Software Design and Architecture Week 1 & 2

Software Engineering Overview

• Software consists of instructions that facilitate user interaction with computer hardware to perform tasks.
• Engineering involves generating and evaluating designs to meet client objectives within specified constraints.
• Software engineering is systematically applied to software development, operation, and maintenance according to IEEE definitions.

Software Engineering Phases

• Phases include Requirements, Design, Implementation, Testing, and Maintenance.
• Requirements analysis leads to the software design including architecture and detailed models.
• Implementation uses programming languages while ensuring software meets its specifications.

Importance of Software Design

• Facilitates organization and systematic problem-solving which is critical to meeting product specifications.
• Effective design helps address complexity in projects and improves human resource allocation.
• Good design provides structured models that represent software systems and support evaluation of quality attributes.

Problem-Solving in Software Design

• Problem-solving occurs in three states: Initial (formulating problems), Operational (thinking of viable solutions), and Goal (identifying and validating solutions).
• Functional fixedness may limit creative problem-solving; designers must consider multiple perspectives and unconventional solutions.

Holistic Problem-Solving Framework

• The framework includes interpreting problems, evaluating constraints, collaborative brainstorming, synthesizing possibilities, evaluating solutions, and implementing resolutions.
• This approach aids engineers in navigating the complexities encountered throughout the development process.

Software Engineering Design Definition

• Design entails identifying and evaluating architectural details, ensuring the software meets functional and non-functional requirements.
• It encompasses both the process (activities and tasks) and the product (artifacts resulting from the process).

Challenges in Software Design

• Complexity of software systems complicates quality development, leading to five primary challenges:

  • Requirement Volatility: Changes during the lifecycle lead to costly adjustments, especially in later stages.

  • Inconsistent Development Processes: Poorly established or understood processes hinder bridging requirements with construction.

  • Rapid Technology Changes: New technologies demand quick adaptation, impacting project timelines and integration with existing systems.

  • Managing Design Influences: Conflicting stakeholder demands necessitate design trade-offs, challenging large system development.

  • Ethical Considerations: Design decisions must consider environmental impact and user effects, requiring strong professional ethics and leadership.

Summary of Design Importance

• Studying software design is critical for ensuring effective development, managing changing requirements, facilitating efficient resource use, and improving overall project management.

Software Design Process Overview

• Involves activities that coordinate resources for software production, producing design models like use cases and UML diagrams.

Major and Supportive Activities

• Major Activities: Software architecture, detailed design, construction design, human-computer interface design.
• Supporting Activities: Documentation and management activities essential for organizational coherence.

Software Architecture

• Represents macro-design through models showcasing quality and functionality.
• Utilizes black-box models for quality evaluation and stakeholder alignment.
• Focuses on system structure and quality aspects before moving into detailed design.

Detailed Design

• Concerned with the internals of components and interfaces after architecture is sufficiently complete.
• Transforms architectural outlines into a structured, behavior-focused design.
• Key tasks include:
  • Component Design: Defines internal structures, using UML for class and sequence diagrams.
  • Interface Design: Specifies interaction protocols between components, both internal and external.

Construction Design and Human-Computer Interface

• The most granular level of design, focusing on user interface optimization and algorithmic implementation analysis.

Distribution of Design Activities

• Design tasks occur throughout the software development life-cycle, not just within a defined phase.

Role of Software Designers

• Systems Engineer: Oversees the entire development process, including hardware-software interaction.
• Software Architect: Designs systems with a focus on external properties and quality.
• Component Designer: Works on the internal design of software components, requiring strong coding skills.
• User Interface Designer: Enhances usability and user experience.

Software Design Fundamentals

• Key Design Principles:
  • Modularization: Decomposes systems into manageable modules for ease of development and maintenance.
  • Abstraction: Emphasizes essential characteristics while deferring unnecessary details for clarity.
  • Encapsulation: Controls access to data and services, hiding implementation specifics.
  • Cohesion: Measures how closely related tasks within a module are; high cohesion is desirable.
  • Coupling: Describes the interdependence between modules; lower coupling is preferable to enhance reusability.
  • Separation of Interface and Implementation: Facilitates different implementations while abstracting interface details.
  • Completeness: Ensures all required functions are provided by design units.
  • Sufficiency: Guarantees that units only provide necessary services.

Design Strategies

• Object-Oriented Design: Focuses on object identities, states, behaviors, and supports inheritance and polymorphism.
• Structured Design: Employs a top-down approach, focusing on decomposing functions into independent modules.

Design Considerations

• Minimize complexity and ensure the system can adapt to future changes, integrating design techniques to allow for extensibility.

Summary

• Software design integrates engineering principles, problem-solving strategies, and a deep understanding of software challenges like requirements volatility and technology adaptation.
• The process covers phases of design from initiation to the architectural frameworks needed to guide development phases effectively.

Software Design Process

• Involves systematic planning, creating, and maintaining software through various stages.
• Key stages include architecture design, detailed design, construction design, and user interaction.

Architecture Design

• Defines the high-level structure of the software system.
• Addresses components, their interactions, and aligns with user and business requirements.

Detailed Design

• Focuses on how each component will implement functionality.
• Creates specifications for programming, including data structures and algorithms.

Construction Design

• Involves actual coding and building of the software based on designs.
• Emphasizes implementation details and adheres to design specifications.

Computer-Human Interaction Design

• Enhances usability by focusing on the user experience.
• Ensures efficient communication between the user and the software, often utilizing principles of visual design.

Design Documentation

• Essential for communicating design intentions and decisions.
• Serves as a reference guide for developers, testers, and stakeholders throughout the software lifecycle.

Management Activities

• Organize and oversee the entire design process to ensure quality and standards.
• Involve strategies for risk management, resource allocation, and stakeholder engagement.

Object-Oriented Strategy

• Emphasizes reuse and modularity by organizing software around objects rather than actions.
• Encourages the use of inheritance and polymorphism to enhance design flexibility.

Functional (Structured) Strategy

• Focuses on functions and their interactions, often using a top-down approach.
• Prioritizes a linear process where modules are developed in sequence.

Design Considerations

• Minimize Complexity: Aim for simplicity to facilitate understanding and maintenance.
• Design for Change: Anticipate future modifications and design flexibly.
• Modularization: Break systems into independent, interchangeable modules.
• Abstraction: Use simplified models to reduce complexity in design.
• Encapsulation: Hide internal workings of modules from outside interference.
• Coupling: Minimize interdependencies between modules for easier maintenance.
• Cohesion: Keep related functions within the same module to enhance its functionality.
• Separate Interface from Implementation: Distinguish how components communicate from how they operate.
• Completeness: Ensure the design covers all required functionalities.
• Sufficiency: Design must provide enough detail and resources for development.

Design Strategies

• Involve methods and techniques that guide decisions throughout the design process.
• Can include iterative development, prototyping, and agile methodologies to enhance responsiveness to changing requirements.

This quiz covers the fundamentals of software design and architecture explored in the first two weeks of the course. It delves into essential topics such as software engineering, problem-solving techniques, and the software design process. Understanding these concepts is crucial for anyone studying or working in the field of software development.