Software Engineering (4353202) - Winter 2024 Solution

Question 1(a) [3 marks]

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Define software and explain its characteristics.

Answer:

Software is a collection of computer programs, procedures, and documentation that performs tasks on a computer system.

Table: Software Characteristics

• Key point: Software = Programs + Documentation + Procedures
• Mnemonic: “I Don’t Make Reliable Electronics” (Intangible, Developed, Maintainable, Reliable, Efficient)

Question 1(b) [4 marks]

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Explain classical waterfall model.

Answer:

Waterfall Model is a linear sequential software development approach where each phase must be completed before the next begins.

graph TD
    A[Requirements Analysis] --> B[System Design]
    B --> C[Implementation]
    C --> D[Testing]
    D --> E[Deployment]
    E --> F[Maintenance]

Key Features:

• Sequential phases: No overlap between phases
• Documentation-driven: Heavy documentation at each phase
• Simple structure: Easy to understand and manage
• Fixed requirements: Changes are difficult once started

Mnemonic: “Real Systems Include Testing, Deployment, Maintenance”

Question 1(c) [7 marks]

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Explain software process framework and umbrella activities.

Answer:

Software Process Framework provides the foundation for complete software engineering process by identifying key process areas.

graph LR
    A[Communication] --> B[Planning]
    B --> C[Modeling]
    C --> D[Construction]
    D --> E[Deployment]
    E --> A
    
    F[Umbrella Activities] --> A
    F --> B
    F --> C
    F --> D
    F --> E

Table: Framework Activities vs Umbrella Activities

Framework Activities:

• Communication: Gather requirements from stakeholders
• Planning: Create project plan and schedule
• Modeling: Create design models
• Construction: Code generation and testing
• Deployment: Software delivery and feedback

Umbrella Activities run throughout the project:

• Project tracking: Monitor progress
• Risk management: Identify and control risks
• Quality assurance: Ensure quality standards
• Configuration management: Control changes

Mnemonic: “Can People Make Construction Deploy” (Communication, Planning, Modeling, Construction, Deployment)

Question 1(c) OR [7 marks]

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Write a short note on SCRUM.

Answer:

SCRUM is an agile framework for managing software development projects using iterative and incremental practices.

graph TD
    A[Product Backlog] --> B[Sprint Planning]
    B --> C[Sprint Backlog]
    C --> D[Sprint 2-4 weeks]
    D --> E[Sprint Review]
    E --> F[Sprint Retrospective]
    F --> B
    D --> G[Daily Scrum]
    G --> D

Table: SCRUM Roles and Artifacts

Key Events:

• Sprint Planning: Select work for upcoming sprint
• Daily Scrum: 15-minute daily synchronization
• Sprint Review: Demonstrate completed work
• Sprint Retrospective: Reflect and improve process

Benefits: Fast delivery, flexibility, continuous improvement, customer collaboration

Mnemonic: “People Sprint Daily Reviewing Retrospectively”

Question 2(a) [3 marks]

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Explain characteristic of good SRS.

Answer:

SRS (Software Requirements Specification) document should have specific qualities to be effective.

Table: Good SRS Characteristics

• Complete: Contains all functional and non-functional requirements
• Consistent: No conflicts between different requirements
• Unambiguous: Each requirement has only one interpretation

Mnemonic: “Complete Computers Use Verified Modifications”

Question 2(b) [4 marks]

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Describe advantage and disadvantages of prototype model.

Answer:

Prototype Model creates a working model of software to understand requirements better.

Table: Prototype Model - Pros and Cons

Advantages:

• Clear requirements: Users see working model
• Early feedback: Reduces final product risks
• User involvement: Better user acceptance

Disadvantages:

• Extra time: Building prototype takes time
• Additional cost: Resources needed for prototype
• Scope creep: Users may expect prototype features

Mnemonic: “Better Users Experience” vs “Time Costs Increase”

Question 2(c) [7 marks]

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Design and describe Spiral model and give advantages and disadvantages.

