TOPIC 2

Software Design: Software Architecture (Part 1)

Learning Outcomes

  • Define software architecture

  • Differentiate architecture vs design

  • Explain why architecture is important

  • Identify common architectural patterns

  • Apply architecture concepts to a real system

What is Software Architecture?

  • Definition: Software architecture is the high-level structure of a system, which includes:

    • Components: The individual parts or modules of the system.

    • Relationships: How these components interact or relate to each other.

    • Interactions: The ways in which components communicate and collaborate.

  • Analogy: "Architecture is the blueprint of a system before we build it."

Importance of Architecture

  • Consequences of Lack of Architecture:

    • A system can become disorganized and messy.

    • Difficulty in scaling or maintaining the system effectively.

Key Elements of Architecture

  1. Components

    • Definition: The building blocks of a system; analogous to rooms in a house or departments in an organization.

    • Example (Mobile Banking App):

      • Login module

      • Fund transfer module

      • Account history module

      • Notification module

  2. Connectors

    • Definition: The means through which components communicate; can be likened to doors or hallways in a house.

    • Example (Mobile Banking App):

      • The login screen interacts with the authentication service.

      • The transfer module communicates with the database.

      • Notifications are sent via a messaging service.

  3. Constraints

    • Definition: Rules that the system must follow, similar to building codes or laws for a company.

    • Example (Mobile Banking App):

      • Compliance with banking security regulations.

      • Password requirements (e.g., must be at least 8 characters).

      • All transactions must be logged.

  4. Quality

    • Definition: The 'soft' goals defining the system's performance and efficiency, equated to comfort and safety in a house.

    • Example (Mobile Banking App):

      • Performance must be swift (e.g., login < 2 seconds).

      • Security measures: User data must be encrypted.

      • Scalability: The app must handle 100,000 users.

      • Reliability: The app should not crash during transfers.

Architecture vs Design

  • Architecture

    • Focus: High-level structure of the system.

    • Phase: Early in the development process.

    • Scope: Big picture view, understanding overall system flow.

  • Design

    • Focus: Low-level implementation details of the system.

    • Phase: Later in the development process.

    • Scope: Small details, such as database schema and user interface layout.

Why Software Architecture is Important?

  • Enhances system scalability.

  • Improves maintainability of the system over time.

  • Supports performance optimization strategies.

  • Enables team collaboration across different areas of development.

  • Reduces development risks by anticipating potential problems.

  • Quote: "Bad architecture = expensive problems later."

Architectural Patterns

  1. Layered Architecture

    • Analogy: Similar to building a layered cake or a company organized by departments.

    • Structure:

      • Presentation Layer: User-facing part (e.g., cashier in a store).

      • Business Logic Layer: Processing rules and functionalities (e.g., manager processing sales).

      • Data Layer: Information storage and retrieval (e.g., warehouse for products).

    • Flow: User → UI → Logic → Database

    • Example (Mobile Banking App):

      • Presentation Layer: Mobile app screens (login, transfer, account summary).

      • Business Logic Layer: Processes requests (validates logins, checks balances).

      • Data Layer: Holds account and transaction records, user data.

  2. Client-Server Architecture

    • Definition: A distributed system structure with a client requesting services and a server providing them.

    • Example (Mobile Banking App):

      • Client: Mobile banking app on user's phone, sending requests (e.g., "Show my balance.").

      • Server: Bank's backend server processing requests, accessing databases, sending responses.

  3. Model-View-Controller (MVC)

    • Definition: An architectural pattern for separating data, user interface, and logic.

      • Model: Manages data and business rules.

      • View: Represents the UI elements.

      • Controller: Processes user input, updates the model and the view based on actions.

    • Example (Mobile Banking App):

      • Model: Contains account balances, transaction history, user profiles.

      • View: UI elements like login screens and account summaries.

      • Controller: Manages actions (e.g., "Transfer $100," "Update profile").

Architectural Patterns Comparison

Pattern

Best For

Strengths

Weaknesses

Example

Layered

Structured Systems

Easy to maintain, separates concerns

Can incur overhead and be slower

Enterprise Payroll System

Client-Server

Distributed systems

Centralized control, multiple clients

Server bottlenecks, network dependency

Online Multiplayer Game

MVC

UI-heavy apps

Clear separation, easy UI updates

Slightly complex to implement

E-commerce Web Application

Summary

  • Architecture: Represents the high-level blueprint of a system.

