Paper Reviewon

Towards a Better Understanding of Software Evolution:

An Empirical Study on Open Source Software

Presented ByMd. Shafiuzzaman

MSSE 0310

Introduction of the Paper

• Authors: Guowu Xie, Jianbo Chen, Iulian Neamtiu, Department of Computer Science and Engineering, University of California, USA

• Published in: IEEE International Conference on Software Maintenance

• Publication Year: 2009

Area of Inquiry

Software Evolution Process

Verify existing laws of software evolution

Analyse evolution patterns

Research Questions

• Verify whether existing software evolution models are sufficient enough to characterize the software evolution process

Lehman’s Eight Laws (1970)i. Continuing Change ii. Increasing Complexityiii. Self Regulationiv. Conservation of Organizational Stabilityv. Conservation of Familiarityvi. Continuing Growthvii.Declining Qualityviii.Feedback System

Applications

• 7 open source project and 653 official releases

I - Continuing Change

• A program must continually adapt to its environment, otherwise it becomes progressively less useful

II - Increasing Complexity

• A program evolves, its complexity increases

III - Self Regulation

• Evolution of large software systems is a self-regulating processSelf Regulation: The system adjusts its size throughout its lifetime

IV - Conservation of Organizational Stability

• Productive output tends to stay constant throughout a program’s life time

V - Conservation of Familiarity

• Incremental system growth tends to decline source code familiarity

VI - Continuing Growth

• Programs usually grow over time to accommodate pressure for change and satisfy increasing set of requirements

• LOC• Number of modules• Number of definitions (types, global variables, and functions)

VII - Declining Quality

• Software quality appears to be declining over time• Quality metric: defect density (defect/LOC)

VIII - Feedback System

• System growth slows down over time

Observations

• Laws I, II, III, and VI are confirmed• Continuing Change • Increasing Complexity• Self Regulation• Continuing Growth

• ‘Conservation of Organizational Stability, Conservation of Familiarity, Declining Quality, Feedback System’ can’t be validated

Research Weaknesses and Limitations

• Lack of process data for the open source projects• Limited to evolution aspects of Lehman’s laws