Answer:

Spiral Model combines iterative development with systematic risk management through repeated cycles.

graph TD
    A[Planning] --> B[Risk Analysis]
    B --> C[Engineering]
    C --> D[Customer Evaluation]
    D --> A
    
    E[Quadrant 1: Planning] 
    F[Quadrant 2: Risk Analysis]
    G[Quadrant 3: Engineering]
    H[Quadrant 4: Customer Evaluation]

Table: Spiral Model Phases

Advantages:

• Risk management: Early risk identification
• Flexibility: Accommodates changes easily
• Customer involvement: Regular customer feedback
• Quality focus: Continuous testing and validation

Disadvantages:

• Complex management: Difficult to manage
• High cost: Expensive due to risk analysis
• Time consuming: Long development cycles
• Risk expertise needed: Requires risk assessment skills

Best for: Large, complex, high-risk projects

Mnemonic: “Plan Risks Engineering Customer” for phases

Question 2(a) OR [3 marks]

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Explain Incremental model.

Answer:

Incremental Model delivers software in small, functional pieces called increments.

graph LR
    A[Core Product] --> B[Increment 1]
    B --> C[Increment 2]
    C --> D[Increment 3]
    D --> E[Final Product]

Key Features:

• Partial implementation: Each increment adds functionality
• Early delivery: Core features delivered first
• Parallel development: Multiple increments can be developed simultaneously

Table: Incremental Model Characteristics

Mnemonic: “Deliver Functionality Reducing Feedback”

Question 2(b) OR [4 marks]

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Write concept of Rapid Application Development model and explain it.

Answer:

RAD (Rapid Application Development) emphasizes rapid prototyping and quick feedback over extensive planning.

Table: RAD Model Phases

Key Concepts:

• Reusable components: Pre-built components speed development
• Powerful tools: CASE tools and code generators
• Small teams: 2-6 people per team
• Time-boxed: Strict time limits (60-90 days)

Requirements for RAD:

• Well-defined business requirements
• User involvement throughout process
• Skilled developers familiar with RAD tools

Mnemonic: “Business Data Process Application Testing”

Question 2(c) OR [7 marks]

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Define SDLC and explain each phase.

Answer:

SDLC (Software Development Life Cycle) is a systematic process for building software through well-defined phases.

graph TD
    A[Planning] --> B[Analysis]
    B --> C[Design]
    C --> D[Implementation]
    D --> E[Testing]
    E --> F[Deployment]
    F --> G[Maintenance]
    G --> A

Table: SDLC Phases Detailed

Phase Descriptions:

• Planning: Define project scope and resources
• Analysis: Understand what system should do
• Design: Plan how system will work
• Implementation: Build the actual system
• Testing: Verify system works correctly
• Deployment: Release system to users
• Maintenance: Ongoing support and updates

Mnemonic: “People Always Design Implementation, Test Deployment, Maintain”

Question 3(a) [3 marks]

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Describe skills to manage software projects.

Answer:

Software Project Management requires combination of technical and soft skills.

Table: Essential Project Management Skills

Key Skills:

• People management: Lead and motivate team members
• Technical knowledge: Understand development process and tools
• Communication: Bridge between technical team and stakeholders

Mnemonic: “Technical Leaders Communicate Planning Problems”

Question 3(b) [4 marks]

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Briefly write responsibility of Software Project manager.

Answer:

Software Project Manager oversees entire project from initiation to completion.

Table: Project Manager Responsibilities

Primary Responsibilities:

• Project Planning: Define scope, timeline, and resources
• Team Leadership: Guide and support development team
• Stakeholder Communication: Keep everyone informed of progress
• Quality Assurance: Ensure project meets requirements
• Risk Management: Handle project risks and issues

Success Factors: On-time delivery, within budget, meeting requirements

Mnemonic: “Plan Team Communication Quality Risk”

Question 3(c) [7 marks]

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Classify types of Requirements in SRS (1) Functional Requirements (2) Non-Functional Requirements.

Answer:

Requirements Classification helps organize and understand different types of system needs.

Table: Functional vs Non-Functional Requirements

Functional Requirements:

• User interactions: Login, registration, data entry
• Business rules: Validation rules, calculations
• System features: Reports, notifications, workflows
• Data processing: CRUD operations

Examples:

• User can login with username/password
• System calculates tax automatically
• Generate monthly sales report

Non-Functional Requirements:

Table: Non-Functional Requirement Types

Quality Attributes:

• Performance: Response time, throughput
• Security: Authentication, authorization, encryption
• Usability: User-friendly interface, accessibility
• Reliability: Uptime, error handling
• Maintainability: Code quality, documentation

Mnemonic: “Performance Security Usability Reliability Maintainability”

Question 3(a) OR [3 marks]

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Illustrate importance of SRS.

Answer:

SRS (Software Requirements Specification) is crucial document that defines what software should do.

