Software Engineering" (BCA-403)-2024

Section-A (Very Short Answer Type Questions)

Each question requires a very short answer (not exceeding 75 words), and each carries 3 marks.

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1. Write a note on software maintenance.

Explanation:

Software maintenance refers to the process of modifying, updating, and improving software after its deployment to correct faults, improve performance, or adapt it to a changing environment. It includes:

• Corrective Maintenance: Fixing bugs and errors.
• Adaptive Maintenance: Modifying software due to changes in hardware or OS.
• Perfective Maintenance: Enhancing functionalities.
• Preventive Maintenance: Improving software for future stability.

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2. Explain advantages and disadvantages of software reuse.

Advantages of Software Reuse:

• Cost Reduction: Saves development costs by reusing existing components.
• Time-Saving: Speeds up development by avoiding redundant coding.
• Improved Quality: Reused components are already tested and stable.
• Standardization: Encourages the use of standard practices.

Disadvantages of Software Reuse:

• Compatibility Issues: Old components may not fit well with new software.
• Hidden Bugs: Existing components might have unresolved issues.
• Maintenance Complexity: Updating reused components can be difficult.

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3. Differentiate between functional and non-functional requirements.

Feature	Functional Requirements	Non-Functional Requirements
Definition	Defines what the system should do.	Defines how the system should perform.
Example	Login functionality, data processing.	Performance, security, scalability.
Scope	Related to core system functionalities.	Related to system quality attributes.
Testing	Verified through functional testing.	Verified through performance testing.

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4. Explain cyclomatic complexity.

Explanation:

Cyclomatic complexity is a software metric used to measure the complexity of a program by counting the number of independent execution paths. It is calculated using the formula:

$$V(G) = E - N + 2P$$

Where:

• E = Number of edges in the control flow graph.
• N = Number of nodes in the control flow graph.
• P = Number of connected components.

A higher cyclomatic complexity indicates a more complex code, making testing and maintenance harder.

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5. Describe the prototype model and its advantages.

Prototype Model Explanation:

The Prototype Model is a software development approach where an initial prototype (or working model) is built, tested, and refined until the final system meets the user’s requirements. It is iterative and user-centered.

Advantages:

• Early Feedback: Users can provide feedback before full development.
• Reduces Risk: Identifies issues early in the development cycle.
• Better Requirement Understanding: Helps clarify unclear requirements.
• Improved User Satisfaction: Users get a clearer idea of the final product.

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Section-B (Short Answer Type Questions)

👉 Note: Attempt any two out of three questions. Each answer should be within 200 words and carries 7.5 marks.

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6. Describe system specification. Describe software requirement specification.

System Specification:

A system specification is a document that outlines the hardware and software requirements, functionalities, and constraints of a system. It provides a detailed description of how a system should behave and what resources are required for its development and operation.

Key Components of System Specification:

1. Hardware Requirements – CPU, RAM, Storage, etc.
2. Software Requirements – OS, databases, frameworks.
3. Functional Specifications – System operations and interactions.
4. Performance Criteria – Speed, reliability, and efficiency.
5. Security & Compliance – Encryption, user roles, and permissions.

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Software Requirement Specification (SRS):

The Software Requirement Specification (SRS) document is a detailed description of a software system's intended functionalities and constraints. It is a crucial part of software engineering that helps developers and stakeholders understand system requirements clearly.

Key Components of SRS:

1. Introduction: Purpose, scope, and objectives of the software.
2. Functional Requirements: Features and functionalities of the software.
3. Non-Functional Requirements: Performance, security, usability, etc.
4. Interface Requirements: UI/UX design, API specifications.
5. Assumptions & Constraints: Limitations of the system.

Conclusion:

A system specification is broader and includes hardware, while an SRS focuses specifically on software requirements. Both documents play a critical role in ensuring successful software development.

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7. What are the differences between software design and project planning? Explain it.

Software Design vs. Project Planning

Feature	Software Design	Project Planning
Definition	The process of creating the architecture, components, and layout of a software system.	The process of defining tasks, timelines, resources, and goals for software development.
Focus	Structure and functionality of the software.	Scheduling, budgeting, risk management, and resource allocation.
Key Deliverables	UML diagrams, database schemas, module structures.	Gantt charts, project timelines, milestones.
Approach	Uses design patterns, architectures like MVC, layered design.	Uses project management techniques like Agile, Waterfall, Scrum.
Stakeholders	Software architects, developers, testers.	Project managers, stakeholders, clients.

