Object-Oriented Software Development - CiteSeerX

Object-Oriented Software Development

Jürgen Bö[email protected]://www.cs.umu.se/~jubo

http://www.cs.umu.se/kurser/TDBC31

OOSD--fall'04 Copyright © by [email protected] 2

Goals of the Course

Working in teamsIntroduction to object-oriented development

Iterative and incremental development processesObject-oriented techniquesWork product orientation

Introduction to real-life project issuesUsage of industrial-strength tools

This is NO programming courseWe do not teach any (OO) programmingWe assume you have sufficient programming skills


Project Issues

Teamwork (5-7 students)Complete life-cycle coverage“Real” customersSubcontractorsFuzzy and/or volatile requirementsMany deliverablesSeveral project presentationsFormal team meetingsFormal reporting routines


Project Examples

GamesSimulationsEditorsProject planningTrouble Reporting SystemVideo Manipulation...

See course home page for current proposals

Proposals will be presented in next lecture


Team Roles and Organisation

Each team has an (external) customer and a supervisorCustomer ≠ supervisor

Each team acts as a customer for an externally produced part of the systemFormal subcontract

Each team evaluates another team’s prototypeFeedback for development of final product


Teamwork

Team members take on specialist roles (e.g. team manager, requirements specialist, …)All team members must engage (at least) in OOA&D (in addition to role specific responsibilities)Individual diaries for project trackingRegular (formal) meetings to co-ordinate work

Team internalTeam managers with supervisors

Team decisions must be followed by all team membersAll team members are finally responsible for the overall project outcome


Specialist Roles

Team ManagerRequirements SpecialistUser Interface SpecialistDesign SpecialistCode Production Specialist

Quality Assurance SpecialistDocumentation SpecialistTools SpecialistWebmaster...

Please feel free to add further roles as neededWe recommend to have at least two individuals for each role


Specialist ResponsibilitiesResearch your jobIdentify your tasks and specific responsibilitiesEstimate the time to complete your tasksMonitor the completion of your tasksTrack your effort ( diary)Inform team members about the status of your workKeep yourself informed about project progressMaintain a list of problems / items to discuss

Be pro-active not re-activeKeep yourself informed on what is going on in the projectShow up in team meetings


Team Building

Students fill in a questionnairePersonal dataSkillsPreferences

Match and mix student skills and preferences to build equal teams

You need convincing arguments to change teams

OOPS! Some students will arrive lateTeams should maintain “job openings”


Effective Teamwork

Create clear goalsUnderstand each other’s expectations

Go for small winsSet attainable and concrete short term goals

Build mutual trustListen to each otherShow respectBe fair and objective

Ensure mutual accountabilityNo finger pointing

Help each otherSee web resources for more information.


Up-to-date, web-based project workbookWeekly reportsIndividual diariesDeliverables with firm deadlines

OOPS! Some deadlines might be negotiated

Project Documentation

Team descriptionProject managementRequirements document(G)UI designAnalysis/Design document

SubcontractPrototype user manualPrototype evaluationFinal report


Presentations

Team presentation, project plan, requirements, GUI mock-up, iteration planProject progress, OOA&D, prototype demonstration, revised iteration planProject summary, product presentation and demonstration, reflections, planned vs. actual work

All presentations should include actual project data

See course web pages for details


Grading

Individual grades (U, 3, 4, 5)Credit system:

Each team starts with 0 creditsFor each “performance” a team earns credits (quality x importance)

Quality on scale 0..6Importance on scale 1..15

For each deadline missed a team looses creditsCredits earned (adjusted by #team members) can be “freely” distributed among the team membersGrade is determined by the final number of credits

In case of problems/failure:Extra time for teams to complete projectsExtra assignments for individuals


Course Evolution 1

Criticism from earlier evaluationsWorkload too highToo little calendar timeUnclear grading systemToo much focus on deliverablesLectures not synchronised with deliverables

Major revision done for ht0210 credits instead of 5Two project iterationsSubcontracts are implemented by PVK teamsInternet university course


Course Evolution 2

Changes/improvements for ht02/03Product quality is evaluated and graded (twice)Lectures better synchronised with deliverablesMore detailed grading “rules”Revised descriptions of presentation and deliverablesReorganised web pagesMore formal individual diariesMore formal handling of change requests

Only small changes in contents since ht01, since students were quite satisfied


Course Evolution 3

Changes/improvements for ht04Three types of “products” (GUI mock-up, proof-of-concept prototype, fully functional product)More formal weekly reporting

Team managers meet weekly with supervisorsMore detailed description of weekly reports

