Mining Logical Clones in Software: Revealing High

Mining Logical Clones in Software: Revealing High-Level Business & Programming Rules Wenyi Qian1, Xin Peng1, Zhenchang Xing2, Stan Jarzabek3, Wenyun Zhao1 1Fudan University, China 2Nanyang Technological University, Singapore 3National University of Singapore, Singapore

Logical Clones

• may not well documented • revealing high-level rules

Logical Clones • Logical clones consisting of: – Similar methods – Similar code fragments – Similar entity classes – Persistent data projects

Logical Clones • Today’s techniques on clone/similarity detection: – Simple clone (text, token, AST…) – Structural clone (simple clone) – Similar design structures (similarity metrics, machine learning)

• They are not enough to detect high-level clones: – lack of high-level information – need of pre-defined templates, such as certain design pattern

Approach Overview output

input

abstraction

Program Model • • • •

Methods & functional clusters Entity classes Code clones Persistent data objects

Program Model • Methods & functional clusters – Semantic clustering

Program Model • Entity classes – Encapsulating information with getter/setter

Program Model • Code clones – Simple clones in different methods

Program Model • Persistent data objects – Data tables in DB or data entries in files

Mining Process

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Mining Process

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Mining Process

Mining Process

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Mining Process

Mining Process

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Mining Process

Tool: MiLico

Case Study • Project: Opentaps 1.4.0 – 14,351 classes & interfaces – 253,743 methods

• 1690 logical clones mined – at least 3 nodes & 2 instances

Case Study

Categories of Logical Clones • Categories of Mined Logical Clones (manual work) – – – –

Programming Convention (37%) Design Structure (24%) Business Task (23%) Business Process (16%)

Categories of Logical Clones • Programming Convention – Similar ways to implement similar functions

Categories of Logical Clones • Design Structure – Similar interaction structures

Categories of Logical Clones • Business Task – Similar ways to implement similar business task

Categories of Logical Clones • Business Process – Similar business process or sub-process

Human Study • 5 senior graduate students, 2 questions: • Helpful for Programming understanding? • Helpful for Reuse/Evolution?

Human Study

Human Study • 5 senior graduate students, 2 questions: • Helpful for Programming understanding? YES • Helpful for Reuse/Evolution? YES

Discussion • Helpful for reuse, without knowledge of code details • Developers with good domain knowledge will use logical clones better • Making MiLiCo integrated with IDEs will make logical clones more useful

Conclusion • • • •

The concept of logical clones The approach for mining logical clones The tool: MiLoCo A case study, showing that logical clones are helpful in software understanding, reuse and maintainance

Thanks for your attention!