Detailed Explanation:

• Software Design involves defining how the software will function, including data structures, algorithms, user interfaces, and system interactions. It ensures that the software is modular, scalable, and maintainable.
• Project Planning is a broader concept that involves organizing, scheduling, and tracking the entire development process. It ensures that deadlines are met, resources are efficiently utilized, and risks are managed.

Conclusion:

While software design focuses on how the system will work, project planning ensures that development happens in a structured and timely manner.

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 Question 8: "What do you mean by system testing? Explain any two system testing methods."

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Introduction to System Testing

System Testing is a crucial phase in the Software Testing Life Cycle (STLC) where the entire system is tested as a whole. It evaluates the functional and non-functional aspects of the software to ensure that it meets the specified requirements.

System testing is performed after integration testing and before user acceptance testing (UAT). It ensures that all modules work together seamlessly in a real-world environment.

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Importance of System Testing

System testing is essential because:
✔ Validates Software Functionality: Ensures that the software meets business and technical requirements.
✔ Detects Bugs Early: Helps identify defects before the software reaches users.
✔ Ensures Compatibility: Verifies that the software works across different platforms, operating systems, and devices.
✔ Improves Security: Checks for vulnerabilities and ensures data protection.
✔ Enhances Performance: Measures software efficiency under different conditions.

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Types of System Testing

System testing includes various testing techniques, each focusing on different aspects of software validation. Below are two commonly used system testing methods:

1. Functional Testing

Functional testing ensures that the software system performs its intended functions correctly. It is based on the functional requirements provided by the client.

Key Aspects of Functional Testing:

✅ Input Validation: Checks if the system processes valid and invalid inputs correctly.
✅ User Interface Testing: Ensures that UI elements work as expected.
✅ Database Testing: Validates data storage, retrieval, and integrity.
✅ Business Logic Testing: Confirms that calculations and workflows function correctly.

Example of Functional Testing:

Suppose an online banking application allows users to transfer money. A functional test would check:

• Whether the login system works correctly.
• If the user can select an account for transactions.
• If the transfer amount is deducted correctly from the sender’s account.
• Whether the confirmation message is displayed.

Advantages of Functional Testing:

✔ Ensures that the software meets user expectations.
✔ Identifies major defects early.
✔ Provides a better user experience by validating functionalities.

Disadvantages of Functional Testing:

❌ Does not test performance or security aspects.
❌ Requires detailed requirement specifications.

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2. Performance Testing

Performance testing evaluates how well the system performs under different conditions, including normal load, peak load, and stress conditions.

Key Aspects of Performance Testing:

✅ Load Testing: Determines how the system behaves under expected user load.
✅ Stress Testing: Pushes the system beyond its capacity to check for failure points.
✅ Scalability Testing: Examines if the software can handle increased workloads.
✅ Response Time Testing: Measures how fast the system processes user requests.

Example of Performance Testing:

Consider an e-commerce website that experiences high traffic during a sale. Performance testing would check:

• How the website behaves when 100,000 users access it simultaneously.
• Whether the system slows down or crashes.
• If response times increase beyond an acceptable limit (e.g., 2 seconds per request).

Advantages of Performance Testing:

✔ Ensures system stability and reliability under heavy traffic.
✔ Prevents server crashes during peak hours.
✔ Improves customer experience by ensuring fast response times.

Disadvantages of Performance Testing:

❌ Requires special tools like JMeter, LoadRunner, or Gatling.
❌ Can be expensive and time-consuming.

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System Testing vs. Other Testing Types

Feature	System Testing	Unit Testing	Integration Testing
Scope	Tests the entire system	Tests individual components	Tests interactions between modules
Performed By	Testers	Developers	Testers/Developers
Objective	Ensure system-wide functionality	Verify correctness of single module	Check data flow between modules
Example	Test login, search, checkout features	Test login validation logic	Test data passing from login to dashboard

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Challenges in System Testing

🔹 Complexity: Large software systems require extensive testing.
🔹 Time-Consuming: Running multiple tests for an entire system takes time.
🔹 Requirement Changes: If business needs change, tests may need to be rewritten.
🔹 Environment Issues: Differences between test and production environments can cause inconsistencies.

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Section-C (Long Answer Type Questions)

👉 Note: Attempt any three out of the five questions. Each answer requires a detailed explanation and carries 15 marks.

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9. What is a software process model? Explain the advantages and disadvantages of spiral and prototyping models.

Software Process Model

A Software Process Model is a structured framework that defines the processes and activities involved in software development. It guides software engineers in planning, designing, developing, testing, and maintaining software. Common process models include Waterfall, Agile, Spiral, and Prototyping models.

