The Re-engineering and
Reuse of Software
Patrick A.V. Hall and Lingzi Jin
Vol 1, p.335-351
Presented by: Andrew Wheeler
Overview
Definitions
 Introduction
 Historical Background
 Implementations
 Challenges
 Conclusions

Definitions

Re-engineering
– The combination of reverse engineering and forward
engineering
– The concept of “redoing” a software system

Reuse
– Using a given piece of software to solve more than
one problem

Reverse engineering
– The tools and methods used to understand software
– Figuring out a software system for potential
redeployment
Introduction

Software re-engineering and reuse are
concerned with maximizing software
usage for any given development effort
– Both are used to maximize profit and
minimize turnaround time

Software re-engineering and reuse also
help minimize staff
– The more code you can reuse the less code
you have to write and rewrite
Introduction (cont)

Reuse not only applies to using a piece of
software:
– Reuse designs and ideas thrown out during
design phase
– May have use in other applications

Reverse engineering and reuse can help
recover lost investment
– Time has already been placed into designing
it the first time around.
Historical Background - Reuse

Reuse dates back to sharing of algorithms
through publications
– Reuse of high level language and packages
– Textbook publications

Use of macros and similar assembly
instructions
– Subroutine entry and exit
– For loops, if blocks, arithmetic
Historical Background
– Reuse (cont)

Reuse associated with flexibility
– Parameterization
– Build scripts
Historical Background
- Re-engineering

Flow-charting tools have been around for
awhile
– Now evolved into UML and sequence
diagrams

Cross reference listings of variables
– Helps understand large pieces of software

Originally designed to help maintain
COBOL legacy systems around 1980s
Implementations – Reuse

Integration into lifecycle
– Building phase to construct the reusable
components into a library
– Incorporating those reusable components into
the building of a software system
 Time required to account for integration issues
Implementations – Reuse
Component based
Central to reuse
 Design for “plug and play”
 Which components comes from domain
analysis

– File Input/Output component not needed for a
system that won’t write to disk
Implementations – Reuse
Component based
Give clear descriptions and classifications
 Avoid over generalization

– Map instead of tree

Object oriented programming lends itself
to reuse
– Objects are often in reusable component form
– Inheritance provides contexts for reuse
 Sorted Map inherits from Map

Size or granularity
Implementations – Reuse

Reuse in design
– Component or components could fulfill a requirement
based on specifications
– If multiple components are used then requirements
must be broken down further
 Logging utility = Time utility + Format utility + File utility +
Process input utility
– Identification, evaluation, modification, and
integration

White-box reuse
– Reuse with simple modifications of code

Frameworks
Implementations – Reuse

MIL – Module Interconnection Languages
– Prieto-Diaz, et. al (1986)
– Going beyond procedure calls in code
– Helps in system building another higher
language

Design with reuse involves transforming
the outputs of one components to the
inputs of another
Implementations – Re-engineering

Reverse engineering involves abstracting
the current system and revealing the
nature of the system
– Describe the system to a non technical person

Documentation of class methods and
members could be used during the
process
– Outlining tools and sequence diagrams have
been in use for many decades
Implementations – Re-engineering

Use of formal transformations
– Gather details about an efficient algorithm
that may be difficult to understand

Use of wide spectrum language - Ward
– An interactive system to abstract details of
implementation into Z language and
implement Z language in code language of
choice
Implementations – Re-engineering

Use of reverse engineering back to specifications
– Lano, et. al
– Used to reverse engineer COBOL applications

Using good coding practices helps the reengineering process
– Self documenting code

Knowledge of higher level domain concepts
helps re-engineering
– Knowing for what purpose the software system was
used
Implementations – Re-engineering

Using design patterns in code
– Helps to know the purpose for a software
system and helps the forward process by
knowing how to build the system

Object-oriented programming facilitates
the reverse-engineering process
– Components of the high level systems share
the names of the objects
Implementations – Domain Analysis
Identify the major concepts and the
relationships between the concepts
 Usage of components is determined by the
domain in which they will be used
 Determine if components needed have already
been built
 Helps guide the production of components for
better reuse

– Adequate domain models help scope the components
and their usage
Challenges of Re-engineering and
Reuse

Personnel issues
– “Why buy when you can build?”
 Reuse doesn’t always mean buying
– Contrast to electronic engineering
 Build your own microprocessor?

Payoff issues
– Rewarding someone for building a reusable
component by royalties?
Challenges of Re-engineering and
Reuse

Economical issues
– Payoff occurs after component production
– Most companies are geared towards
producing a system
 Gain another contract and reduce turnaround time
from reuse
– Accounting treats software as consumable
and not capital
 Concept of making software reusable capital like a
desk
Challenges of Re-engineering and
Reuse

Legal issues
– Protection against physical piracy and
intellectual piracy
– Use of proprietary software remedies certain
issues
Conclusions

Software reuse, re-engineering, and reverse
engineering are cutting-edge methodologies
– Product Line and Battle Command Product Line

Technology has caught up to these practices
– UML

There is a future in adding reuse to the software
lifecycle
– Economic gains must be established