A Framework, Methodology and Tool for Reusable Software Components

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A Framework, Methodology and Tool A Framework, Methodology and Tool for Reusable Software Componentsfor Reusable Software Components

Prof. Steven A. DemurjianComputer Science & Engineering Department

The University of Connecticut191 Auditorium Road, Box U-155

Storrs, CT 06269-3155

[email protected]://www.engr.uconn.edu/

~steve(860) 486 - 4818

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MotivationMotivation

Reuse Afterthought in OO Design/DevelopmentReuse Afterthought in OO Design/Development Majority of Reuse Focuses on “Small” Majority of Reuse Focuses on “Small”

ComponentsComponents String Functions, Utility Routines, GUI, etc. Easy to Understand - Easy to Reuse Minimal Savings

Three Classes of Software Three Classes of Software Domain-Independent (20%) : Libraries,

Utilities, etc. Most Likely to Be Reused Domain-Specific (65%) : Dedicated Software

Reused in Other Programs of Same Domain Application-Specific (15%): Uniqueness

Unlikely to Be Reused

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MotivationMotivation

Popular OO Design Methodologies Omit and Popular OO Design Methodologies Omit and Ignore Reuse GuidelinesIgnore Reuse Guidelines OMT and UML Design Patterns

Current Research Concentrates on Current Research Concentrates on ConsumerConsumer (Reuser) and Not (Reuser) and Not ProducerProducer (Creator) (Creator) Measure Savings from Reuse Calculate Return on Investment

Two-Fold GoalTwo-Fold Goal Elevate Reuse to Equal Partner Starting with

Design Focus on Domain-and-Organization Specific

Reuse

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MotivationMotivationWhy Software Reuse?Why Software Reuse?

Increase Software Productivity Increase Software Productivity Shorten Software Development Time Shorten Software Development Time Improve Software System Interoperability Improve Software System Interoperability Develop Software With Fewer People Develop Software With Fewer People Move Personnel More Easily From Project to Move Personnel More Easily From Project to

Project Project Reduce Software Development and Maintenance Reduce Software Development and Maintenance

Costs Costs Produce More Standardized Software Produce More Standardized Software Produce Better Quality Software Produce Better Quality Software Provide a Powerful Competitive AdvantageProvide a Powerful Competitive Advantage

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Overview of PresentationOverview of Presentation

Cultural and Social Reuse IssuesCultural and Social Reuse Issues Component-Based Design - History & PerspectiveComponent-Based Design - History & Perspective Reuse Framework, Methodology, and ToolReuse Framework, Methodology, and Tool

Subjective Identification of Components General vs. Specific Classes Related Hierarchies to Quantify Components

Objective Measure of Dependencies Classifying Dependencies Measuring Reuse Potential

Reuse Guidelines Methodological Basis for Increasing Reuse Iterative Improvement in Reusability

Evaluation and Analysis: DRE Tool/Examples Conclusions and Future ResearchConclusions and Future Research

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Cultural and Social Reuse IssuesCultural and Social Reuse IssuesManagement SupportManagement Support

Motorola Study: A New Reuse Program there must Motorola Study: A New Reuse Program there must have Strong/Unequivocal Management Supporthave Strong/Unequivocal Management Support

Raytheon Report: Support from Upper Raytheon Report: Support from Upper Management Most Important for Successful ReuseManagement Most Important for Successful Reuse

Why? IncreasedWhy? Increased Cost Associated with Constructing Reusable

Components Communication, Coordination Education, Training

Motorola and Raytheon Facilitate by IncentivesMotorola and Raytheon Facilitate by Incentives Both Producer and Consumer Benefits Awards Provided for Demonstrated Efforts

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Recall the Different AbstractionsRecall the Different Abstractions

Classes and HierarchiesClasses and Hierarchies Building Blocks of

Application Independent Classes

of All Types Generalization and

Specialization InterfacesInterfaces

“Specification” of Behavior

Never Instantiated

PackagesPackages Organize Classes and/or

Hierarchies into Named Conceptual Units

ComponentsComponents Application-Oriented Logical and Physical

Associations of Interfaces, Classes, Packages

Purpose: Represent a “Meaningful” Chunk of Functionality

This is a Design Time Component (e.g., a Non-Instantiated Bean)!

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Components vs. ObjectsComponents vs. Objects

ComponentsComponents

Business Oriented Coarse Grained Standards Based Multiple Interfaces Provide Services Fully Encapsulated Understood by

Everyone

ObjectsObjects Technology-Oriented Fine Grained Language Based Single Interface Provide Operations Use Inheritance Understood by

Developers

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Reusable Components Reusable Components Types & BenefitsTypes & Benefits

Application Template Application Template Data Model Data Model Data Structure Data Structure System Architecture System Architecture Process Model Process Model Process Definition Process Definition Prototype Prototype Plan Skeleton Plan Skeleton User Interface User Interface

Skeleton/GUISkeleton/GUI Process SkeletonProcess Skeleton Utility ComponentsUtility Components

Organizational Organizational PerspectivePerspective Shorten Development

Time Reduce Costs Increase

Competitiveness Personnel PerspectivePersonnel Perspective

Increase Productivity Customer Perspective Customer Perspective

Achieve Greater User Satisfaction Through the Production of More Flexible Products

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Component-Based Development ProcessComponent-Based Development Process

TOP-DOWN:To determine what is needed to satisfy this need.

BOTTOM-UP:To determine what is available to satisfy this need.

OTHERS:Consider the similarity among concurrent projects.

FUTURE:Consider the possibility of reusing in future projects.