Revised descriptions of deliverables and grading “rules”Student to team allocation no longer completely voluntaryPeer evaluations to enable early team trouble-shootingIntroduced signature blocks on deliverables


Organisational Details

Not all team activities are scheduled

Teams have to take initiativeOrganise internal team meetingsContact customers to gather project informationKeep all stakeholders informed about the projectLearn about necessary methods/tools/environmentsMake appointments with supervisors…

Your customers (and supervisors) are busy peopleMake appointments in good time


Obligatory Attendance

Lectures: At least 2 team members per team

Presentations:Your own team presents: All team members of your team must attendAnother team presents: At least 3 team members of your team must attend

Weekly Management Meetings: At least one team member per team (typically the team managers)

Work Load: On average you are expected to work about 20h/week (about 15 person months per team)


Tools--General

The usage of an approved UML tool is obligatoryYou can use other tools/languages/builders environments etc. as you like, if they seem appropriate for your team and/or project

HOWEVERYou get support only for the tools and environments we provide on our lab machines Problems due to the usage of “non-standard” tools/ environments are solely yoursMake sure your projects do not depend on such tools/ environments


Tools--RecommendationsUML diagramming

Together Control CenterVP-UMLThere are free versions of both for download

Team collaborationShared workspaces for distributed teamsSwiki.netBSCW (Basic Support for Cooperative Work)

Project ManagementMS Project(MrProject)

Version controlCVS

MiscProject workbook templateDocumentation from old courses


Contents

IntroductionObject-Oriented Software DevelopmentProject ManagementRequirements Gathering(G)UI DesignObject-Oriented Analysis and DesignAdvanced Topics in OOA&DImplementation and TestingReferences



What is Object-Oriented DevelopmentObject-Oriented vs. Traditional DevelopmentAn Object-Oriented Development FrameworkPhases, Activities, and Work Products


What is Object-Oriented Development “Object-oriented software construction is the software development method which bases the architecture of any software system on modules deduced from the types of objects it manipulates (rather than the function or functions that the system is intended to ensure).”

[Meyer 97]

A very brief history 1966: Object-oriented programming [Simula (Dahl and Nygaard)]

1982: Object-oriented design [with Ada (Booch)]

1988: Object-oriented analysis [OORA (Coad), OOSA (Shlaer and Mellor)]

1997: Unification of notations [UML V1.0 (Booch, Jacobson, Rumbaugh)]

1999: Unification of processes [RUP (Kruchten, Rational)]

2003: UML 2.0 [OMG]


func1(…)

Changing Views

Traditional viewOperations and data are separate entitiesData is globally visible

OO viewOperations + data = objects

func2(…)

func3(…)

...

A

B

C

...

A

func1(…) B

func2(…)

C

func2(…)

func3(…)

…

… …

…

…

…

……X


OO and the Semantic Gap

Hole

Ball

Club Border

Player Field

falls intohits

uses

rebounds

components

Semantic Gap


Important OO Concepts

ObjectEncapsulationMessage PassingClassesInheritancePolymorphism and Dynamic Binding(Multiple Inheritance)

See for example [Booch 94] or [Meyer 97] for details.


OO PhilosophyOO programs are systems of communicating objectsObjects have an internal state, behaviour, and identityClasses are templates for the creation of objects of the same typeSimilarities can be expressed by inheritanceBinding depends on the dynamic type of objects

ReadabilityExtensibilityMaintainability


The Context of (Object-Oriented) Development

Computing System

Problem Domain(“real world”)

Application Domain

User

Interaction

Solution( design model)

User perceptionof the real world

( analysis model)


Object-Oriented vs. Traditional Development☺Unified approach for analysis, design, and

implementation☺ Concepts in problem domain and solution are closer☺More “natural” concepts☺ Promotes encapsulation, extensibility, and reuse

Fuzzy borderline between analysis, design, and implementationMore difficult to manageMore complex component interrelationships

Transition problems



What is Object-Oriented DevelopmentObject-Oriented vs. Traditional DevelopmentAn Object-Oriented Development FrameworkPhases, Activities, and Work Products


An Object-Oriented Development Framework

Work product oriented and workbook centredFocus on the production of work productsHold and manage them in a central depository

Iterative and incrementalDivide the system into incrementsEvolve the system increment-wiseIteratively rework previous increments

Scenario-drivenModel externally visible system behaviour by scenarios/ use casesEnforce traceability through work products


The Project Workbook

A project workbook is a “logical document containing all the work products of a project.”

[OOTC 97, p 25]

A work product is a “concrete result of a planned project-related activity such as analysis or project management. Work products include items delivered to the customer and items used purely internally within a project.”

