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optional · CSS study notes

Analysis Modeling (2016)

CSS CS Optional — Paper-I, Section-B, Topic V. Translates requirements into structured models before design begins.

🔑 The 4 Models

  • DFD (Data Flow Diagram): data movement, level by level, from a single context diagram down.
  • Use-Case Diagram: functional requirements from user's view.
    • Actors = users/external systems
    • Use Cases = goals actor can achieve
    • <<include>> = always incorporates another use case
    • <<extend>> = optionally extends another
  • Class Diagram: structural — classes, attributes, relationships (NOT behavior).
  • State Diagram: event-driven behavior — states + transitions. Best for reactive/embedded systems.

🔥 Past Papers

  • 2026 Q6(b) — purpose of Use Case Diagrams.

⚠️ MCQ Trap

  • Use Case Diagram = behavior (what system does)
  • Class Diagram = structure (what system is made of)
  • Don't swap these when comparing.

📜 Past-Paper Questions & MCQs (CSS 2016–2026)

2016 · Paper-I · Q8(a) · 5 marks

Q. What are the purposes of Data Flow Diagrams and Entity-Relationship diagrams? Give an example diagram of each.

Ans.

  • DFD purpose: to show how data moves through a system: external entities, processes, data stores and data flows. It models processing and is used in analysis.
[Student] --application--> (Register course) --record--> [[Student DB]]
                                    |--confirmation--> [Student]
  • ERD purpose: to model the data structure: entities, their attributes and the relationships between them. It is the basis of database design.
erDiagram
    STUDENT ||--o{ ENROLLMENT : makes
    COURSE  ||--o{ ENROLLMENT : has
    STUDENT {
        int RegNo PK
        string Name
    }
    COURSE {
        string Code PK
        string Title
    }

2021 · Paper-I · Q7(a) · 8 marks (UML)

Q. Write a detailed note on the Unified Modeling Language.

Ans.

  • UML is a standard graphical language for specifying, visualising and documenting software systems (maintained by OMG).
  • Structure diagrams: class, object, component, deployment, package diagrams.
  • Behaviour diagrams: use case, activity, state machine, sequence and communication diagrams.
  • Benefits: a common language for developers and customers, better design review, and generation of code skeletons.

2026 · Paper-I · Q6(b) · 6 marks

Q. What is the purpose of Use Case Diagrams?

Ans.

  • A use case diagram shows what a system does from the user's point of view: its actors (users or external systems), the use cases (goals or functions) and the relationships between them.
  • Purposes: capture functional requirements, communicate scope between users and developers, identify actors and goals, and serve as the basis for test cases and later design.
  • Notation: actors as stick figures, use cases as ovals, a system boundary box, and relationships (association, include, extend, generalisation).
Student ── (Register for course)
Student ── (View result)
Teacher ── (Enter marks) ──include──> (Login)