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Supplier /Consumer ModelSupplier /Consumer Model

SUPPLY Build New Wrap Existing Buy

CONSUME Assemble Applications

MANAGE Publish Subscribe Catalog Browse

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Component-Based Tools/Web Sites of NoteComponent-Based Tools/Web Sites of Note

Software Software Composition Composition WorkbenchWorkbench

JavaBeansJavaBeans Visual CaféVisual Café Visual J++Visual J++ Sun’s ForteSun’s Forte Enabler, SoftlabEnabler, Softlab Microsoft Microsoft

RepositoryRepository UREP, UnisysUREP, Unisys Select Software Select Software

Tools, SelectTools, Select

Reusable Software Research Group, Reusable Software Research Group, West Virginia University West Virginia University http://www.csee.wvu.edu/~resolve/scw/

rsrg-brochure-nov-98.html Reusable Software Research Group, Reusable Software Research Group,

Ohio State UniversityOhio State University http://www.cis.ohio-state.edu/rsrg/

index.html Select Software ToolsSelect Software Tools

http://www.selectst.com/ Software Reuse Executive Primer, Software Reuse Executive Primer,

DODDOD http://dii-sw.ncr.disa.mil/ReuseIC/pol-

hist/primer/ Model-Driven Software Reuse, Model-Driven Software Reuse,

Extended Intelligence Inc.Extended Intelligence Inc.

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A Framework, Methodology, and Tool for A Framework, Methodology, and Tool for Reusable Software ComponentsReusable Software Components

Reuse as Equal Partner Starting with DesignReuse as Equal Partner Starting with Design Iterative Reusability Evaluations at Early and

All Stages of Design and Development Production of Large Reusable Components

Capabilities of Evaluation TechniquesCapabilities of Evaluation Techniques Identify the Reusable Portions of Design Estimate/Measure Reusability Automatically Provide Guidelines on Improving Reusability Usable for

Newly Created Designs Evaluation of Legacy Code for Reuse Potential

Integrated in UML Design Environment (Together CC) and Independent Tool

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A Framework, Methodology, and Tool for A Framework, Methodology, and Tool for Reusable Software ComponentsReusable Software Components

1. Define Components, Their 1. Define Components, Their Interactions, and Analyze Interactions, and Analyze Their ReusabilityTheir Reusability

2. Store an Iteration of Design2. Store an Iteration of Design3. Implement an Iteration3. Implement an Iteration4. Store and Document 4. Store and Document

Iteration of ImplemenIteration of Implemen..5. Reevaluate an Existing 5. Reevaluate an Existing

Design forDesign for Correcting Errors New Reuse Potential

6. Reuse Existing Design with 6. Reuse Existing Design with a New Implementationa New Implementation

Store &DocumentDesigns

ReusabilityEvaluation

Implementthe System

Re(Design)a System

Store &DocumentImplemens.

11

55

44

66 33

22

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Subjective IdentificationSubjective Identification ofof ComponentComponentss

Reuse Historically Occurs at Class LevelReuse Historically Occurs at Class Level Class as “Atomic” Component only Scratches Class as “Atomic” Component only Scratches

Surface in Reuse Potential for OOSurface in Reuse Potential for OO But, Classes InteractBut, Classes Interact

If Reuse One, Often Need Others Thus, Reuse Set of Classes

Expand Reuse from Class to Component LevelExpand Reuse from Class to Component Level Establish Framework for Promoting Design ReuseEstablish Framework for Promoting Design Reuse

Characterize General vs. Specific Classes Quantify Related Components Illustrate via HTSS and Financial Frame

Applications Goal: Increase Reuse Potential by Understanding Goal: Increase Reuse Potential by Understanding

Classes, Components, and their Role within Appl.Classes, Components, and their Role within Appl.

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General/Specific ClassGeneral/Specific Class CharacterizationCharacterization

Subjective Characterization by Software DesignerSubjective Characterization by Software Designer Best Estimate on Potential Utility of ClassBest Estimate on Potential Utility of Class General Class (G)General Class (G)

Those Application Classes that Facilitate Domain-and-Organization Specific Reuse

Specific Class (S)Specific Class (S) Those Application Classes that are Limited to

use in a Single Application PurposesPurposes

Determine Classes with Highest Reuse Potential for Organization’s Future Systems

Dependencies from General to Specific are both Non-Reusable and Hinder Reuse

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General/Specific ClassGeneral/Specific Class CharacterizationCharacterization

General Class (G)General Class (G) Expected to be Reused in Future Applications Abstract Classes/Root Classes/Non-Leaf

Classes in Inheritance Hierarchies Domain Independent/Domain Specific What are Some Examples?

Specific Class (S)Specific Class (S) Only Applicable in Current Applications Unlikely to be Reused in Future Applications Classes that Retrieve from Company Database Application Specific What are Some Examples?

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High-Tech Supermarket System (HTSS)High-Tech Supermarket System (HTSS)

Automate the Functions and ActionsAutomate the Functions and Actions Cashiers and Inventory Updates User Friendly Grocery Item Locator Fast-Track Deli Orderer Inventory Control

User System Interfaces User System Interfaces Cash Register/UPC Scanner GUI for Inventory Control Shopper Interfaces Locator and Orderer Deli Interface for Deli Workers

We’ll Introduce and Utilize Throughout Lecture

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The HTSS Software ArchitectureThe HTSS Software Architecture

ICICICIC

CRCRCRCR

CRCR

CRCR

ILILILIL

ILIL

SDOSDO

SDOSDO EDOEDO

EDOEDO

OrderOrder

PaymentPayment

ItemItemItemDBItemDBLocalLocalServerServer

Non-LocalClient Int.

InventoryInventoryControlControl

ItemDBItemDBGlobalGlobalServerServer

OrderDBOrderDB

SupplierDBSupplierDB

CreditCardDBCreditCardDB

ATM-BanKDBATM-BanKDB

IL: Item IL: Item LocatorLocator

CR: Cash RegisterCR: Cash RegisterIC: Invent. ControlIC: Invent. Control

DO: Deli Orderer forDO: Deli Orderer for Shopper/EmployeeShopper/Employee

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A General Class in HTSSA General Class in HTSS

Why is Why is ItemItem General? General? What is Applicability of What is Applicability of ItemItem??

class Item { private: // Private Data int UPC; char* Name; int InStock, OnShelf, ROLimit; float RetailCost; public: // Public Methods Item(int code, char* str, int st1, int st2, int st3, float cost); void CreateNewItem(); int GetUPC(); char* GetName(); int GetQuantity(); int CheckReorderStatus(); void PrintItem(); void UpdatePrice(float new_value); };

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Another General Class in HTSSAnother General Class in HTSS

