Software reengineering in Software Engineering - Step-by-Step Execution

Concept Flow - Software reengineering

Identify Old Software

↓

Analyze Current System

↓

Plan Reengineering Approach

↓

Reverse Engineering

↓

Restructuring / Redocumentation

↓

Forward Engineering / Redevelopment

↓

Testing & Validation

↓

Deploy Updated Software

↓

End

This flow shows the main steps in software reengineering from identifying old software to deploying the updated version.

Execution Sample

Software Engineering

1. Identify old software needing improvement
2. Analyze its structure and problems
3. Plan how to improve or rewrite parts
4. Extract design info (reverse engineering)
5. Restructure or rewrite code
6. Test and deploy improved software

This sequence outlines the key actions taken during software reengineering.

Analysis Table

Step	Action	Purpose	Result
1	Identify old software	Find software needing update	Software selected for reengineering
2	Analyze current system	Understand existing design and issues	Documentation of current state
3	Plan reengineering approach	Decide what to improve and how	Reengineering strategy created
4	Reverse engineering	Extract design and requirements	Design models and documentation produced
5	Restructuring / Redocumentation	Improve code structure without changing behavior	Cleaner, easier to maintain code
6	Forward engineering / Redevelopment	Rewrite or add new features	Updated or new software components
7	Testing & Validation	Ensure software works correctly	Verified software ready for use
8	Deploy updated software	Release improved software to users	Software in production
9	End	Process complete	Software reengineering finished

💡 All steps completed, software is improved and deployed

State Tracker

Variable	Start	After Step 2	After Step 4	After Step 6	Final
Software State	Old and problematic	Analyzed and documented	Design extracted	Code restructured and rewritten	Tested and deployed

Key Insights - 3 Insights

Why do we do reverse engineering before rewriting code?

Reverse engineering helps us understand the existing software design and requirements (see execution_table step 4), so we can plan improvements accurately.

Is restructuring the same as rewriting the software?

No, restructuring improves the internal code structure without changing behavior (step 5), while rewriting (forward engineering) may add or change features (step 6).

Why is testing important after reengineering?

Testing (step 7) ensures that the improved software works correctly and meets requirements before deployment, preventing new errors.

Visual Quiz - 3 Questions

Look at the execution_table, what is the result after step 4 (Reverse engineering)?

A Software deployed to users

B Design models and documentation produced

C Code rewritten with new features

D Old software identified

💡 Hint

Check the 'Result' column for step 4 in the execution_table

At which step does the software get tested and validated?

A Step 7

B Step 5

C Step 3

D Step 2

💡 Hint

Look for 'Testing & Validation' in the 'Action' column of the execution_table

If we skip restructuring, which step would be missing from the execution_table?

A Step 6

B Step 4

C Step 5

D Step 7

💡 Hint

Restructuring is described in step 5 under 'Action' in the execution_table

Concept Snapshot

Software reengineering improves old software by analyzing, restructuring, and rewriting it.
Key steps: Identify, Analyze, Reverse engineer, Restructure, Redevelop, Test, Deploy.
Reverse engineering extracts design info.
Restructuring cleans code without changing behavior.
Testing ensures quality before release.

Full Transcript

Software reengineering is the process of improving existing software by first identifying the software that needs improvement, then analyzing its current structure and problems. Next, a plan is made on how to improve or rewrite parts of the software. Reverse engineering is used to extract design and requirement information from the existing software. After that, restructuring or redocumentation improves the code structure without changing its behavior. Forward engineering or redevelopment rewrites or adds new features. Testing and validation ensure the software works correctly. Finally, the updated software is deployed to users. This process helps keep software useful and maintainable over time.

Practice

1. What is the main goal of software reengineering?

easy

A. To create new software from scratch

B. To increase the number of software users

C. To delete outdated software permanently

D. To improve old software for easier maintenance and extension

Solution

1. Step 1: Understand the purpose of software reengineering

   Software reengineering focuses on improving existing software, not creating new software or deleting it.

2. Step 2: Identify the main benefit

   The main benefit is making old software easier to maintain and extend.

3. Final Answer:

   To improve old software for easier maintenance and extension -> Option D

4. Quick Check:

   Software reengineering = Improve old software [OK]

Hint: Focus on improving existing software, not creating new [OK]

Common Mistakes:

• Confusing reengineering with new software development
• Thinking it means deleting software
• Assuming it increases user base directly

2. Which of the following is a common step in software reengineering?

easy

A. Analyzing and restructuring existing code

B. Writing new software without reviewing old code

C. Deleting all old documentation

D. Ignoring software bugs

Solution

1. Step 1: Identify typical reengineering activities

   Reengineering involves analyzing and restructuring existing code to improve it.

2. Step 2: Eliminate incorrect options

   Writing new software without review, deleting documentation, or ignoring bugs are not part of reengineering.

3. Final Answer:

   Analyzing and restructuring existing code -> Option A

4. Quick Check:

   Reengineering step = Analyze and restructure code [OK]

Hint: Look for options about improving existing code [OK]

Common Mistakes:

• Choosing options about creating new software
• Ignoring the importance of analysis
• Confusing reengineering with software removal

3. Consider a software system that is outdated but still valuable. Which reengineering approach is most suitable?

medium

A. Software reverse engineering and restructuring

B. Complete rewrite from scratch

C. Ignoring the system and building a new one

D. Deleting the system immediately

Solution

1. Step 1: Understand the system condition

   The system is outdated but valuable, so it should be improved, not discarded.

2. Step 2: Choose the best reengineering approach

   Reverse engineering and restructuring help understand and improve the existing system without starting over.

3. Final Answer:

   Software reverse engineering and restructuring -> Option A

4. Quick Check:

   Outdated but valuable = Reverse engineering [OK]

Hint: Use reverse engineering for valuable outdated software [OK]

Common Mistakes:

• Choosing complete rewrite which is costly
• Ignoring the system instead of improving
• Deleting valuable software

4. A developer tries to reengineer software but skips analyzing the existing code. What is the likely problem?

medium

A. The software will be deleted

B. The reengineering will miss important design issues

C. The software will run faster without analysis

D. The software will automatically improve

Solution

1. Step 1: Understand the role of code analysis in reengineering

   Analyzing existing code helps find design problems and areas to improve.

2. Step 2: Predict consequences of skipping analysis

   Without analysis, important issues remain hidden, causing poor reengineering results.

3. Final Answer:

   The reengineering will miss important design issues -> Option B

4. Quick Check:

   Skip analysis = Miss design issues [OK]

Hint: Never skip code analysis in reengineering [OK]

Common Mistakes:

• Assuming software improves automatically
• Thinking skipping analysis speeds software
• Confusing deletion with reengineering

5. You have a legacy software with duplicated code and outdated modules. Which reengineering strategy best improves maintainability?

hard

A. Adding more duplicated code for backup

B. Deleting all old modules without replacement

C. Refactoring duplicated code and modularizing outdated parts

D. Ignoring the code quality and adding new features

Solution

1. Step 1: Identify problems in legacy software

   Duplicated code and outdated modules reduce maintainability and increase errors.

2. Step 2: Choose reengineering strategy to improve maintainability

   Refactoring removes duplication and modularizing updates old parts, making maintenance easier.

3. Final Answer:

   Refactoring duplicated code and modularizing outdated parts -> Option C

4. Quick Check:

   Fix duplication + modularize = better maintainability [OK]

Hint: Refactor duplicates and modularize outdated code [OK]

Common Mistakes:

• Deleting modules without replacement
• Adding more duplicated code
• Ignoring code quality issues