Intro to Object Oriented Design and Analysis

Design and Analysis falls under the larger blanket of software engineering, which encompasses many activities.

• Primary software development activities
  • Problem definition
  • Analysis
  • Design (overall system design, object/module design)
  • Implementation
  • Testing
• Some other software engineering activities/issues
  • Installation
  • Maintenance
  • Quality Assurance (encompasses more than just testing during development)
  • Communication
  • Management

Modeling

• A model is an abstraction describing a system or a subset of a system
  • Helps deal with complexity
• A view depicts selected aspects of a model.
  • Each view focuses on a subset of the model
  • Example: All the blueprints for a house constitute a model, but one view might focus just on the plumbing schematics
• A notation is a set of graphical or textual rules for representing views of models
  • UML (Unified Modeling Language) contains notations for various types of models in object-oriented development

Application vs Solution Domain

• Application Domain -- all aspects of the user's problem
  • The environment that the system is to operate in
  • Can change over time (includes physical environment, people, work processes, etc).
  • Modeling and analysis needed to understand things from the user's point of view
  • Modeling it involves problem specification (or requirements elicitation) and analysis
• Solution Domain -- modeling space of all possible solutions (systems)
  • Usually modeled in much more detail than application domain
  • Need to be able to translate solution model into code
  • Involves overall system design, as well as object/module design
  • Developer's point of view

Primary Parts of a System's Model

• Functional model
  • Describes the functionality of a system from the user's point of view
• Object Model
  • Describes the structure of a system (and of subsystems) in terms of objects, attributes, operations, and associations
• Dynamic Model
  • describes the internal behavior of the system

UML -- Unified Modeling Language

• Intended to provide standard notations for use with object-oriented modeling
• Attempts to integrate the best elements of previous leading notations
• Supported now by a number of CASE (Computer-Aided Software Engineering) tools
• We will use UML in this course to learn about and practice with design and analysis activities

UML Diagram Types

• Use Case Diagram
  • Describes the functionality from the user's perspective. Used for the functional model of a system
• Class/Object Diagram
  • Describes the structure of a system or subsystem. Used in the object model of a system
• Sequence Diagram
  • A form of interaction diagram. Describes behavior as a sequence of messages exchanged among a set of objects. Used in the dynamic model of a system
• State Machine (or Statechart) Diagram
  • Describes behavior in terms of the possible states of a single object. Used in the dynamic model of a system

• Activity Diagram - help represent control flow and data flow through a system
• Package Diagram - used for grouping related classes and objects together
• Deployment Diagram - represents relationship between software run-time components and the hardware nodes of a system

A few sample diagrams can be found on this Powerpoint slide show