Collection Classes of General Classes are General Collection Classes of General Classes are General

class ItemDB {private: int Num_Items; int Curr_Item; Item* AllItems[Max_Items];

int FindFirstItem(); int FindNextItem(); int FindItemUPC(int code); int FindItemName(char* name); public: ItemDB(); // Constructor void InsertNewItem(Item* new_one); void DeleteExistingItem(int code); void FindDisplayItemUPC(int code); void FindDisplayItemName(char* name); void PrintAllItems(); };

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Yet Another General Class in HTSSYet Another General Class in HTSS

GUI-Based Class for Supporting Inventory GUI-Based Class for Supporting Inventory Control Actions Can be Domain IndependentControl Actions Can be Domain Independent

class InvControlGUI { private: int Curr_Option; // Current menu option public: InvControl(); // Constructor void PrintMenuSetOption(); void ActivateController(); void EnterNewItem(); void RemoveExistingItem(); void FindItem(); void InvSearchQuantity(); void InvSearchReorder(); void GenerateAnOrder();};

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Specific Classes in HTSSSpecific Classes in HTSS

General Classes are Refined to Represent General Classes are Refined to Represent Particular Items, Yielding Specific ClassesParticular Items, Yielding Specific Classes

...

Item

DairyItemProduceItem DeliItem

DeliOrdererGUI

OrdererGUI

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Levels of General ClassesLevels of General Classes

Not All General Classes Created EquallyNot All General Classes Created Equally Level of Generality Based on Role in ApplicationLevel of Generality Based on Role in Application

PurposesPurposes Accommodate Large Systems with Multiple,

Different Reusable Components Reusable Components can Overlap, but Still be

Distinct Reusable Units

S,...,G,G,G 2100G

2G0G 0G

1G

2G SS

SS1G

views as General if i j views as Specific if i < j

iG jG

jGiG

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...

Can we Identify Different Levels Can we Identify Different Levels of General Classes?of General Classes?

DairyItem DeliItem

Item

ProduceItem

NonPerishItem PerishItem

)(G0

)(G1 )(G1

)(G2)(G2

BigYProdItem DoleProdItem BigYDairyItem HoodDairyItem

Where can ItemWhere can Itembe Reused?be Reused? Where can Where can

NonPerishItem NonPerishItem and PerishItemand PerishItembe Reused?be Reused?

Where can ProduceItem and Where can ProduceItem and DairyItem be Reused?DairyItem be Reused?

Are DoleProdItem and HoodDairyItem Specific?Are DoleProdItem and HoodDairyItem Specific?

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General/Specific Paradigm in HTSSGeneral/Specific Paradigm in HTSS

Abstraction from Abstraction from HTSSHTSS to to Domain IndependentDomain Independent Inventory Control ApplicationInventory Control Application

Separation of Supermarket Domain SpecificsSeparation of Supermarket Domain Specifics Leverage Commonalties for Leverage Commonalties for

Focused, Independent Design/Development Future Products

RelevanceRelevance Domain-and-Organization-Specific Reuse Expand to 24 hour Mom & Pop Stores Expand to Other Retail Markets

E.g., Auto parts, Clothing, Toy, etc.

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Reusability in HTSS DomainReusability in HTSS Domain

Where do Changes for Other Domains Occur?Where do Changes for Other Domains Occur?

Specific Applications for Big Y or Shaw’s or Stop/Shop (S)

Root classes for Items, ItemDB, etc., which are Most General.

Inventory Control/Other Components.

Classes Specific to Grocery Store Domain.

)(G0

)(G1

)(G2

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Inventory ControlOther Components.

Classes Specific to Grocery Store Domain.

)(G0

)(G1

)(G2

Inventory Control Tool for Ordering Items from Suppliers

Cost Accounting Tool for Tracking Net and Gross Profit

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Inventory Control/Other Components.

Classes Specific to Grocery Store Domain.)(G0

)(G1)(G2

Classes forLargeSupermarket

Classes forSpecialtySupermarket

Classes for24 HourConvenience

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Related Classes and HierarchiesRelated Classes and Hierarchies

Class X is Related to Class YClass X is Related to Class Y if they are Related if they are Related and Concept and are and Concept and are Expected to be ReusedExpected to be Reused TogetherTogether in Future Systems in Future Systems

Class X Related to Class Y is Class X Related to Class Y is Subjectively Subjectively AssignedAssigned by Software Engineer (Producer) by Software Engineer (Producer)

When Class X is Related to Class YWhen Class X is Related to Class Y X and All of X’s Descendants are Related to

Y and All of Y’s Ancestors Thus, to Reuse X or X’s Descendants, you

Must Reuse B and All of B’s Ancestors Class X Related to Y if Y at Same or Higher

Level! Related Classes Promote Reuse, Since They are Related Classes Promote Reuse, Since They are

Expected to be Reused TogetherExpected to be Reused Together

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Related Hierarchies/Reusable Related Hierarchies/Reusable ComponentsComponents

Two Sub-Hierarchies are Related if to Reuse One, Two Sub-Hierarchies are Related if to Reuse One, you Must Reuse the Otheryou Must Reuse the Other

Purpose: Purpose: Identify Reusable Dependencies Among Identify Reusable Dependencies Among Related ClassesRelated Classes

Reusable Component: Reusable Component: A Set of Related Classes that A Set of Related Classes that are Expected to be Reused as a Groupare Expected to be Reused as a Group

0G

0G 0G

SS0G

0G

SS0G

SS

A Sub-Hierarchies BA Sub-Hierarchies B

RR

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Related Characterization in Related Characterization in Levels of Components - HTSSLevels of Components - HTSS

Item


)(G0

)(G1 )(G1Environ )(G1RR

DairyItemProduceItem DeliItem SubZero RTemp

Does Does RR from Environ to PerishItem Make Sense? from Environ to PerishItem Make Sense? Should Should RR be from PerishItem to Environ? be from PerishItem to Environ?

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What are Dependencies Among Classes?What are Dependencies Among Classes?