Table: SRS Importance

Key Importance:

• Communication tool: Bridge between clients and developers
• Planning foundation: Helps estimate time, cost, and resources
• Testing basis: Test cases derived from SRS requirements

Mnemonic: “Clear Planning Quality Change Legal”

Question 3(b) OR [4 marks]

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Explain Gantt Chart.

Answer:

Gantt Chart is a visual project management tool showing tasks, timelines, and dependencies.

gantt
    title Project Schedule
    dateFormat  YYYY-MM-DD
    section Phase 1
    Requirements    :a1, 2024-01-01, 30d
    Design         :a2, after a1, 20d
    section Phase 2
    Coding         :a3, after a2, 45d
    Testing        :a4, after a3, 15d

Table: Gantt Chart Components

Benefits:

• Visual timeline: Easy to see project schedule
• Progress tracking: Monitor task completion
• Resource planning: Allocate resources effectively
• Dependency management: Understand task relationships

Mnemonic: “Tasks Timeline Bars Dependencies Milestones”

Question 3(c) OR [7 marks]

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Write a short note on Risk Management.

Answer:

Risk Management is systematic process of identifying, analyzing, and controlling project risks.

graph TD
    A[Risk Identification] --> B[Risk Analysis]
    B --> C[Risk Planning]
    C --> D[Risk Monitoring]
    D --> A

Table: Risk Management Process

Risk Categories:

Table: Types of Software Risks

Risk Response Strategies:

• Avoid: Eliminate risk source
• Mitigate: Reduce probability or impact
• Transfer: Share risk with others
• Accept: Live with the risk

Risk Assessment: Probability × Impact = Risk Exposure

Benefits: Proactive problem solving, better project success rate, stakeholder confidence

Mnemonic: “Identify Analyze Plan Monitor” for process, “Avoid Mitigate Transfer Accept” for strategies

Question 4(a) [3 marks]

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What is metric for size estimation? Explain FP with example.

Answer:

Size Estimation Metrics help predict software project size and effort.

Table: Size Estimation Metrics

Function Points (FP) measure software size based on user functionality.

FP Components:

• External Inputs: Data entry screens
• External Outputs: Reports, messages
• External Queries: Database queries
• Internal Files: Data stores
• External Interfaces: System connections

FP Calculation Example: For a Library Management System:

• External Inputs: 5 (Book entry, Member entry, etc.)
• External Outputs: 3 (Reports)
• External Queries: 4 (Search functions)
• Internal Files: 2 (Book DB, Member DB)
• External Interfaces: 1 (Online catalog)

Simple FP = 5 + 3 + 4 + 2 + 1 = 15 Function Points

Mnemonic: “Inputs Outputs Queries Files Interfaces”

Question 4(b) [4 marks]

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Explain project estimation techniques using basic COCOMO model.

Answer:

COCOMO (COnstructive COst MOdel) estimates software development effort and schedule.

Table: COCOMO Model Types

Basic COCOMO Formula:

• Effort = a × (KLOC)^b person-months
• Time = c × (Effort)^d months
• People = Effort / Time

Table: COCOMO Constants

Example: For 10 KLOC organic project

• Effort = 2.4 × (10)^1.05 = 25.47 person-months
• Time = 2.5 × (25.47)^0.38 = 8.64 months
• People = 25.47 / 8.64 = 3 people

Mnemonic: “Organic Semi Embedded” for project types

Question 4(c) [7 marks]

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Prepare Sprint burn down chart for system of your choice.

Answer:

Sprint Burn Down Chart tracks remaining work during a sprint for Online Shopping System.

graph LR
    A[Sprint Goal: User Authentication Module<br/>Sprint Duration: 2 weeks<br/>Total Story Points: 40]

Sprint Backlog:

Table: Sprint Tasks

Burn Down Chart Data:

Table: Daily Progress

Chart Analysis:

• Green line: Ideal burn down
• Red line: Actual progress
• Variations: Show challenges and recoveries
• Completion: Sprint finished on time

Benefits: Visual progress tracking, early problem identification, team motivation

Mnemonic: “Track Progress Daily, Identify Issues Early”

Question 4(a) OR [3 marks]

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Explain the component of USE CASE diagram.

Answer:

Use Case Diagram shows system functionality from user perspective.

