David Grizzanti

1
David Grizzanti

• Evaluating Software Reuse Alternatives An
  Industrial Case Study

2
Introduction

• Software reuse results in
• Lower costs
• Shorter delivery time.
• Software reuse factors include the product line
  approach and the involvement of core assets
• Product developers decide whether to acquire
  these core assets or develop their own
  artifacts
• Decisions should be based on collected data from
  past reuse scenarios

3
Reuse Concepts

• Reuse takes place when an existing artifact is
  used in the development of a software product.
• Two types of reuse black-box and white-box.
• Before any reuse can take place, domain analysis
  must be conducted.
• Domain Analysis begins with information gathering
  and results in candidates for reuse.
• Related Work
• Using software reuse alternatives Hewlett-Packard
  (HP) saw a defect reduction of 15 and a 57
  increase in productivity.

4
Reuse Costing Policies

• Cost of reuse software can be divided into 3
  general categories
• Production Construction Asset Acquisition
  Cost Asset Development Cost Product
  Integration, Verification, and Validation Cost
• Core-Asset Construction Asset Acquisition
  Cost Asset Development Cost
• Infrastructure Construction Repository
  Establishment and Maintenance Cost
• Repository Storage and Cataloging Cost Domain
  Analysis (DA) Cost

5
The Model

• Software construction in the underlying model is
  described along three axes
• Development
• Maintenance
• Reuse
• Artifacts have to be stored and cataloged in the
  core-assest repository before being transferred
  between software products.

6
The Model

• Mining - Fetching products and copying them into
  the repository
• Acquisition - Copying artifacts from the
  repository into specific products
• There are two types of Assets
• Repository Assets cataloged in core-asset
  repository
• Private Assets contained within a product and
  are available for mining or acquisition.

7
Elementary Operations

• Transformation Operations
• Adaptation for Reuse (AR)
• New for Reuse (NR)
• White-Box Reuse (WB)
• New Development (ND)
• Transition Operations
• Cataloged Asset Acquisition (CA)
• Black-Box Reuse (BB)
• Mining and Cataloging (MC)
• Copy and Paste (CP)
• eXternal Acquisition (XA)

8
Case Study Example

• Develop two software products
• Both need a queue structure
• One in C, one in Java
• Previous product implemented the same structure,
  except in Ada.
• Reverse-engineer the Ada package to an
  object-oriented class design
• Sequence of operations
• MC? AR ? CA ? WB
• A reuse scenario was employed here
• To determine the best reuse scenario, compare the
  relative cost of alternative scenarios

9
Cost Components

• Operations involve two assets
• Source Asset
• Target Asset
• Cost of Transformation Operations
• CAR (R,R) CNR (R)
• CWB (P,P) CND (P)
• Cost of Transition Operations
• CCA (R,P) CCP (P)
• CMC (P,R) CXA (R)
• CBB (R,P)

10
Applying Cost Policies

• Costing policy table can easily be adapted to
  accommodate other cost directives.
• Empty N/A to operation
• Full Full cost to operation
• Part Partial cost to operation
• Costs usually incurred when activity doesnt
  involve resulting artifact

11
Typical Reuse Scenarios

• Pure Development (PD)
• Target components are developed from scratch
• Opportunistic Reuse (OR)
• Artifacts exist for reuse, but must be searched
  for
• Controlled Reuse (CR)
• Artifacts are cataloged unchanged then modified
  for use
• Systematic Reuse (SR)
• Artifacts are mined, cataloged, and modified for
  future acquisition
• Alternative Systematic Reuse
• Artifacts are created from scratch and then
  cataloged

12
Industrial Experience

• Model was implemented by ISWRIC (Israel SoftWare
  Reuse Industrial Consortium), a joint project of
  seven Israeli companies
• Three are mainly defense contractors
• The other four produce customizable commercial
  products
• Six of the companies defined and evaluated reuse
  scenarios

13
Industrial Experience

• Sytematic Reuse
• Implemented by five companies
• Three implemented systematic reuse of reusable
  assets
• Two implemented systematic reuse on existing
  assets
• Controlled Reuse
• Implemented by one company
• Reusable assets brought to degree where each
  product can use these assets for specific needs
• Use of this model in Industry has demonstrated
  its potential benefits to various reuse scenarios

14
Industrial Experience - TES Case Study

• Tadiran Electronic Systems Ltd., adopted the
  controlled reuse scenario
• Established a reuse repository
• Allocated resources to each team to perform
  Adaptation for Reuse
• Products were identified as candidates for reuse
  through Domain Analysis
• Four of the assets were software modules with
  sophisticated hardware elements
• The other three were generic human-computer
  interface modules

15
TES Case Study Results

• Cost, in person-hours (bold numbers were actually
  measured whereas others were estimated)
• Except for Asset 5, the implemented scenario
  achieved the least cover over all alternatives
• Asset 5, however shows that systematic reuse
  would have faired better

16
Alternative Reuse Savings

• Between Systematic and Controlled Reuse, largest
  saving was 63 (Asset 7), and lowest savings was
  -28 (Asset 5)
• Savings relative to Opportunistic Reuse were
  between 1-65 and in comparison to Pure
  Development, it was between 42-81

17
Conclusions and Further Work

• Results based on estimated data are subject to
  inaccuracies
• If applied consistently, cumulated data can be
  analyzed for better estimates
• Two major contributions
• Cost model provides a practical tool for
  developers to test different scenarios
• Provides a mechanism to analyze and evaluate
  scenarios at an organizational level
• Other features, such as time-to-market and
  product quality also improve with reusing
  software assets
• In the future, working to include models for
  these attributes

18
References

• Tomer, Amir Goldin, Leah Kuflik, Tsvi Kimchi,
  Esther Schach, Stephen R. "Evaluating Software
  Reuse Alternatives A Model and Its Application
  to an Industrial Case Study." IEEE Transactions
  on Software Engineering. Volume 30. Issue 9.
  September 2004. pp601-612
• P. Clements and L.M. Northrop, Software Product
  Lines Practices and Patterns. Addison-Wesley,
  2001.