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Spiral Model

The Spiral Model, proposed by Barry Boehm, combines iterative development with risk analysis. It consists of four phases:

1. Planning: Requirements gathering and system objectives.
2. Risk Analysis: Identifying risks and exploring solutions.
3. Engineering: Development and testing of prototypes.
4. Evaluation: User feedback and refinement.

Advantages of the Spiral Model:

✔ Risk Management: Identifies and reduces risks at every phase.
✔ Flexibility: Changes can be made easily during development.
✔ Customer Involvement: Frequent feedback leads to better product quality.

Disadvantages of the Spiral Model:

❌ Complexity: Requires experienced risk management teams.
❌ Costly: More expensive due to iterative cycles.
❌ Time-Consuming: Lengthy due to multiple iterations.

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Prototyping Model

The Prototyping Model focuses on developing a preliminary version (prototype) of the software and refining it based on user feedback.

Advantages of the Prototyping Model:

✔ Better Requirement Understanding: Users can visualize and suggest improvements.
✔ Improved User Satisfaction: End-users get a system close to their needs.
✔ Early Defect Detection: Bugs and issues are fixed in early stages.

Disadvantages of the Prototyping Model:

❌ Scope Creep: Continuous changes can delay the project.
❌ High Development Cost: Creating multiple prototypes requires resources.
❌ Not Suitable for Large Projects: Complex projects require more structured models.

Conclusion:

The Spiral Model is ideal for risk-heavy projects, while the Prototyping Model works best when requirements are unclear.

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10. What do you understand by software reliability metrics? Explain the different types of software reliability metrics.

Software Reliability Metrics

Software reliability refers to the probability that a software system will function correctly under specific conditions for a defined period. Reliability metrics help in measuring the quality, performance, and stability of software.

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Types of Software Reliability Metrics

1. Mean Time Between Failures (MTBF)

• Measures the average time between software failures.
• Formula: $$MTBF = \frac{\text{Total uptime}}{\text{Number of failures}}$$
• Higher MTBF indicates a more reliable system.

2. Mean Time To Failure (MTTF)

• Similar to MTBF, but applies to non-repairable systems.
• Formula: $$MTTF = \frac{\text{Total operating time}}{\text{Total number of failures}}$$

3. Mean Time To Repair (MTTR)

• Measures the average time required to fix a failure.
• Formula: $$MTTR = \frac{\text{Total downtime}}{\text{Number of failures}}$$
• Lower MTTR means quicker recovery from failures.

4. Failure Rate

• Defines how often a system fails.
• Formula: $$\lambda = \frac{\text{Number of failures}}{\text{Total operational time}}$$
• Lower failure rate = more reliable software.

Conclusion:

Reliability metrics help in assessing system performance, ensuring minimal failures, and improving software quality.

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11. Explain different test strategies.

Test Strategies in Software Engineering

A test strategy is a high-level plan that outlines how software testing will be conducted. It includes objectives, tools, resources, and schedules for testing activities.

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Types of Test Strategies

1. Preventive Testing Strategy

• Focuses on early detection of defects during software design and development.
• Includes techniques like static testing, reviews, and walkthroughs.

2. Reactive Testing Strategy

• Testing is done after the software is developed.
• No pre-planning; based on user feedback and failures.

3. Analytical Testing Strategy

• Uses risk analysis to prioritize test cases.
• Example: Testing mission-critical components first.

4. Model-Based Testing Strategy

• Uses mathematical models to generate test cases.
• Example: Finite state machines and decision tables.

5. Agile Testing Strategy

• Used in Agile development (Scrum, Kanban).
• Continuous testing, automation, and collaboration.

Conclusion:

A good test strategy ensures efficient defect detection, improves software quality, and ensures a smooth user experience.

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Question 12: Discuss the concept of software maintenance process. Justify the statement "Software maintenance is costlier."

Introduction to Software Maintenance

Software Maintenance is the process of modifying, updating, and improving software after its deployment to correct errors, enhance performance, or adapt to new environments. It ensures that the software remains functional and relevant throughout its lifecycle.

Once a software application is released, it requires continuous maintenance to address bugs, security threats, performance issues, and changing user requirements.

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Types of Software Maintenance

Software maintenance can be categorized into four types:

1. Corrective Maintenance

• Involves fixing defects, errors, or faults found in the software after deployment.
• Example: If a banking application crashes while processing a transaction, corrective maintenance is required to fix the issue.

2. Adaptive Maintenance

• Adjusting the software to new environments, operating systems, or hardware.
• Example: A mobile application might need updates to work on the latest version of Android or iOS.

3. Perfective Maintenance

• Enhancing the software by adding new features or improving performance.
• Example: A social media app introducing a dark mode feature based on user feedback.

4. Preventive Maintenance

• Aims at reducing future failures by restructuring the software code and improving security.
• Example: Implementing security patches to protect a system from cyber threats.