Table: Use Case Diagram Components

Relationships:

• Include: One use case includes another (mandatory)
• Extend: Optional use case extension
• Generalization: Parent-child relationship

Example Components:

• Primary Actor: Customer, Admin
• Use Cases: Login, Search Products, Place Order
• System: Online Shopping System

Mnemonic: “Actors Use Systems, Associate Generally”

Question 4(b) OR [4 marks]

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Compare Cohesion and Coupling.

Answer:

Cohesion and Coupling are important software design principles affecting maintainability.

Table: Cohesion vs Coupling Comparison

Cohesion Types (Low to High):

• Coincidental: Random grouping
• Logical: Similar logic
• Temporal: Same time execution
• Procedural: Sequential steps
• Communicational: Same data
• Sequential: Output of one is input of next
• Functional: Single purpose

Coupling Types (High to Low):

• Content: Direct access to module internals
• Common: Shared global data
• External: Shared external interface
• Control: Control information passed
• Stamp: Data structure passed
• Data: Simple data passed

Goal: High Cohesion + Low Coupling = Good Design

Mnemonic: “High Cohesion, Low Coupling” for good design

Question 4(c) OR [7 marks]

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Explain Risk Assessment in detail.

Answer:

Risk Assessment evaluates identified risks to prioritize management efforts.

graph TD
    A[Risk Identification] --> B[Risk Assessment]
    B --> C[Probability Analysis]
    B --> D[Impact Analysis]
    C --> E[Risk Exposure Calculation]
    D --> E
    E --> F[Risk Prioritization]

Risk Assessment Components:

Table: Risk Assessment Elements

Assessment Process:

1. Probability Assessment:

• Very Low (0.1): Unlikely to happen
• Low (0.3): Possible but not probable
• Medium (0.5): May or may not happen
• High (0.7): Likely to happen
• Very High (0.9): Almost certain

2. Impact Assessment:

• Catastrophic (9-10): Project failure
• Critical (7-8): Major delays/cost overrun
• Marginal (4-6): Some impact on schedule/budget
• Negligible (1-3): Little impact

3. Risk Exposure Calculation: Risk Exposure = Probability × Impact

Example Risk Assessment:

Table: Sample Risk Analysis

Risk Matrix:

• High Priority: Exposure > 4.0
• Medium Priority: Exposure 2.0-4.0
• Low Priority: Exposure < 2.0

Assessment Benefits:

• Objective prioritization: Data-driven decisions
• Resource allocation: Focus on high-risk items
• Communication tool: Clear risk communication
• Planning input: Influences project planning

Mnemonic: “Probability Impact Exposure Priority”

Question 5(a) [3 marks]

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Explain code inspection technique in code review.

Answer:

Code Inspection is formal, systematic examination of code to find defects.

Table: Code Inspection Process

Key Features:

• Formal process: Structured approach with defined roles
• Systematic review: Line-by-line examination
• Defect focused: Find errors, not solutions
• No author criticism: Focus on code, not coder

Benefits: Early defect detection, knowledge sharing, improved code quality

Mnemonic: “Plan Overview Prepare Inspect Rework Follow-up”

Question 5(b) [4 marks]

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Prepare at least four test cases of ATM.

Answer:

ATM Test Cases verify automated teller machine functionality.

Table: ATM Test Cases

Detailed Test Cases:

Test Case 1: Valid Login

• Precondition: ATM is operational, card inserted
• Steps: Enter correct PIN → Press Enter
• Expected: Main menu with options displayed

Test Case 2: Cash Withdrawal

• Precondition: User logged in, sufficient balance
• Steps: Select Withdrawal → Enter amount → Confirm
• Expected: Cash dispensed, balance updated

Test Case 3: Balance Inquiry

• Precondition: User logged in
• Steps: Select Balance Inquiry
• Expected: Current balance displayed on screen

Test Case 4: PIN Change

• Precondition: User logged in
• Steps: Select Change PIN → Enter old PIN → Enter new PIN → Confirm
• Expected: PIN changed successfully, confirmation message

Mnemonic: “Login Withdraw Inquiry Change”

Question 5(c) [7 marks]

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Describe white box testing.