Object Inclusion: Object Inclusion: Class Contains a Instance of Class Contains a Instance of Another ObjectAnother Object

Attribute Definition: Attribute Definition: Class Contains Attribute that Class Contains Attribute that is the Type of Another Objectis the Type of Another Object

Method Invocation: Method Invocation: Class Invokes a Method Class Invokes a Method Defined on Another ObjectDefined on Another Object

GoalsGoals Classify and Understand Dependencies Assess “Good” vs. “Bad” Dependencies Change “Bad” to “Good” by

Changing Class from S to G or G to S Moving Code and/or Method Calls Splitting a Class into Two Classes Merging Two Classes

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Reusing Sub-Hierarchies in Reusing Sub-Hierarchies in Different Components - HTSSDifferent Components - HTSS

Will be reused with Componentsfor another domain,e.g., Toy Store

Will be reused with Componentsfor different Super-market Companies

Item

...DairyItemProduceItem DeliItem


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Transitivity in Inheritance and Transitivity in Inheritance and Related RelationshipsRelated Relationships

Base CaseBase Case: Related Characterization is : Related Characterization is TransitiveTransitive, , but not but not CommutativeCommutative

AA BB CCR R

Case 1Case 1: A is : A is notnot related to X related to X Dependencies from A to X Dependencies from A to X are are notnot Desirable Desirable

Recall: We Reuse X and AllRecall: We Reuse X and All of Its Ancestors, But Not of Its Ancestors, But Not B’s Ancestors to Reuse AB’s Ancestors to Reuse A

AA

BB

CC

XX

R

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Transitivity in Inheritance and Transitivity in Inheritance and Related RelationshipsRelated Relationships

BB

AA

CC

XX

R

Case 2Case 2: X is Related to A : X is Related to A Dependencies from X to Dependencies from X to Both A and B are Both A and B are DesirableDesirable

When Reuse X, Since X When Reuse X, Since X Related to B, we Reuse B and Related to B, we Reuse B and All of Its Ancestors (A)All of Its Ancestors (A)

Thus, Dependencies Between Thus, Dependencies Between X and A are Okay!X and A are Okay!

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Evaluative Metrics and MethodologyEvaluative Metrics and MethodologyObjective Measures of DependenciesObjective Measures of Dependencies

Object-Oriented Design: Object-Oriented Design: Collection of General and Specific Classes, with Related Characterizations

Recall Dependencies Among ClassesRecall Dependencies Among Classes Object Inclusion: Another Instance within Class Attribute Defn.: Attribute Type of Class Method Invocation: Defined on Another Class

Quantify Dependencies for ReuseQuantify Dependencies for Reuse Good: Promotes Reuse - Leave Alone Bad: Hinders Reuse - Try to Change Okay: No Impact on Reuse

GoalsGoals Classify and Understand Dependencies Measure Reuse Potential

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Dependencies Among Related ClassesDependencies Among Related Classes

Remember, G/S are Subjectively Assigned by Remember, G/S are Subjectively Assigned by Software DesignerSoftware Designer

The Two G classes are Related The Two G classes are Related Related Classes are Intended to be Reused Related Classes are Intended to be Reused

TogetherTogetherGood (1)

G

S

G

SOkay (5)

Okay (7)

Bad (3)

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Sample Dependencies in HTSSSample Dependencies in HTSS

InvCont

DeliIC

Item

DeliItem

Good (1)

Okay (5)

Okay (7)

Bad (3)

InvCont and Item are Related InvCont and Item are Related ClassesClasses

InvCont to Item Dependencies InvCont to Item Dependencies are Good: Reused Togetherare Good: Reused Together

Dependency from InvCont to Dependency from InvCont to DeliItem is ProblemDeliItem is Problem Don’t Want to Reuse

InvCont with DeliItem ManagerGUI with InvCont

Includes Useless DeliItem Dependencies from DeliIC to Dependencies from DeliIC to

Item and/or DeliItemItem and/or DeliItem Don’t Impact Reuse Can Reuse Item and

DeliItem w/o DeliIC

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Dependencies Among Non-Related Dependencies Among Non-Related ClassesClasses

Remember, G/S are Subjectively Assigned by Remember, G/S are Subjectively Assigned by Software DesignerSoftware Designer

The Two G Classes are Not RelatedThe Two G Classes are Not Related Non-Related Classes are Non-Related Classes are NOT NOT Intended to be Intended to be

Reused TogetherReused Together

Okay (6)

Okay (8)

G

S

G

S

Bad (2)

Bad (4)

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Sample Dependencies in HTSSSample Dependencies in HTSS

InvCont

DeliIC

Person

Shopper

Bad(2)

Okay (6)

Okay (8)

Bad (4)

InvCont and Person are Classes InvCont and Person are Classes that are Not Relatedthat are Not Related

InvCont to Person or Shopper InvCont to Person or Shopper Dependencies are BadDependencies are Bad Don’t Want to Reuse

Person/Shopper with InvCont

Must Reuse - Problem! Dependencies from DeliIC to Dependencies from DeliIC to

Person and/or ShopperPerson and/or Shopper Don’t Impact Reuse Can Reuse Person and

Shopper w/o DeliIC However, Poor Design if

DeliIC Needs Person or Shopper!

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Summarizing Couplings ofSummarizing Couplings ofRelated ClassesRelated Classes

Type 1: Good for ReuseType 1: Good for Reuse Two General Classes are Reused Together

Type 3: Bad for ReuseType 3: Bad for Reuse General to Specific To Reuse, Specific Must be Included Added Functionality with No Purpose Change to Type 1 or 5/7

Types 5/7: Okay for ReuseTypes 5/7: Okay for Reuse No Impact Specific Classes Not Reused in New

Application May Improve Reuse if Changed to Type 1

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Summarizing Couplings ofSummarizing Couplings ofNon-Related ClassesNon-Related Classes

Type 2: Bad for Reuse - Two General Classes Type 2: Bad for Reuse - Two General Classes Not Expected to be Reused Together since Not

Related Change to Type 6/8

Type 4: Bad for ReuseType 4: Bad for Reuse General to Specific To Reuse, Specific Must be Included Added Functionality with No Purpose Change to Type 6/8

Types 6/8: Okay for ReuseTypes 6/8: Okay for Reuse No Impact Specific Classes Not Reused in New

Application

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Sample Actions to Improve ReusabilitySample Actions to Improve Reusability

Coupling Among Related Among Unrelated

G G Type (1)Good for Reuse

Type (2)Bad for ReuseMove Src./Dst. to Specific

G S Type (3)Bad for ReuseMove Dst. to General

Type (4)Bad for ReuseMove Src. To Specific

S G Type (5)Can Improve if MoveSrc. to General

Type (6)No Impact on Reuse

S S Type (7) - Can Improveif Move Src./Dst. to Gen.