  • Focuses on components, layers, interactions, and architectural patterns.

  • Considered critical for the success of a system.

  • Architectural patterns provide structured approaches to building systems effectively.

Thank You

Here are 20 multiple-choice questions (MCQs) based on software architecture:

  1. What is the primary focus of software architecture?
    a) Coding standards
    b) High-level structure of the system
    c) User interface design
    d) Individual components
    Answer: b)

  2. What does a component in software architecture refer to?
    a) The overall system
    b) Interaction protocols
    c) Individual parts or modules
    d) User documentation
    Answer: c)

  3. Why is architecture important in software development?
    a) It makes coding easier
    b) It enhances system scalability and maintainability
    c) It eliminates bugs
    d) It focuses solely on design
    Answer: b)

  4. Which of the following is NOT a consequence of lack of architecture?
    a) Disorganized system structure
    b) Improved performance
    c) Difficulties in scaling
    d) Maintenance challenges
    Answer: b)

  5. In a modular software architecture, components are compared to:
    a) Rooms in a house
    b) Employees in a company
    c) Cars in a parking lot
    d) Websites on the internet
    Answer: a)

  6. What do connectors do in software architecture?
    a) Store data
    b) Manage user input
    c) Facilitate communication between components
    d) Define coding standards
    Answer: c)

  7. Which layer of the layered architecture deals with data storage?
    a) Presentation Layer
    b) Data Layer
    c) Business Logic Layer
    d) Connectors
    Answer: b)

  8. A client-server architecture is defined by:
    a) All components being on the same server
    b) A distributed system where clients request services and servers provide them
    c) No communication between components
    d) Single-user interaction only
    Answer: b)

  9. In the MVC pattern, which component manages data and business rules?
    a) Model
    b) View
    c) Controller
    d) Connector
    Answer: a)

  10. What defines quality in architecture?
    a) Coding techniques
    b) Performance and efficiency goals
    c) Number of components
    d) Design aesthetics
    Answer: b)

  11. What phase does architectural design typically occur in?
    a) After detailed design
    b) Early in the development process
    c) During the testing phase
    d) After user feedback
    Answer: b)

  12. How does software architecture impact team collaboration?
    a) It reduces overall team size
    b) It creates confusion among developers
    c) It facilitates communication across different development areas
    d) It is irrelevant to team dynamics
    Answer: c)

  13. Which is a common quote related to software architecture?
    a) “Good architecture leads to slow performance.”
    b) “Bad architecture = expensive problems later.”
    c) “Architecture is just fluff.”
    d) “Design is key; architecture does not matter.”
    Answer: b)

  14. What is an example of a constraint in a banking application?
    a) User interface design principles
    b) Compliance with security regulations
    c) Marketing strategies
    d) Coding languages used
    Answer: b)

  15. Which architectural pattern separates the user interface, data, and business logic?
    a) Layered architecture
    b) Client-server architecture
    c) Model-View-Controller (MVC)
    d) Component-based architecture
    Answer: c)

  16. What is the role of the presentation layer?
    a) Data processing
    b) User interaction
    c) Server configuration
    d) Database management
    Answer: b)

  17. In a software architecture context, what do interactions refer to?
    a) Connections between servers
    b) User communication with the system
    c) How components communicate and collaborate
    d) Transactions processed by the database
    Answer: c)

  18. What does the architecture vs design distinction emphasize?
    a) Only coding styles
    b) High-level vs low-level concerns
    c) Marketing strategies
    d) User interface improvements
    Answer: b)

  19. Which of the following is a characteristic of layered architecture?
    a) Components are tightly coupled
    b) It allows separation of concerns
    c) All layers must be changed simultaneously
    d) There are no defined layers
    Answer: b)

  20. Why should developers consider software architecture early in the process?
    a) To avoid rework and reduce risks later in development
    b) It has no impact on the final product
    c) To create more components than necessary
    d) To limit team collaboration
    Answer: a)