Planning the Reengineering of Legacy Systems, by Harry M' Sneed

1
Planning the Reengineering of Legacy Systems, by
Harry M. Sneed

• Reviewed by Odd Petter N. Slyngstad for DT8100,
  27/1/2005

2
Overview

• Looks at the following aspects of re-engineering
• Cost-effectiveness
• Preferability
• Provides a method to quantify costs prove
  benefits of reengineering as a method to
  improve existing software prods and procs

3
Planning overview

• 5-step procedure
• Project justification (increased quality,
  efficiency etc)
• Portfolio analysis (prioritize candidate apps)
• Cost estimation (include all sw components)
• Cost-Benefit analysis (reengineering
  maintenance cost value increase)
• Contracting (max level of distribution, avoid
  bottlenecks)
• (total planning estimated at 6 months)

4
Project justification

• Prove that it will reduce maintenance cost,
  improve quality by
• Introducing a measurement program
• Analyzing software quality
• Analyzing maintenance costs
• Assessing the softwares business value

5
Portfolio Analysis

• Plots applications in terms of business value and
  technical quality (ex iso9126)
• Use chi-square chart (see article)

6
Cost Estimation

• Cost of the actual reengineering must be lower
  than the benefits for specific projects...

7
Reengineering definitions and objectives

• Business-process reengineering
• Business process administration, supported by
  computer processes
• Data reengineering
• Restructuring existing databases
• Software reengineering
• Renovation of applications and software artifacts
  (map descriptions, job-control procedures, data
  structure views etc.)
• Recycling
• Differs from reengineering in the sense that the
  result is a collection of reusable components,
  not a fully working system...

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Cost-Benefit analysis

• Not just benefits of reengineering, also compare
  with benefits of redevelopment and....the
  benefits of doing nothing...
• And other factors such as unavailability, system
  lifetime, user satisfaction (the list goes on)...
• Example A number of factors selected by UBS
  (annual maintenance, annual operations etc. etc.
  etc. see article for full list)

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Contracting

• By time/material or by result (turnkey)
• Task definition
• Derived from the list of objects needing
  reengineering (restructuring, conversion,
  testing, postdocumentation, system testing,
  configuration mgmt, system documentation etc.)
• Effort distribution
• Recommendations on how and where to carry out the
  actual work (testing effort, component
  reengineering etc.)

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Summary

• Reengineering is NOT easy to sell
• Must be justified not only with technical
  concerns, but also with business issues.
• Questions, comments ??