Before

Feasibility study

Purpose

  • Not for problem solving
  • Should be cheap and quick

Mission

  • contribution?
  • implentment? schedule and budget
  • integration?

Techinical Economic Operational

Analysis Model

Data Flow Diagram(DFD)

describe how data flows among different system modules

  • Transformational processes
    • Process
    • Terminator
  • Collections of data
    • Data Store
  • Flows of data
    • Data flow

Hierarchy

  • Level
  • Detail

Useful in Validation

Summary

  • Effective for transaction-intensive systems
  • Lack of explicit data relationships
  • Cannot demostrate temporal features
  • Not appropriate for control systems

For industry

  • Completeness

  • Consistency

  • Precision

Specification

  • Functional Requirement
  • Non-functional Requirement
    • Usability
    • Flexibility
    • Reliability
  • Vision and Scope Document
    • Business Requirements
  • Use-Case Document
    • User Requirements
    • Business Rules
    • Quality Attributes
      • Business Rules
  • Software Requirements Specification
    • Functional Requirements
      • Business Rules
      • Quality Attributes
        • Business Rules
      • Use-Case Document
    • Ecternal Interfaces
    • Constraints

Software Requirement Specification(SRS)

Attributes

  • Well-structured
  • Abstract
  • Complete
  • Easy to understand
  • Unambiguous
  • Verifiable
  • Self-Consistent