"Object-oriented Analysis (OOA) is a method of analysis that examines requirements from the perspective of the classes and objects found in the vocabulary of the problem domain" - Grady Booch


Object-oriented Analysis

  • Analysis Model provides the foundation for the Design Model
  • Focus on Hi-level Business Objects
  • Concentrate on activities of the User of the business process
  • Avoid detailed design tasks

Requirements Analysis

  • Who are the Users and the Customers? 
  • Why do they want this system? 
  • Define what the business needs to accomplish
  • Define Constraints on how a solution is manifested but not on how system it is designed
  • What is accomplished conceptually
  • What is required to interface to the system
  • What is required to operate it


Enterprise-wide Vs Project-Specific 

  • Enterprise-wide requirements provide Re-Use
  • Requirements common to a project can be obtained by referring to enterprise-wide requirements 
  • Project-specific requirements should be evaluated for re-factoring into enterprise-wide requirements

Requirements 

  • Functional Requirement
  • Non-Functional Requirement
    • Interface Constraint
    • Operational Constraint


The Big Process Picture 

  • Requirements Analysis process fits into other processes within Integrated Requirements
  • Deliverables output from one process become inputs to other processes
  • Integrated Requirements provide the glue between the business side and the technology side

Essential Elements for Requirements Analysis 

  • Clarity
  • Efficiency
  • Priority
  • Quality
  • Traceability
  • Completeness
  • Accuracy


Guidelines for Requirements Analysis

  • Problem Vs Solution Evolution 
  • Abstraction
  • Iteration 
  • Modeling
  • Re-Use

UML 

  • Unified Modeling Language
  • Successor to methods of Booch, Rumbaugh & Jacobson
  • A modeling language and not a method

The Unified Modeling Language (UML) is the industry-standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems. It simplifies the complex process of software design, making a "blueprint" for construction. The UML definition was led by Rational Software's industry-leading methodologists: Grady Booch, Ivar Jacobson, and Jim Rumbaugh.


Use Cases

  • A typical interaction a user has with a system to achieve a goal
  • An essential tool in Requirements Capturing
  • Provides User-visible function
  • Use Cases are part of UML


Some Definitions

  • Rectangles Indicate a computer system boundary (Human are always outside "systems")
  • Ovals Indicate a "use case" and straddle the boundary when a human Actor is involved, or can be inside a system when non-humans are interacting
  • Actors An actor is a role that an external object or user plays vis the System
  • Arrows Indicate activity or flow of information

Business Transaction Scenarios

  • Business Transaction Scenarios describe all the possible interactions between the system and the external objects of the outside world. BTS are modeled as Use Cases
  • Normal Scenario captures the normal interaction between the actor and the system
  • Abnormal Scenario captures interaction that occurs during exceptions or error conditions

Sequence Diagrams 

A Sequence Diagram provides a diagrammatic representation of a specific instance of a Use Case (a scenario)


Format of Use Cases [Optional Information]

Scenarios and Use Cases will have the following sections in this order: 

  • Purpose
  • Assumptions
  • Actors
  • Use Cases Used
  • Use Cases Extended
  • Preconditions 
  • Postconditions
  • Basic Course 
  • Alternate Course
  • Rules
  • Interface Contraints 
  • Operational Constraints



Business Transaction Scenario: Learning Administration System

1. Scenario: Learning Administration System

The Learning Administration System (LAS) depicts the scenario where a student enrolls for a Program or Courses at a Learning Institution, attends the courses scheduled and after completion of the same, applies for various job positions at different companies.

Who are the Actors? 
  • Admissions Rep
  • Instructor
  • Admissions Director
  • Financial Aid Director
  • Education Director
  • Career Services Director
  • Accountant
Let us model the system



Source: Massachusetts Institute of Technology, https://ocw.mit.edu/courses/4-297-special-problems-in-architecture-studies-fall-2000/resources/uml1/
Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 License.

Last modified: Friday, 8 December 2023, 1:04 PM