Seehttp://<course homepage>/Workbook/wb_template.html

for a project workbook template, orexamples from former groups

for actual examples.


Iterative and Incremental Development 1

Waterfall modelStrongly based on phasesStable documentsNo feedback/ rework

ProblemsIncomplete requirementsRework is necessaryNo early prototypes

SolutionDevelop a solution for growing subsets of requirements (increments)Rework existing solutions ( iterations)


Pre-iteration phaseGather initial requirements, plan project, start analysis

IterationsPlanning, Analysis, Design, Coding, Testing, Assessment

Plan incrementExecute planAssess quality

Post-iteration phaseSystem test, package, and ship


[P | A | D | C | T | A][P | A | D | C | T | A][P | A | D | C | T | A]



Requirements

[P | A | D | C | T | A]

[P | A | D | C | T | A]

[P | A | D | C | T | A]

Time

Iterations/increments

Increment 1Increment 2Increment 3


Typical Increments

Increment Purpose Activities

1 Get project started

Develop all planned work products for the Requirements Gathering and Project management phases. Review Analysis work products with customers. Concurrently, analysts, designers, and implementers develop guidelines for their phases. Designers can also start the System Architecture, Target Environment, and Subsystem Model work products.

2 Familiarise team with process and environment

Start with a few Use Cases and develop all planned work products for the Analysis, (G)UI, Design, and Implementation phases.

3..n-1 Complete project development

Taking a few Use Cases at a time, develop all work products for each phase through Implementation. As new work products are developed, old ones may need to be extended or amended.

n Package, test, and deliver the product

Implement the Physical Packing Plan and conduct the Installation, System, and Acceptance test plans.


Modelling and Software Development

Models make use ofAbstractionSeparation of concernsFamiliar and natural concepts

Models are tools toUnderstand a problem Cope with complexitySimplify problem solvingEnable traceability


Models Support Traceability

Real world Software system

Development

Model

X Y

X Y

☺ ☺


Examples of Models

In the real worldMapsFloor plansDiagrams…

In the computing sciences(Programming) Languages(Database) Conceptual modelsGraphs (for various purposes)…

Choose the right model for the right purpose


Models for (OO) Software Development

Use casesScenariosClass diagramsObject interaction diagramsState machinesFormal software specifications...


A Use Case for aCourse Registration System

Register for coursesDescription:This use case is initiated by the student. Itprovides the capability to create, review, modify,and delete a course schedule for a specializedsemester. All required billing information is sentto the Billing System.Actors:Student, Billing System.Notes:A student can register for at most 4 courses eachsemester....


A Use Case (cont.)

Register for coursesMain Flow of Events:1. The student enters the student ID number.2. The system verifies the ID number.3. The student selects a valid semester.4. The student creates, reviews, or changes a

schedule.5. The systems prints a notification.6. The system sends billing information to the

Billing System.


A Class Diagram

Person{abstract}

Studentcredits

Professor

namep_number

RegistrarregisterStudent()addCourse()

research_area


An Object Interaction Diagram

:RegistrarCourse Maintenance

Form tdbc18: Course

1: enter id2: verify id

3: create course

4: enter course info

5: submit6: create

7: save8: close form

time

add acourse


Coding

Test Case Development

ProblemStatement

Code Test Cases

ClassDescriptions

Requirements Gathering

Object-Oriented Analysis & Design

Implementation Testing

OO Development

???


Coding

Test Case Development

ProblemStatement

Code Test Cases

ClassDescriptions




Use Case Based OO Development

Use Case DevelopmentUse Case

Model

???


Coding

Elaboration

Assignmentof ResponsibilitiesOrganise

StateAbstraction

Consolidation

Test Case Development (white-box)

ProblemStatement

State Models

Code

Object Model

Test Cases

ClassDescriptions

Scenarios

Use CaseModel

ObjectInteraction Diagrams




Test CaseDevelopment

(black-box)

Scenario-Driven Development

Classifi

cation

Use Case Development

Traceability


Coding

Elaboration

Assignmentof ResponsibilitiesOrganise

StateAbstraction

Consolidation

Test Case Development (white-box)

LinguisticAnalysis

ProblemStatement

State Models

Code

Object Model

Test Cases

ClassDescriptions

Scenarios

Use CaseModel

ObjectInteraction Diagrams




Test CaseDevelopment

(black-box)

Work-Product Dependencies

Use Case Development

Classifi

cation


The Overall Development Process


UI Design

ImplementationPro

ject

Man

agem

ent

OOA&D

(System) Testing

(Re-)Planning

Initial Planning

feedback

harvest

adapt

Rep

osit

ory

(Wor

kboo

k)

QA

iterative and incremental development

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