Unit-2 Part 1
1. What are the common methods used for size estimation in software projects, and how do Lines of Code (LOC) and Function Point count differ?
Answer:
Common size estimation methods include Lines of Code (LOC) and Function Point Analysis (FPA).
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LOC measures the total number of lines in the source code. It is easy to calculate but language-dependent and doesn’t capture complexity well.
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Function Point count measures the functionality delivered to the user, independent of technology or coding language. It counts inputs, outputs, user interactions, files, and interfaces.
Example:
For a payroll software, LOC might be 10,000 lines in Java, while function points would measure the number of functions like "Calculate Salary," "Generate Payslip," etc., providing a more technology-agnostic estimate.
2. Explain the basic idea behind cost estimation models in software engineering. Why are they important?
Answer:
Cost estimation models predict the amount of effort, time, and resources needed to complete a software project based on size, complexity, and other factors. They help in budgeting, scheduling, and resource allocation.
Example:
Before starting a mobile banking app, cost estimation models can help the bank decide how much budget and time to allocate, avoiding underestimation that might cause delays or cost overruns.
3. Describe the COCOMO model and how it is used to estimate software project effort.
Answer:
COCOMO (Constructive Cost Model) estimates effort (person-months) based on the size of the software (usually in KLOC). It uses mathematical formulas with coefficients based on project type (organic, semi-detached, embedded).
Example:
For an embedded system with 50 KLOC, COCOMO estimates effort using a formula like Effort = a * (KLOC)^b, where 'a' and 'b' depend on project type, giving a project manager an idea of required manpower.
4. What are the main differences between the Basic, Intermediate, and Detailed COCOMO models?
Answer:
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Basic COCOMO: Estimates effort based on size alone (KLOC) using simple formulas.
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Intermediate COCOMO: Adds cost drivers like product complexity, team experience, and tools to adjust the effort.
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Detailed COCOMO: Further breaks down the project into phases (design, coding, testing) and applies cost drivers to each phase.
Example:
Developing a business application: Basic COCOMO gives a rough estimate; Intermediate adjusts for experienced staff and tool usage; Detailed models the effort per phase like design and testing separately.
5. How does the Putnam resource allocation model help in planning software project schedules?
Answer:
The Putnam model uses software size, development time, and productivity to allocate resources optimally over time, emphasizing the trade-off between staff size and schedule duration. It helps avoid overstaffing or underutilization.
Example:
A software firm developing an e-commerce platform uses the Putnam model to decide how many developers are needed each month to complete the project on schedule without burnout.
6. What is the significance of validating software estimates, and what techniques can be used to validate them?
Answer:
Validating estimates ensures accuracy and feasibility, reducing risks of budget overruns and missed deadlines. Techniques include expert judgment, analogy with past projects, and prototype testing.
Example:
Before launching a new social media app, the team compares the current project estimate with similar past projects and consults senior engineers to validate the feasibility.
7. Define risk management in software projects and explain its importance during project planning.
Answer:
Risk management identifies, analyzes, and plans responses to potential problems that could affect a project. It helps minimize negative impacts and prepares contingency plans.
Example:
In planning the development of autonomous vehicle software, risk management identifies hardware failures and regulatory changes as risks, allowing the team to develop mitigation strategies early.
8. List and explain at least three types of risks commonly encountered in software projects.
Answer:
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Technical Risk: New or unproven technology might fail (e.g., integrating a new AI module).
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Schedule Risk: Project might take longer than planned due to unforeseen complexity.
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Resource Risk: Lack of skilled personnel or budget overruns.
Example:
A project introducing blockchain payment could face technical risks due to unfamiliar technology, schedule risks from delays, and resource risks if specialized developers aren’t available.
9. How can risk management strategies be integrated into the software project planning phase?
Answer:
By identifying risks early, assessing their impact, prioritizing them, and planning mitigation strategies, including contingency plans and risk monitoring throughout the project lifecycle.
Example:
In planning a healthcare app, the team schedules regular risk reviews and assigns a risk manager to monitor security vulnerabilities and compliance risks.
