Analysis & Design Using UML

Foundations

Object-Oriented Analysis and Design (OOAD)

A method for understanding a problem (analysis) and shaping a solution (design) as collaborating objects, using UML to model both.

Analysis vs. Design

Analysis clarifies what the system must do in the problem domain; design decides how it will be built in the solution domain.

UML

The Unified Modeling Language, the standard visual notation for modeling object-oriented structure and behavior.

Iterative OOAD

Analysis and design evolve iteratively as understanding grows, rather than being completed in one pass.

Analysis

Analysis Model

A model of the problem domain capturing key classes, responsibilities, and relationships, independent of technology.

Use Case Realization

Showing how analysis objects collaborate to fulfill a use case, connecting requirements to structure.

Boundary, Control, Entity

Analysis stereotypes: boundary (interfaces), control (coordination), and entity (domain data) objects.

Responsibilities

What each class knows and does; assigning them well drives cohesive, maintainable models.

Design

Design Model

A refinement of the analysis model that adds implementation decisions — technology, interfaces, and structure — to enable building the system.

Architecture

The high-level structure of components and their relationships that provides a robust framework for detailed design.

Layering

Organizing the system into layers (e.g., presentation, domain, data) to separate concerns and manage dependencies.

Design Principles

Encapsulation

Hiding internal data and exposing behavior through interfaces, reducing coupling and protecting invariants.

Cohesion and Coupling

Good design maximizes cohesion within a class and minimizes coupling between classes for maintainability.

SOLID Principles

Five OO design guidelines — Single Responsibility, Open-Closed, Liskov Substitution, Interface Segregation, Dependency Inversion — for robust design.

Design Patterns

Proven, reusable solutions to recurring design problems (e.g., Strategy, Observer, Factory).

Structure Diagrams

Class Diagram

Shows classes, attributes, operations, and relationships — central to both analysis and design models.

Package Diagram

Organizes model elements into packages to manage large models and dependencies.

Component Diagram

Shows software components, their interfaces, and dependencies for design-level structure.

Deployment Diagram

Shows how software artifacts are deployed onto hardware nodes in the runtime environment.

Behavior Diagrams

Sequence Diagram

Shows objects collaborating over time via messages to realize behavior and design interactions.

Activity Diagram

Models workflow and logic as actions, decisions, and flows, useful for processes and complex behavior.

State Machine Diagram

Models the states and transitions of objects with significant lifecycle behavior.

Quality

Traceability

Linking requirements to analysis to design to tests so coverage and change impact stay clear.

Just Enough Modeling

Creating the models that add value for understanding, communication, and design, without over-documenting.