umldistilled

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© Martin Fowler 8/13/98

© Martin Fowler, 1998

Martin Fowler

[email protected]://ourworld.compuserve.com/homepages/Martin_Fowler

Page 2 © Martin Fowler 8/13/98

What We Will Cover (1)

q Background to UMLq Outline processq Grand Tour of Techniques

â Use Casesâ Class Diagramsâ CRC Cardsâ Both kinds of Interaction Diagramsâ Package Diagramsâ State Diagramsâ Activity Diagramsâ Design by Contract

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OO Methods

BoochBooch Rumbaugh / OMT

Rumbaugh / OMT

Jacobson / Objectory

Jacobson / Objectory

Odell / OOIEOdell / OOIE Shlaer / Mellor

Shlaer / Mellor

CoadCoad

Wirfs-Brock /RDD

Wirfs-Brock /RDDLate 80’s

early 90’s


Evolution of the UML

1988-92 Many analysis and design books1993 Standardization not a priority1994 Jim Rumbaugh joins Rational (Grady

Booch)1995 Booch/Rumbaugh unified method

released, Rational buys Objectory (IvarJacobson), OMG task force launched(chairs Mary Loomis and Jim Odell)

Jan 97 UML 1.0 submitted to OMG as proposalMid 97 OMG proposals unified behind UML 1.1Late 97 OMG adopts UML 1.1 as OMG UML 1.0Spr 98 OMG to issue UML 1.2 (minor changes)

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Unified Modeling Language (UML)

q Developed by the three amigos: Booch,Jacobson and Rumbaugh at Rationalâ Many contributions through OMG process

q Notation and semantics, not processq Organizations preparing processes

â Rational: Objectory (Unified Process)â HP: Fusion

Fowler M with Scott K, UML Distilled:Applying the Standard Object ModelingLanguage, Addison-Wesley, 1997

www.rational.com/uml


UML Books

q Three amigos booksâ User Guide, Reference, and Unified Processâ End 98

q Fowler: UML Distilled, Addison-Wesleyâ Concise guide, assumes you know OO design

q Larman: Applying UML and Patterns, PrenticeHallâ Intro to Objects using UML

q Martin and Odell, OO Methods a Foundation,Prentice Hallâ Conceptual Modeling

q Douglass, Real-Time UML, Addison-Wesleyâ Real Time

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Use-cases

q A use case is a typical interaction with thesystemâ Recognizable value to the user - meets a goalâ Testable

What would be some use cases for a WordProcessor?

http://members.aol.com/acockburn


Incremental Development

Cockburn A. Surviving Your Object-Oriented Project, Addison-Wesley, 1998

McConnell S. Rapid Development,Microsoft Press 1996

Goal: Reduce Risk

ExplorationDevelopment

1 2 ...

Finishing Finishing

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Development

q Break into incrementsâ Build a few use-casesâ Analysis, design, implementation, testing, and

integrationâ Demo to user and verify functional tests for those

use-casesâ Step length 2 weeks to 2 months

q Do high risk and high priority use-cases firstq Time box the steps

â Cannot slip dates, may put off use-cases

Goal: Have clear milestones to measure progress

Goal: Tackle high risks early


Explorationq Gather use-cases

â One or two paragraphs

q Outline conceptual modelâ Find key abstractions in conceptual problem

q Baseline technical architectureâ Try out key pieces of technology and how they fit

togetherâ Determine key packages and interfaces

q About 1/5 of project length

Goal: Gain understanding to reduce risks in laterdevelopment

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Dividing Use Cases

q Capture basic order informationâ Customer, date receivedâ Line items: quantity and product

q Price orderâ Rules vary with products, different price thresholds

and options.â May be combination rules

q Discount plansâ Customers may be members of various discount

plans.â Plans apply various discounts to ordersâ A particularly involved discount plan is the “bonnie

prince” plan

How many use cases here?