Type (8)No Impact on Reuse

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Reuse GuidelinesReuse Guidelines

Methodological Basis for Increasing ReuseMethodological Basis for Increasing Reuse Designer Supplies General/Specific/Related for

the Classes/Hierarchies in Application Reuse Analysis Tool Calculates Couplings and

Identifies Types of Reuse (Good, Bad, Okay) Ideal Result: Maximize Reuse via CouplingsIdeal Result: Maximize Reuse via Couplings

Type 1: G to G for Related Classes Type 8: S to S for Non-Related Classes

Extended Guidelines: Menu of ChoicesExtended Guidelines: Menu of Choices Different Ways to Move Couplings Considers Impact of Movement on Design

Goal: Iterative Improvement in ReusabilityGoal: Iterative Improvement in Reusability

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Core Guidelines to Move Couplings to Core Guidelines to Move Couplings to Increase Reuse PotentialIncrease Reuse Potential

G

S

G

S

Type 2

Type 8

G

S

G

S

Type 4

Type 8

G

S

G

S

Type 5

Type 1 G

S

G

SType 7

Type 1

Type 1G

S

G

S

Type 3

G

S

G

SType 7

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Extended Guidelines for Extended Guidelines for Improving ReusabilityImproving Reusability

Core Guidelines Emphasize Local BehaviorCore Guidelines Emphasize Local Behavior To Remove “Bad” or Improve “Okay” Coupling, To Remove “Bad” or Improve “Okay” Coupling,

Move Cause of the Coupling (e.g., Method Call)Move Cause of the Coupling (e.g., Method Call) Moving a General Method to Specific Class Moving a Specific Method to General Class

Moving Method Up/Down a Hierarchy, Which Moving Method Up/Down a Hierarchy, Which Alters the Coupling, Alters the Coupling, Can Impact ElsewhereCan Impact Elsewhere

Expand the Analyses to Other Couplings of the Expand the Analyses to Other Couplings of the Source and Destination of the Bad Coupling Source and Destination of the Bad Coupling Couplings to Source when Moving Down Couplings to Destination when Moving Up

Extended Guidelines: Menu of ChoicesExtended Guidelines: Menu of Choices

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Extended Guidelines to Improve ReuseExtended Guidelines to Improve ReuseIdentifying the ProblemIdentifying the Problem

S

G

S m()

G G

Type 7

G

S

G

S

Type 3

Type 7

Recall

G

S

G

S

m()G Type 3

Suppose

What has Occurred?

REUSE--49

Extended Guidelines to Improve ReuseExtended Guidelines to Improve ReuseIdentifying the ProblemIdentifying the Problem

S

G

S m()

G G

Type 5

Suppose

What has Occurred?

G

S

G

S

m()G

Type 1

G

S

G

S

Type 5

Type 1

Recall

REUSE--50

Extended Guidelines for Extended Guidelines for Type 3Type 3 Couplings Couplings

Move Coupling Dst. to General ClassMove Coupling Dst. to General Classor Change Dst. To a General Classor Change Dst. To a General Class Type 3 to Type 1 May Introduce Couplings from G

Dst. to Specific Classes Move Coupling Src. to Specific ClassMove Coupling Src. to Specific Class

or Change Src. To a Specific Classor Change Src. To a Specific Class Type 3 to Type 7 May Introduce Couplings from

General Classes to Specific Src. Change to Non-Related/Follow Change to Non-Related/Follow Type 4Type 4 Detailed Evaluation of ImplementationDetailed Evaluation of Implementation Key ConcernsKey Concerns

Local Changes with Global Impact “Wrong” Choice Degrades Reuse

G

S

G

S

Type 3

Among Related

REUSE--51

Removing Removing Type 3Type 3 Couplings in HTSS Couplings in HTSSWhich Changes Make Sense?Which Changes Make Sense?

InvCont

DeliIC

Item

DeliItem

Type 3

Change InvCont to S or DeliItem to GChange InvCont to S or DeliItem to G Neither Makes Sense Against Design Intent!

Move Coupling Dst. to General ClassMove Coupling Dst. to General Class Find Problem Method Call,

Attribute Access, Object Inclusion Move from DeliItem and Item Type 3 to Type 1

Move Coupling Src. to Specific ClassMove Coupling Src. to Specific Class Find Problem Method Call,

Attribute Access, Object Inclusion Move from InvCont and DeliIC Type 3 to Type 7

Detailed Evaluation of ImplementationDetailed Evaluation of Implementation Note: Maintain Application SemanticsNote: Maintain Application Semantics

Type 1

Type 7

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Move Coupling Src. to Specific ClassMove Coupling Src. to Specific Classor Change Src. To a Specific Classor Change Src. To a Specific Class Type 2 to Type 6 May Introduce Couplings from

General Classes to Specific Src. Move Src. and Dst. to Specific ClassesMove Src. and Dst. to Specific Classes

Type 2 to Type 8 May Introduce Couplings from G

Src. to Specific Dst. Move Coupling Dst. to Specific ClassMove Coupling Dst. to Specific Class

or Change Dst. To a Specific Classor Change Dst. To a Specific Class Follow Type 4 Guidelines

Change to Related/Change to Related/Type 1Type 1/Design /Design Impact Must be Evaluated!Impact Must be Evaluated!