10. What role does historical project data play in improving the accuracy of software project cost and effort estimates?
Answer:
Historical data from previous projects helps calibrate estimation models, provides benchmarks, and reduces guesswork by reflecting real past outcomes.
Example:
A software company uses data from past mobile app projects to estimate development time for a new app, adjusting for size and complexity, resulting in more reliable schedules and budgets.
Unit-2 Part 2
1. What is cohesion in software design, and why is high cohesion desirable?
Answer:
Cohesion refers to how closely related the functions within a single module or component are. High cohesion means a module performs a single, well-defined task, which improves maintainability and understandability.
Example:
In a banking system, a module dedicated solely to processing transactions (e.g., deposit, withdrawal) exhibits high cohesion compared to a module handling both transactions and user authentication.
2. Explain coupling and the difference between tight and loose coupling.
Answer:
Coupling is the degree of interdependence between software modules. Tight coupling means modules heavily depend on each other, making changes difficult. Loose coupling means modules interact through well-defined interfaces, promoting flexibility.
Example:
A tightly coupled online shopping cart module directly accessing the payment processing module’s internal data makes updates risky; loosely coupled modules communicate via APIs, allowing independent updates.
3. List and briefly describe the common types of cohesion.
Answer:
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Functional Cohesion: Elements work together to perform a single function.
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Sequential Cohesion: Output from one part is input to another.
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Communicational Cohesion: Elements operate on the same data.
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Procedural Cohesion: Elements execute in a specific order but unrelated tasks.
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Temporal Cohesion: Elements executed together in a time frame (e.g., initialization).
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Logical Cohesion: Elements grouped logically but perform different tasks.
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Coincidental Cohesion: Elements with no meaningful relationship (undesirable).
Example:
A module performing all file I/O operations (functional cohesion) is better than one that both handles file I/O and user input (logical cohesion).
4. What are the main types of coupling, and which type is considered the best?
Answer:
Common types of coupling include:
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Content coupling (worst): One module modifies internal data of another.
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Common coupling: Modules share global data.
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Control coupling: One module controls the flow of another.
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Stamp coupling: Modules share a composite data structure but use only parts.
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Data coupling (best): Modules share data through parameters.
Example:
In a payroll system, passing only an employee’s salary (data coupling) is preferred over sharing the entire employee record (stamp coupling).
5. Describe the function-oriented design approach.
Answer:
Function-oriented design focuses on decomposing a system into functions or processes that transform inputs to outputs. It emphasizes top-down decomposition and data flow.
Example:
In a hotel reservation system, functions like "Check Availability," "Book Room," and "Cancel Reservation" are designed as separate processes.
6. What distinguishes Object-Oriented Design (OOD) from Function-Oriented Design?
Answer:
OOD organizes software around objects that combine data and behavior (methods), emphasizing encapsulation, inheritance, and polymorphism. Function-oriented design separates data and functions.
Example:
In a car rental system, OOD would model a Car object with attributes (model, license) and methods (rent, return), whereas function-oriented design would have separate functions and data structures.
7. Explain the concept of encapsulation in Object-Oriented Design.
Answer:
Encapsulation bundles data and methods into a single unit (class) and restricts direct access to some components, protecting the internal state and promoting modularity.
Example:
In a banking app, the Account class hides the balance variable and provides methods like deposit() and withdraw() to control access.
8. What are key considerations in User Interface (UI) Design?
Answer:
UI design focuses on usability, accessibility, consistency, feedback, and simplicity to ensure users can interact effectively with the software.
Example:
An e-commerce website uses clear navigation menus, consistent colors, and responsive design to help users easily browse and buy products.
9. How does modular design contribute to software maintainability?
Answer:
Modular design breaks a system into independent, interchangeable modules with high cohesion and low coupling, making it easier to update or fix parts without affecting others.
Example:
In a content management system, separating the user authentication module from the content editor allows independent updates and reduces bugs.
10. Give an example of how coupling affects software flexibility during maintenance.
Answer:
If a reporting module in a sales system is tightly coupled with the sales processing module, changing reporting formats might require modifying the sales processing code, increasing maintenance effort. Loose coupling allows changing reports without affecting sales logic.
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