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Loan Application State Diagram

Run the State Diagram MicroSim Fullscreen

About This MicroSim

A loan application is a textbook example of an object with a meaningful lifecycle. It moves through a fixed set of states — Draft, Submitted, Under Review, Conditionally Approved, Awaiting Documents, Approved, Denied, Funded, Closed, Withdrawn — and only a small subset of transitions is legal between them. Toggling Show Invalid Transitions makes the state diagram's role as a business-rule guardrail visible.

How to Use

  1. Click Play Example Application to walk one application from Draft to Closed
  2. Click any state for the business operations legal in that state
  3. Toggle Invalid Transitions to see the forbidden moves the state machine prevents

Embedding This MicroSim

<iframe src="https://dmccreary.github.io/information-systems/sims/loan-application-state-diagram/main.html"
        height="722px" width="100%" scrolling="no"></iframe>

Lesson Plan

Learning Objectives

By the end of this activity, students will be able to:

  1. Read a UML state diagram and identify states, transitions, and events
  2. List legal transitions out of any state
  3. Explain why a state diagram is the right tool for an object with a lifecycle
  4. Recognize how a state machine acts as a business-rule guardrail

Suggested Activities

  1. State Walk (5 min) — Click each state; recite legal operations
  2. Forbidden Move (10 min) — Toggle invalid transitions; explain why each one is forbidden
  3. Add a State (15 min) — Propose adding "Auto-Underwritten." Where would it fit, and what transitions would change?

References

  • OMG. UML 2.5 Specification, State Machines.
  • Harel, D. (1987). Statecharts: A Visual Formalism.