Detailed Evaluation of ImplementationDetailed Evaluation of Implementation

G

S

G

S

Type 2

Non-Related

REUSE--53


Move Coupling Dst. to General ClassMove Coupling Dst. to General Classor Change Dst. To a General Classor Change Dst. To a General Class Type 4 to Type 2 - No Help

Move Coupling Src. to Specific ClassMove Coupling Src. to Specific Classor Change Src. To a Specific Classor Change Src. To a Specific Class Type 4 to Type 8 May Introduce Couplings from

General Classes to Specific Src. Change to Related/Follow Change to Related/Follow Type 3Type 3 Detailed Evaluation of ImplementationDetailed Evaluation of Implementation

G

S

G

S

Type 4

Non-Related

REUSE--54

Summary on Extended GuidelinesSummary on Extended Guidelines

Total Alternatives for Removing “Bad” Couplings:Total Alternatives for Removing “Bad” Couplings: Type 2, 3, 4: Seven Possibilities Each: 21 Total Type 5, 7: 3 Total

Changing from G to S or Movement of Coupling Changing from G to S or Movement of Coupling Potential to Impact: Potential to Impact: Couplings to Source Couplings from Destination

Result: Movement May Result: Movement May DecreaseDecrease Reuse Potential! Reuse Potential! Two-Fold Solution:Two-Fold Solution:

Design Support for OO Reuse Metrics and Evaluation within UML, Design Patterns, etc.

Analytical Tool for Evaluating Reuse Potential of C++, Ada95, or Java Applications/Libraries

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Utilizing Reuse MethodologyUtilizing Reuse MethodologyEvaluate Evolving Design/ImplementationEvaluate Evolving Design/Implementation Constructing New ApplicationsConstructing New Applications

Software Design Proceeds in Stages Today’s Norm: Incremental Development and

Rapid Prototyping General/Specific Classes/Related ComponentsGeneral/Specific Classes/Related Components

Assigned Initially as Classes are Generated Refined Throughout Increments/Versions G to S, S to G, etc. Related Components as Design Begins to

Mature with Additional Details Use Methodology to Find/Correct “Problems”

Video Rental System Test-Bed Video Rental System Test-Bed

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Utilizing Reuse MethodologyUtilizing Reuse Methodology Investigate Reusability of Legacy Code Investigate Reusability of Legacy Code

Reusability of Legacy CodeReusability of Legacy Code Examine Legacy Code in Detail Talk/Contact Domain Experts with Corporate

Knowledge of Code General/Specific Classes/Related ComponentsGeneral/Specific Classes/Related Components

Take “Educated Guess” for G/S Classes and Related Components

Run DRE and Find/Correct Problems Re-evaluate Legacy Code with Different

“Educated Guesses” Compare/Contrast Results to Identify the “Best”

way to Characterize Classes/Components FinancialFrame as a Test-BedFinancialFrame as a Test-Bed

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The Video Rental System (VRS)The Video Rental System (VRS)

VRS is for On-Line (Browser) Rental TapesVRS is for On-Line (Browser) Rental Tapes Maintains Customer and Video Databases Tracks Borrowing/Returning of Tapes Logs Rented Tapes CGI, C++, Netscape/Explorer From Video Rental to Auto Parts Undergraduate Project: Spring 1997 - VRS-1 Repeated as Grad Project: Fall 1998 - VRS-2

Goals:Goals: Demonstrate General/Specific/Related Ideas Incorporate/Reuse Design in Future System Study Effectiveness Approach in Identifying

and Removing Non-Reusable Dependencies

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General and Specific Classes in VRS-1General and Specific Classes in VRS-1

VideoStoreInterface (S)

StoreInterface (G)

VideoCustomer (S)

Customer (G)

VideoCustomerInterface (S)

CustomerInterface (G)

VideoTape (S)

Item (G)

VideoTapeDB (S)

ItemDB (G)

RentedTapeDB (S)RentedTape (S)

CustomerDB (G)

HistoryList (G)

Transaction (G)

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DRE and VRS-1DRE and VRS-1Tracking Incremental VersionsTracking Incremental Versions

Type Metr I II III IV V VI VII

Good CC1 8 54 79 109 166 167 193

Bad CC2 0 0 0 0 0 0 0

Bad CC3 6 0 0 0 4 4 0

Bad CC4 0 0 1 1 0 0 0

Impr CC5 0 19 28 39 94 92 75

Impr CC6 0 6 6 18 28 30 25

Okay CC7 0 0 0 0 0 5 0

Okay CC8 0 0 11 11 21 22 26

LOC 410 1386 2088 2695 3784 3824 3867

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Final General/Specific Classes in VRS-2Final General/Specific Classes in VRS-2and Some Related Characterizationsand Some Related Characterizations

VideoStoreInterface (S)

StoreInterface (G)

Customer (G)

CustomerInterface (G)

Video (S)

Item (G)

VideoItemList (S)

ItemList (G) ReportGenerator (S)

Transaction (G)

VideoTransaction (S)

CustomerList (G)

VideoCustList (S)

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DRE and VRS-2DRE and VRS-2Tracking Incremental VersionsTracking Incremental Versions

Type Metr I II III IV

Good CC1 17 28 26 26

Bad CC2 0 0 0 0

Bad CC3 0 0 1 0

Bad CC4 0 0 0 0

Impr CC5 0 0 2 2

Impr CC6 0 0 3 4

Okay CC7 0 4 3 3

Okay CC8 0 0 0 0

G/SLOCCls.

175/1

325/1

307/6

307/6

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One Type 3 Coupling: G to S DependencyOne Type 3 Coupling: G to S Dependency

Transaction (G)

write_to_checkoutfile()write_to_checkoutfile()


Customer (G)

take_item( )

...tr->calculate_currentdate()tr->calculate_duedate()tr->write_to_historyfile()tr->write_to_checkoutfile()...

calculate_currentdate()calculate_duedate()write_to_historyfile()

• What is the Problem?What is the Problem?• How is it Resolved?How is it Resolved?