Answer:

White Box Testing examines internal code structure and logic paths.

graph TD
    A[Source Code] --> B[Control Flow Analysis]
    B --> C[Path Coverage]
    C --> D[Test Case Design]
    D --> E[Test Execution]
    E --> F[Coverage Analysis]

Table: White Box Testing Characteristics

Coverage Criteria:

Table: Coverage Types

White Box Testing Techniques:

1. Basis Path Testing:

• Calculate Cyclomatic Complexity: V(G) = E - N + 2
• E = Edges, N = Nodes in control flow graph
• Generate independent paths equal to V(G)

2. Loop Testing:

• Simple loops: Test 0, 1, 2, typical, max iterations
• Nested loops: Test inner loop first, then outer
• Concatenated loops: Test as separate loops

3. Condition Testing:

• Test all logical conditions (AND, OR, NOT)
• Ensure each condition evaluates to true and false

Example: Simple Code Testing

if (age >= 18 AND income > 25000)
    approve_loan();
else
    reject_loan();

Test Cases:

• age=20, income=30000 (both true) → approve
• age=16, income=30000 (first false) → reject
• age=20, income=20000 (second false) → reject
• age=16, income=20000 (both false) → reject

Advantages:

• Thorough testing: Tests internal logic
• Early defect detection: Finds logic errors
• Coverage measurement: Quantifiable testing progress

Disadvantages:

• Time consuming: Requires code knowledge
• Expensive: Needs skilled testers
• Maintenance: Changes with code updates

Tools: JUnit (Java), NUnit (.NET), Coverage.py (Python)

Mnemonic: “Statement Branch Path Condition” for coverage types

Question 5(a) OR [3 marks]

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Explain code walk through Technique in code review.

Answer:

Code Walk Through is informal code review technique where author presents code to team.

Table: Walk Through Process

Key Characteristics:

• Author-led: Code author drives the session
• Informal process: Less structured than inspection
• Educational: Team learns about code functionality
• Collaborative: Open discussion encouraged

Participants:

• Author: Presents and explains code
• Reviewers: Ask questions and provide feedback
• Moderator: Keeps discussion focused (optional)

Benefits: Knowledge sharing, early problem detection, team collaboration, learning opportunity

Mnemonic: “Prepare Present Discuss Document”

Question 5(b) OR [4 marks]

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Explain software documentation.

Answer:

Software Documentation provides information about software system for various stakeholders.

Table: Documentation Types

Internal Documentation:

• Code comments: Explain complex logic
• Function headers: Describe purpose and parameters
• Variable names: Self-documenting identifiers
• README files: Project overview and setup

External Documentation:

• User manuals: Step-by-step usage instructions
• Installation guides: Setup procedures
• API documentation: Interface specifications
• Training materials: Educational content

Benefits:

• Maintainability: Easier code updates
• Knowledge transfer: New team members learn faster
• User support: Reduces support requests
• Quality assurance: Documents requirements and design

Documentation Standards: Consistent format, regular updates, version control, accessibility

Mnemonic: “User System Process Requirements” for types

Question 5(c) OR [7 marks]

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Write a short note on black box testing.

Answer:

Black Box Testing examines software functionality without knowledge of internal code structure.

graph LR
    A[Input] --> B[Software System<br/>Black Box] --> C[Output]
    D[Test Cases] --> A
    E[Expected Results] --> F[Compare]
    C --> F

Table: Black Box Testing Characteristics

Black Box Testing Techniques:

Table: Testing Techniques

1. Equivalence Partitioning:

• Valid partitions: Accepted inputs
• Invalid partitions: Rejected inputs
• Test one value from each partition

Example: Password length (6-12 characters)

• Valid: 6-12 characters
• Invalid: <6 characters, >12 characters

2. Boundary Value Analysis:

• Test minimum, maximum, just below minimum, just above maximum
• Most errors occur at boundaries

Example: For range 1-100

• Test: 0, 1, 2, 99, 100, 101

3. Decision Table Testing:

• Conditions: Input conditions
• Actions: Expected outputs
• Rules: Condition-action combinations

Advantages:

• User perspective: Tests from user viewpoint
• No code knowledge needed: Testers don’t need programming skills
• Unbiased: Not influenced by code implementation
• Early testing: Can start with requirements

Disadvantages:

• Limited coverage: May miss some code paths
• Redundant testing: Might test same logic multiple times
• Difficult test case design: Hard without internal knowledge

Types of Black Box Testing:

• Functional Testing: Core functionality
• Non-functional Testing: Performance, usability
• Regression Testing: After changes
• User Acceptance Testing: Final validation

Tools: Selenium (web), Appium (mobile), TestComplete, QTP

When to Use:

• System testing phase
• User acceptance testing
• Integration testing
• Regression testing

Mnemonic: “Equivalence Boundary Decision State” for techniques