Reverse engineering is the process of analyzing a system to understand how it works in order to recreate or re-implement the system. It involves determining the system's components, architecture, and algorithms by working backwards from its executable form. Reverse engineering is used to recover lost information, assist with maintenance, migrate systems to new platforms, and facilitate software reuse. It requires discovering the system's abstraction levels and mapping between its problem domain and implementation. Common reverse engineering tasks include program understanding, redocumentation, component identification, and abstraction discovery.

1. Reverse Engineering

2. Contents
• What is Reverse Engineering (RE)?
• Why do we need Reverse Engineering?
• Scope and Tasks of Reverse Engineering
• Different Approaches
• RE tools
• Conclusions

3. What is Reverse Engineering ?
• You have an unexpected case:
– You finished one course project using Java
– Your program runs OK
– But, by accident, you delete the java file
– How to hand in your project?

4. What is Reverse Engineering ?
• You have an unexpected case:
– You finished one course project using Java
– Your program runs OK
– But, by accident, you delete the java file
– How to hand in your project?
• Reverse Engineering

5. What is Reverse Engineering ?
Waterfall Model of software development
Requirement
analysis
design
Implementation
Testing and
Maintenance

6. What is Reverse Engineering ?
Forward Engineering
Requirements
Design
Source Code
Behavior

7. What is Reverse Engineering ?
Forward Engineering Reverse Engineering
Requirements
Design
Source Code
Behavior

8. What is Reverse Engineering ?
Abstraction System
Old system New System
Forward Engineering
Re-Implementation
Reverse Engineering
Abstraction

9. What is Reverse Engineering?
• RE encompasses any activity that is done to
determine how a product works, to learn the
ideas and technology that were used in
developing that product.
• RE can be done at many levels
• RE generally belongs to Software
Maintenance

10. The Early Days of RE
• Law of Software Revolution (Lehman, 1980)
• Fundamental strategies for program
comprehension (Brooks, 1983)
• Taxonomy of Reverse Engineering
(Chikofsky&Cross, 1990)
• WCRE (Working Conference on R.E., 1990)
• IWPC (Int. Workshop on Program
Comprehension)

11. Why do we need RE ?
• Recovery of lost information
– providing proper system documentation
• Assisting with maintenance
– identification of side effects and anomalies
• Migration to another hw/sw platform
• Facilitating software reuse

12. Why do we need RE ?
• Benefits
– maintenance cost savings
– quality improvements
– competitive advantages
– software reuse facilitation

13. Difficulties of Reverse Engineering
• Gap between problem
/solution domain
• Gap between concrete
and abstract
• Gap between coherency/disintegration
• Gap between hierarchical/associational

14. Scope and Task of Reverse Engineering
• program understanding
Problem/Application
domain
Program/Implemen.
domain
Mapping

15. Scope and Task of Reverse Engineering
• Redocumentation and/or document
generation
• Recovery of design approach and design
details at any level of abstraction
• Identifying reusable components and
components that need restructuring
• Recovering business rules
• Understanding high-level system description.

16. Discovery of Abstraction
• Discovery of abstraction in large system
– maintenance purpose
– evolution purpose
– reengineering purpose

17. Levels of abstractions
• Application
– Application concepts, business rule, policies
• Function
– Logical and functional specification, non-functional requirement
• Structure
– Data and control flow, dependency graphs
– Structure and subsystem charts
– Architectures
• Implementation
– Symbol tables, source text

18. Different Approaches
• Restructuring
– Transformation from one representation to
another at the same level,
Requirements
Design
Source code
Behavior

19. Different Approaches
• Reverse Engineering
– Design Recovery
• reproduce all the info for understanding the system
– Re-documentation
• provide different views of the system
• Re-Engineering
– first phase --understanding the system
– second phase--forward engineering

20. Reverse Engineering Tools
• Analysis Tools
• Browsers
• Object Server
• Task Oriented Tools

21. Conclusions
• Reverse Engineering is a new research area
among software maintenance
• RE includes activities of understanding the
system and recovery info from system
• Program understanding is the most important
subset of Reverse Engineering
• Discovery of abstraction is key issue