Granularity of Use Cases

Take Order

Take Order

Price Order

Customer Discounts

Bonnie PrinceDiscount Plan

Combination PricingRules

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The «extends» Notion

q Simple case and variations

Take Order

Price Order Customer Discounts

Bonnie PrinceDiscount Plan

Combination PricingRules

«extends» «extends»

«extends»«extends»


Use-case Diagram

q Shows use cases and links between themâ Actorsâ Uses and extends

q Can be useful but not essential

Trading Manager

Trader

Salesman

Set Limits

Analyze Risk

Price Deal

Capture Deal

Limits Exceeded

Valuation

«extends»

«uses»

«uses»

ActorUse Case

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Cockburn’s Style

q Base on the goal of a userq Consider main course scenario

â Everything goes well and goal succeedsâ Capture as sequence of steps

q Take each step in the use caseâ Ask what can go wrongâ Can we recover, if so howâ Each step may be another use case with its own

goal

q Capture variations in main courseq Note priority, time to be done in, and frequency

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Abuse Cases

q Decompositionâ Temptation to drive designâ Takes time (for little value)

q Abstractionâ Loses usersâ Less value in testing

q GUI prototypesâ False sign of progressâ Encourages scope growth

q Denying choiceâ System v user use cases

Have you seen these traps?

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Class Diagrams

Attributes

Operations

Association

Generalization

Class

OrderDate receivedisPrepaidNumberPrice

DispatchClose

Order Lineproductquantityprice

CustomerNameAddressCredit Rating

Corporate CustomerContact NameCredit RatingCredit LimitRemind

Personal CustomerCredit card #

]

]

1

1

{Orders for a customer with poorcredit rating must be prepaid}

Constraint


Modeling Perspectives

q Conceptualâ Describes people’s perception of the worldâ Independent of software

q Specificationâ Interfaces of classes (types)

q Implementationâ Internal features of a class

Cook, S. and Daniels, J. Designing Object Systems: object-oriented modeling with Syntropy, Prentice HallInternational, Hemel Hempstead, UK, 1994.

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Association

q Defines connections between instancesâ Conceptual: employees must have a single

departmentâ Specification: you can ask an employee object for

its department (and change it)â Implementation: employee has a pointer to a

department

q Uni-directional and bi-directional

notationfor cardinalities

Skill1Department[ [

[

An employee must have a single department

Employee


GeneralizationA nurse is a kind of a person

q Conceptual: all nurses are peopleq Specification: (subtyping) nurse satisfies the

interface of person (substitutable)q Implementation: nurse is a subclass of person

(inherits data and behavior)

Person

Doctor Nurse

At what stages would you use whichperspective?

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Dangers of Class Diagrams

q Emphasis on structure of classesâ May lead to data modelsâ De-emphasis on behaviorâ Lost in detailsâ Over-powerful abstractions

How can you tell when you have the rightmodel?


Class, Responsibility, Collaboration: CRC

q Developed by Ward Cunningham andKent Beck

q Informal techniqueq Concentrates on behavior, not data

OrderCheck Items are in StockDetermine the price Order LineCheck for valid payment CustomerDispatch to deliveryaddress

Order Line

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Interaction (Sequence) Diagrams

q Many objects in one use-case

an Order an Order Line a Stock Item

a ReorderItem

an Order Entrywindow

* prepare()hasStock :=

check()

[hasStock]remove()

prepare()

[needsReorder] new

needsReorder :=needsToReorder()

a DeliveryItem

[hasStock] new

Message

Iteration

Condition

selfdelegation

creation

return

Object

deletion


Interaction (Collaboration)Diagrams

q Numbering shows sequenceq Control symbols

â * For iterationâ [ ] For condition

:Order Entry Window

:Order

talisker line : Order Line talisker stock : Stock Item

: reorder item: Delivery Item

1:prepare()

1.1*[for all orderlines]: prepare ()

1.1.1: hasStock := check ()1.1.2:[hasStock] remove ()

1.1.2.1: needsReorder :=needToReorder ( )

1.1.2.2: [needsReorder] new1.1.3:[hasStock] new

Object

messagesequencenumber

selfdelegation

Which form would youuse?

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Key Books for Base Techniques

q Implementation focus: Booch, G. Object-oriented Analysis and Design WithApplications, (Second Edition), Benjamin /Cummings, Redwood City, CA, 1993.

q Conceptual Focus: Martin, J. And Odell, J.Object Oriented Methods: a Foundation, (UMLEdition) Prentice Hall, Englewood Cliffs, NJ,1998).

q For Responsibilities: Wirfs-brock R, WilkersonB and Wiener L (1990) Designing Object-oriented Software, Prentice Hall, EnglewoodCliffs NJ.


Patterns

q Patterns are the key to going beyond thebasics

q “Gang of Four” bookq Pattern Languages of Programming (PLoP)

conference

http://www.hillside.net/patterns

…projects fail despite the latesttechnology for lack of ordinarysolutions.

