis Phase

CRUD ANALYSIS

CRUD Analysis• Labels object interaction in 4 possible ways

– Create– Read– Update– Delete

• Matrix representation of objects and interactions• Most useful as a system-wide representation

– Identify complex objects– Catch omissions– Group closely related classes

Sample CRUD Matrix