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Resolving Type 3 G to S DependencyResolving Type 3 G to S Dependency

Customer (G)

take_item( )

Transaction (G)

write_to_checkoutfile()write_to_checkoutfile()


calculate_currentdate()calculate_duedate()write_to_historyfile()

...tr->calculate_currentdate()tr->calculate_duedate()tr->write_to_historyfile()take_item_specific()...

take_item_specific()take_item_specific()

VideoCustomer(S)

((VideoTransaction *) tr) -> write_to_checkoutfile()

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Design Reusability Evaluation (DRE) Design Reusability Evaluation (DRE) ToolTool

What is DRE?What is DRE? Java-Based Tool for Analyzing Reusability Takes C++, Ada95, and Java Code as Input Works with General/Specific/Related as

Subjectively Defined by Software Designer Analyzes Couplings to Identify, for Each Type

(1 to 8), the Number of Couplings Allows Designer to Investigate Cause of and

Correct “Bad” or Improve “Okay” Couplings DRE can be Utilized in Different WaysDRE can be Utilized in Different Ways

Evaluate Evolving Design/Implementation Investigate the Reusability of Legacy Code

Examples of Video Rental System/FinancialFrameExamples of Video Rental System/FinancialFrame

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DRE ProcessDRE Process

DRE Process: User RoleDRE Process: User Role Step 1: User Selects

DRE Mode Currently Available

in Java and C++ Mode

Ada95 Version May Exist

Step 2: User Selects Directory of Code

DRE Process: Tool RoleDRE Process: Tool Role Step 3: Tool Parses

through Source Code in Selected Directory

Step 4: Tool Returns Class Names and Class Pairs to User Interface

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DRE Process: User RoleDRE Process: User Role Step 5: User Selects

General Classes

Step 6: User Selects Related Classes

7: User Requests Calculation of Coupling Counts

DRE Process: Tool RoleDRE Process: Tool Role Step 8: Tool Makes

Calculation Based on User’s Input

Step 9: Tool Returns Coupling Counts to User Can Present

Calculations Only Can Present

Calculations, Possible Errors, Improvement Ideas

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DRE Process: User RoleDRE Process: User Role Step 10: User May Select Simulation of

Changes

DRE Process: Tool RoleDRE Process: Tool Role Step 11: Tool Outlines Possible Improvements

DRE Process: User RoleDRE Process: User Role Step 12: User Chooses Improvements

DRE Process: Tool RoleDRE Process: Tool Role Step 13: Tool Recalculates Coupling Values

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Prototyping Progress in DRE and TCC Prototyping Progress in DRE and TCC (SD & JE)(SD & JE)

Summary of Prototyping MilestonesSummary of Prototyping Milestones Results and Status of CSE367 ProjectResults and Status of CSE367 Project

Work by H. Lin on DRE Work by X. Wang on TCC

DRE StatusDRE Status GUI Finalized Simulator Completed Parser Integrated Help Subsystem Completed

Togethersoft Control Center Status Togethersoft Control Center Status Developed Extensive Set of Plug-ins UML Design Level Reusability Definition

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Main Application Window Main Application Window

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Main Window – Setting GeneralityMain Window – Setting Generality

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Main Window – Setting RelationsMain Window – Setting Relations

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Main Window – Choosing Simulation Main Window – Choosing Simulation OptionsOptions

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Help SubsystemHelp Subsystem

HTML-based Documents Describe Tool & TheoryHTML-based Documents Describe Tool & Theory

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Reuse in Togethersoft Control CenterReuse in Togethersoft Control Center

Integrates Visual Modeling via IDEIntegrates Visual Modeling via IDE Implements UML/Supports Java and C++ Source Code Editing Model/Code Synchronization Open API and Plugin Support (Written in Java)

Single Integrated Design/Development Single Integrated Design/Development Environment with Reusability AssessmentEnvironment with Reusability Assessment

Leverage TCC to Support Reusability at Design Leverage TCC to Support Reusability at Design LevelLevel Incorporate G/S and Related at UML Level Users can Execute Plug Ins for Each Actual Properties for UML Classes Modified

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Reusability in Together CCReusability in Together CC

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ConclusionsConclusions

Comprehensive Reusability Model and EvaluationComprehensive Reusability Model and Evaluation General/Specific/Related Characterizations Capture/Analyze Reusability of OO Software Achieve Highest Gain Through Early

Identification and Reusability Evaluations! Methodology and Empirical VerificationMethodology and Empirical Verification

Guidelines to Encourage Reuse Applicable to Reuse of Designs and Code DRE Tool for C++, Ada95, Java Strong Demonstration of

Domain-and-Organization-Specific Reuse

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Reusable Component Framework(Demurjian) Reusable Component Framework(Demurjian) Status and ObjectivesStatus and Objectives

Work Currently Funded by Electric Boat, Inc. (T. Rando, Work Currently Funded by Electric Boat, Inc. (T. Rando, T. Daggett, and M. Price) and Jointly Conducted with T. Daggett, and M. Price) and Jointly Conducted with USNA (Dr. D. Needham)USNA (Dr. D. Needham)

Planned Research Over Next 12 Months Planned Research Over Next 12 Months Complete Prototypes (DRE /TCC) Genetic Algorithm for Refactoring/Assessment Formal Reuse Model XML/Reuse

Research - Through 2004Research - Through 2004 Focus on Comprehensive Reuse Framework Guided Reusability Assessment/GA Analysis Component Repository with Search Capabilities Leverage Domain/Organization Specificity UML, XML, and Java Components

See:See: http://www.engr.uconn.edu/~steve/DRE/dre.html

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The FinancialFrame ApplicationThe FinancialFrame Application

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A Commercial C++ Framework Containing 441 A Commercial C++ Framework Containing 441 Classes, Proprietary of FinancialCompClasses, Proprietary of FinancialComp

Designed for Reuse in Various Financial Apps.Designed for Reuse in Various Financial Apps. Provides Basic Functionalities of Financial SystemProvides Basic Functionalities of Financial System FinancialFrame’s Challenge - Manage ChangesFinancialFrame’s Challenge - Manage Changes

Framework Constantly Evolving New Functions and Modify Existing Functions

Conceptual Relevance:Conceptual Relevance: Provide Realistic Context for Our Approach Domain-and-Organization-Specific Reuse

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Our Purpose: Work with Existing CodeOur Purpose: Work with Existing Code Establish General and Specific Classes Characterize Related Components Evaluate the Goodness of G/S Characterization

and Identify Potential Problem Areas General Components that are Specific Specific Components that are General

Problematic Relevance:Problematic Relevance: Demonstrate Ability of Approach to Localize

Effect of Changes Describe Ways to Increase FinancialFrame’s

Reuse Potential

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General and Specific Classes in General and Specific Classes in FinancialFrameFinancialFrame

FinancialCompTrader )(G2

FinancialCompAccount )(G2

FinancialCompDesk )(G2

)(G0Main

FinancialCompMain OtherMain

SpecificFCMain (S) SpecificOtherMain (S)

)(G2 )(G2 ...

