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Reengineering a Low-Quality High-Value Subsystem with Minimal Disruption

publish date: 2026/06/24 21:32:31.667483 UTC

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A subsystem has been classified as 'low quality, high business value' - it is critical to daily operations but is expensive and risky to change. Which of the following approaches would help reengineer such a subsystem while minimizing impact on ongoing operations? Select all that apply.

Reengineer incrementally, validating each change against the running system before proceeding to the next

Delete all historical data immediately to simplify the reengineering effort

Wrap the subsystem with adaptor services that expose better-structured interfaces without changing its internals immediately

Shut down the subsystem entirely for several months with no replacement while reengineering is completed

Maintain parallel operation of the old and new components during a transition period to catch discrepancies

Correct Answer

(1) Wrap the subsystem with adaptor services that expose better-structured interfaces without changing its internals immediately

(2) Reengineer incrementally, validating each change against the running system before proceeding to the next

(3) Maintain parallel operation of the old and new components during a transition period to catch discrepancies

Explanation

Minimal-impact reengineering strategies for a high-value, low-quality subsystem include legacy system wrapping (hiding old interfaces behind new adaptor services), incremental reengineering with validation at each step, and parallel running of old and new components to catch discrepancies before fully cutting over. Completely shutting down a high-value system or deleting data would be highly disruptive and risky.

Reference

Software Engineering, Ian Sommerville, 10th edition

Quizzes you can take where this question appears

Software Evolution - Exercises