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Why is Software Maintenance Costly?

The statement "Software maintenance is costlier" is true because maintenance requires continuous updates, bug fixes, and improvements. The following factors contribute to the high cost of software maintenance:

1. Complexity of Software Systems

• Modern software applications have thousands of lines of code, making debugging and modifying the software difficult.
• Developers must ensure that new changes do not introduce unexpected bugs.

2. Changing User Requirements

• Over time, users demand new features and functionalities.
• Implementing these changes requires significant development efforts.

3. Backward Compatibility

• Updates should not affect the existing users negatively.
• Maintaining compatibility with older hardware, software versions, or databases adds cost.

4. Security and Compliance Costs

• Organizations must continuously update security patches to protect against cyber threats.
• Compliance with industry standards (e.g., GDPR, HIPAA) also adds to the maintenance cost.

5. Skilled Workforce Requirement

• Hiring experienced developers and testers for maintenance is expensive.
• Debugging and enhancing a system requires deep technical knowledge.

6. Continuous Testing and Monitoring

• Every update requires regression testing to ensure that the new changes do not break existing functionality.
• Tools like Jenkins, Selenium, and JIRA add to the maintenance expenses.

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Example Case Study: Microsoft Windows

• Windows OS receives frequent security updates and feature enhancements.
• Microsoft invests billions of dollars in maintaining Windows across different devices and ensuring compatibility with newer hardware.
• This proves that software maintenance is more expensive than initial development.

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Conclusion

Software maintenance is essential to keep applications running smoothly and securely. However, due to the complexity, security needs, and evolving user demands, maintenance costs are often higher than initial development. Organizations must plan their software lifecycle properly to manage maintenance expenses efficiently.

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Question 13: Explain the following:

(i) Quality Assurance (QA)

(ii) Software Cost Estimation

(iii) Test Planning

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(i) Quality Assurance (QA)

Definition

Quality Assurance (QA) is a process that ensures software meets specified quality standards before being released to users. QA focuses on preventing defects rather than detecting them after development.

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Objectives of QA:

✅ Ensure software meets customer expectations.
✅ Prevent errors and defects before deployment.
✅ Improve software reliability, security, and performance.

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QA Activities:

1. Requirement Analysis: Ensuring clear and well-defined requirements.
2. Code Reviews: Inspecting the code for errors before testing.
3. Testing Procedures: Implementing unit testing, integration testing, and system testing.
4. Process Improvement: Continuous refinement of development processes.

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Example of QA in Action:

A healthcare application needs to comply with strict regulations to protect patient data. The QA team ensures that the software meets security and compliance standards before release.

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(ii) Software Cost Estimation

Definition

Software Cost Estimation is the process of predicting the time, effort, and resources required for software development.

Importance of Cost Estimation

✔ Helps in budget planning and resource allocation.
✔ Reduces the risk of project delays and cost overruns.
✔ Ensures that clients have realistic expectations about software delivery.

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Methods of Software Cost Estimation

1. COCOMO Model (Constructive Cost Model)
   • Estimates cost based on size, complexity, and effort required.
2. Function Point Analysis (FPA)
   • Measures software size based on functional requirements.
3. Expert Judgment Method
   • Relies on experience from past projects to estimate costs.

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Example:

A company planning to develop an e-commerce website must estimate costs for:

• Web development, payment gateways, security features, and maintenance.
• Using the COCOMO model, the project manager can estimate development costs accurately.

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(iii) Test Planning

Definition

Test Planning is the process of defining a strategy, scope, objectives, schedule, and resources for testing a software application.

Key Components of a Test Plan:

✅ Test Objectives: Define what needs to be tested.
✅ Scope: Identify the functionalities covered in testing.
✅ Test Environment: Specify hardware, software, and network configurations.
✅ Test Cases: Design test cases for different scenarios.
✅ Risk Analysis: Identify potential risks and mitigation strategies.

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Test Planning Process:

1. Requirement Analysis: Understanding business needs.
2. Test Strategy Definition: Selecting manual or automated testing.
3. Test Case Design: Creating test scripts and test data.
4. Execution & Reporting: Running tests and logging defects.

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Example of Test Planning in Action

A mobile banking app requires test planning to ensure:

• Secure login authentication.
• Transaction processing without errors.
• Performance under high user traffic.

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Conclusion

• Quality Assurance (QA) ensures that software meets high-quality standards.
• Software Cost Estimation helps in planning budgets and resources.
• Test Planning ensures thorough and structured testing, leading to a stable product.

These concepts are essential for building reliable, cost-effective, and high-performance software applications.

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