Ralph Johnson and Ward Cunningham

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Design Pattern: Proxy

q Provide a surrogate or placeholder for anotherobject to control access to it

Gamma, E., Helm, R., Johnson, R. and Vlissides, J. DesignPatterns: elements of reusable object-oriented software, Addison-Wesley, Reading, MA, 1995.

Real Subject

request()Proxy

request()

Subject

request()

realSubject.request()

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Analysis Patterns

q Prices of instruments change over timeq Hypothetical combinations of pricesq Prices of one instrument can affect others

Create a scenario to capture the real orhypothetical state of the market.

Instrument ScenarioElement

Scenario Timepoint

Money

[

1

1

1

1

[

[

[

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Packages

q Classes grouped into packages (categories)q Dependency (visibility) relationships

between packagesq Classes within package marked public or

private

Martin, R.C. DesigningObject-Oriented C++Applications Using theBooch Method, PrenticeHall, Englewood Cliffs,NJ, 1995.

StocksDatabase

Package

Dependency

StocksPricer

StocksPricer UI Portfolio UI

PortfolioApplication

PositionsScenarioManager

GUI Library


Harel Statechart

q Single object in many use-cases

Wait

Catch exit / hide lock

Lock

Open

entry / release killer rabbit

Final

H

Active

candle removed [door closed] door opened

catch released / reveal lock

key turned [candle out]

key turned [candle in]

close safe

H

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Simple Activity Diagram

q Similar to a flow chartReceive Order

Assign Goods toOrder

AuthorizePayment

Cancel Order

Dispatch Order

H

[suceeded]

[failed]


Decision Notation

q More similar to flowchart notationReceive Order


Cancel Order

Dispatch Order

H

[payment authorized]

[payment rejected]

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Introducing Parallel Behavior

q Sequence is independent

Receive Order


AuthorizePayment

Cancel Order

Dispatch Order

H

[failed]

[suceeded]


Adding Iteration

q Iteration also occurs in parallel

Receive Order

Assign Goods toItem

AuthorizePayment

Cancel Order

Dispatch Order

H

[failed]

*[for each line item]

[stock assigned to all items and payment authorized]

[suceeded]

Reorder Goods

[need to reorder]

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Multiple Diagrams (1)

q Order could be held up for stock

Receive Order

Assign Goods toItem

AuthorizePayment Cancel Order

Dispatch Order

H

[failed]



[suceeded]

Reorder Goods

[need to reorder]

Check Line Item

[in stock]


Multiple Diagrams (2)

q May also lead to dispatch order

ReceiveIncoming Goods

Chooseoutstandingorder items

Assign Goods toItem

*[for each chosen item]

[all chosen items assigned]

Add Remainderto Stock

H

Dispatch Order

[stock assigned to allitems and payment authorized]

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Combining Diagrams

Receive Order

Assign Goods toItem

AuthorizePayment

Cancel Order

Dispatch Order

H

[failed]



[suceeded]

Reorder Goods

[need to reorder]

Check Line Item

[in stock]

ReceiveIncoming Goods

Chooseoutstandingorder items

Assign Goods toItem

*[for eachchosen item]

[all chosenitemsassigned]

Add Remainderto Stock

H


Design by ContractSquare Root

q Inputsâ x : Real Number

q Outputâ result : Real Number

q Pre-conditionâ x 0

q Post-conditionâ result * result == x

q Exceptionsâ none

Meyer, B. Object-Oriented Software Construction,Prentice-Hall, New York, 1996

Meyer, B. “Applying “Design by Contract”,” IEEEComputer, 25,10, (1992), pp. 40–51.

www.eiffel.com

o Also uses classinvariants

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CASE Tools

Evaluate what you are getting

q Design Documentâ Drawing facilitiesâ Repository reportsâ Uses right set of UML for you?â Selectivity

q Code Generationâ Can you work with the code?â Updated code fed back into model?

What is your favorite CASE tool?


Translation

q Advocated by Shlaer/Mellorâ Basic idea also used by ObjectTime

4 Easy regeneration of system to differentplatforms

4 Can reuse the archetypes8 Does it work in practice?

Domain Analysis

Archetypes

Model Compiler Final System

Capturespecifics of

domain

Rules for yourplatform

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Why use these techniques?

q Start small, add notation as neededq Experiment with different things

â throw away what does not workâ different teams have different needs

q UML can communicate with programmers anddomain experts


A method is not enough

q Using a method will not make or break yourproject

q The choice of training and mentoring will makeor break your project

umldistilled

Technology

q fowler

martin fowler

uml q martin

usecases q

user q

fowler page

q shows

months q