)(G0YieldModel

DiscountIndexBond )(G1 )(G1 Bill )(G1

)(G0CashFlowAnalyzer

...

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Related Characterizations in Related Characterizations in Levels of Components - FinancialFrameLevels of Components - FinancialFrame

Classes/Sub-Hierarchies can be Related if and only Classes/Sub-Hierarchies can be Related if and only if Classes (or Sub-Hierarchy Roots) are General if Classes (or Sub-Hierarchy Roots) are General and at the Same or Higher Leveland at the Same or Higher Level

Specific applications at FinancialComp (S)

Root classes of strategies andother most General classes (Main)

Bond or other strategy Components

Classes specific to FinancialComp

)(G0

)(G1

)(G2

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Related Characterization in Related Characterization in Levels of Components - FinancialFrameLevels of Components - FinancialFrame

...

)(G0YieldModel

DiscountIndexBond )(G1 )(G1Bill )(G1

Bond )(G1

R

Bond is Related to IndexBondBond is Related to IndexBond When Bond is Reused, so Must IndexBond and When Bond is Reused, so Must IndexBond and

YieldModel YieldModel Hence, IndexBond and its Ancestor (YieldModel) Hence, IndexBond and its Ancestor (YieldModel)

are Reused!are Reused!

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Reusing Sub-Hierarchies in Reusing Sub-Hierarchies in Different Components - FinancialFrameDifferent Components - FinancialFrame

Dependencies Among General Related ClassesDependencies Among General Related Classes Not a Hindrance to Reuse Represents Valuable Design Knowledge

)(G0Main

FinancialCompMainOtherMain

SpecificFCMain (S)SpecificOtherMain (S)

)(G2)(G2

Will be reused with Componentsutilizing another company’s databases

Will be reused with Componentsutilizing FinancialComp’s database

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An Example of Case 1 in FinancialFrameAn Example of Case 1 in FinancialFrame

FinancialCompMain FinancialCompMain RR FinancialCompTrader FinancialCompTraderThus, Dependencies Between are DesirableThus, Dependencies Between are Desirable

Main is Main is not Rnot R to FinancialCompTrader to FinancialCompTraderThus, Dependencies Between Hinder ReuseThus, Dependencies Between Hinder Reuse

For For “Blue” “Blue” Component, we Don’t Want to Have to Component, we Don’t Want to Have to Reuse FinancialCompTrader with Main!Reuse FinancialCompTrader with Main!

)(G0Main

FinancialCompMainOtherMain )(G2)(G2

FinancialCompTrader )(G2

R

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An Example of Case 2 in FinancialFrameAn Example of Case 2 in FinancialFrame

...

)(G0YieldModel


Bond )(G1

R

Class Bond Class Bond RR to both IndexBond and YieldModel to both IndexBond and YieldModel Thus, Dependencies from Bond to IndexBond and Thus, Dependencies from Bond to IndexBond and

YieldModel are Desirable and Reusable!YieldModel are Desirable and Reusable! When Bond is Reused, So is IndexBond and When Bond is Reused, So is IndexBond and

YieldModel!YieldModel!

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The FinancialFrame ApplicationThe FinancialFrame ApplicationInitial Assumptions on G/S and RelatedInitial Assumptions on G/S and Related

...

)(G0YieldModel


Bond )(G0

FinancialFrame Composed of Multiple Algorithm FinancialFrame Composed of Multiple Algorithm FamilitesFamilites

All Root Classes are G(0) with Subclasses G(1)All Root Classes are G(0) with Subclasses G(1) All Other Classes are G(0)All Other Classes are G(0) Use Actual Couplings in Code to Define Related Use Actual Couplings in Code to Define Related

CharacterizationCharacterization

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Evaluation of FinancialFrameEvaluation of FinancialFramePossible ScenariosPossible Scenarios

Dependencies from to ClassesDependencies from to Classes Occurring from a General Class (Bond) to

Classes Specific to a Component (IndexBond) Such Couplings Require a Specific Class that is

Not Needed to be Reused with the General Root Reported as Undesirable Couplings (Type 3/4)

0G 1G

...

)(G0YieldModel


Bond )(G0

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Revising FinancialFrame ApplicationRevising FinancialFrame Application

...

)(G0YieldModel


Bond )(G1 R

Bond is Changed from to Bond is Changed from to A Component Consisting of Bond, IndexBond, A Component Consisting of Bond, IndexBond,

and YieldModel is Definedand YieldModel is Defined When Bond Reused, So Must IndexBond and When Bond Reused, So Must IndexBond and

YieldModel - Other Classes Not NeededYieldModel - Other Classes Not Needed However, YieldModel can Be Reused in IsolationHowever, YieldModel can Be Reused in Isolation Thus, Modifications to Component Only Affect Thus, Modifications to Component Only Affect

Reusers of ComponentReusers of Component

0G 1G

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Evaluation of FinancialFrameEvaluation of FinancialFramePossible ScenariosPossible Scenarios

Dependencies from to Classes Dependencies from to Classes Occurring from a Specific Class to Other

Classes Specific & Unrelated to a Component Bond Related to Class Outside Component Such Couplings Require a Specific Class in

One Component to be Reused in Another Component, Where it is Not Needed

Reported as Undesirable Couplings (Type 2)

1G 1G

...

)(G0YieldModel


Bond )(G1 R

1G

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Reusability of FinancialFrame Reusability of FinancialFrame ComponentsComponents

Undesirable Couplings Identified via Either Undesirable Couplings Identified via Either Scenario can be Removed to Increase ReuseScenario can be Removed to Increase Reuse

Results of Such Actions w.r.t. FinancialFrameResults of Such Actions w.r.t. FinancialFrame Classes can be Reused with Classes When a Class is Modified, Only Users of

Particular Component(s) are NotifiedBad Coupling No Longer Present!Bad Coupling No Longer Present!

Each Component Can be Reused “As is” Classes Outside of Component No Longer

Needed Cannot Illustrate Due to Proprietary SoftwareCannot Illustrate Due to Proprietary Software Similar Changes to VRS-2 OccurSimilar Changes to VRS-2 Occur

1G1G

0G

A Framework, Methodology and Tool for Reusable Software Components

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