With detailed, stakeholder-validated use case specifications now in place (Module 4), the project transitions from what the system should do (requirements) to how the system will actually behave and be organized (design). This is the pivotal moment where textual narratives become executable models: visual workflows, interaction sequences, class structures, and data schemas that developers can implement and testers can verify.
Module 5 focuses on four complementary modeling perspectives that together form a coherent design blueprint:
- Behavior Modeling — Activity Diagrams that show the step-by-step workflow of a use case or business process, including decisions, parallelism, and loops.
- Interaction Modeling — Sequence Diagrams that illustrate the dynamic exchange of messages between actors, the system, and its internal components over time.
- Static Structure — Class Diagrams that define the core objects, attributes, operations, and relationships that realize the system’s logic.
- Data Modeling — Entity-Relationship Diagrams (ERDs) that outline persistent data entities, their attributes, and relationships — ensuring the database schema stays aligned with functional requirements.
Visual Paradigm’s AI-Powered Use Case Modeling Studio dramatically accelerates this traditionally labor-intensive phase by generating initial versions of these diagrams directly from:
- The detailed use case flows (main, alternative, exception)
- Pre- and postconditions
- Identified «include» / «extend» relationships
- Actor and system boundary information
The AI applies domain-aware heuristics and UML best practices to propose meaningful partitions, lifelines, messages, classes, multiplicities, and entities. You then refine these drafts in the same integrated environment — adding guards, notes, stereotypes, or MVC layering — while maintaining full traceability back to the originating use case.
Why These Four Views Matter Together
- Activity Diagrams clarify complex logic and decision paths (great for developers and testers).
- Sequence Diagrams reveal the order of operations and responsibilities between components (critical for API design and integration).
- Class Diagrams provide the architectural foundation — the “nouns” and “verbs” of the implementation.
- ERDs ensure data consistency and prevent mismatches between behavior and persistence.
Together they form a traceable, multi-view design that reduces implementation surprises and supports code generation, reverse engineering, or test automation in later stages.
Practical Examples
Example 1: GourmetReserve – Mobile Dining Reservation App
- Activity Diagram (Book a Table) AI-generated from the detailed flow:
- Start → Search tables → [Decision: Tables available?] → Yes → Select slot → Process Payment → Confirm → End → No → [Fork] Offer alternatives OR Join waitlist → End
- Parallel swimlanes: Diner vs. System vs. Payment Gateway
- Refinement you add: Guard condition “[party size ≤ 10]” on one path; exception handling loop for failed payment retries (max 3 attempts).
- Sequence Diagram (Book a Table – happy path) Lifelines: Diner : MobileApp : ReservationService : PaymentGateway Messages: searchTables() → showResults() → selectSlot() → reserveAndPay(deposit) → redirectToPayment() → paymentApproved() → confirmReservation() → sendNotification()
- Class Diagram (core entities) Classes: Reservation, Table, Restaurant, Diner (with attributes like bookingTime, status, depositAmount), associations (Reservation 1..* → Table, Diner 1 → * Reservation), operations (e.g., Reservation.confirm(), Table.isAvailable()).
- ERD Entities: Restaurant, Table, Reservation, Payment, Customer Relationships: Reservation references Table (1:1 at time of booking), Reservation has Payment (1:1), Customer places Reservation (1:*).
Example 2: SecureATM – Withdraw Cash
- Activity Diagram Swimlanes: Customer – ATM Interface – Core Banking System Flow: Insert card → [PIN valid?] → Select withdraw → Enter amount → [Funds + limit OK?] → Dispense cash → Update balance → Print receipt (optional parallel flow)
- Sequence Diagram Actors: Customer : ATM : AuthService : AccountService : CashDispenser Key messages: authenticate(pin) → validateWithdrawalLimit(amount) → debitAccount(amount) → dispense(amount)
- Class Diagram Core: Account, Transaction, ATM, Card Inheritance: WithdrawalTransaction extends Transaction Composition: ATM has CashDispenser and CardReader
- ERD Entities: Account, TransactionLog, ATMDevice, Card Relationships: TransactionLog records withdrawal from Account, ATMDevice tracks lastReplenishmentDate
Example 3: CorpLearn – Take Final Assessment
- Activity Diagram Decision nodes: Time remaining? → Submit answers → [Score ≥ 80%?] → Issue certificate OR Offer retake Parallel path: Record progress after each section
- Sequence Diagram Learner : WebApp : AssessmentService : ScoringEngine : CertificateService Messages: startAssessment() → submitAnswers() → calculateScore() → if passing → generateCertificate()
- Class Diagram Classes: Course, Assessment, Question, LearnerProgress, Certificate Associations: Assessment has Questions (1:*), LearnerProgress tracks status per Course
- ERD Entities: Learner, Course, AssessmentAttempt, Certificate Relationships: AssessmentAttempt belongs to Learner and Course, Certificate issued from successful Attempt
Key Takeaways for This Module
By the end of Module 5, you will have:
- Executable visual models that bring use case specifications to life
- Consistent alignment across dynamic behavior (Activity/Sequence) and static structure (Class/ERD)
- AI-generated drafts that save hours of manual drawing while following UML standards
- A design package that is traceable to requirements and ready for implementation planning, code skeleton generation, or detailed test design
The AI handles the mechanical translation from text to diagrams — you focus on validating correctness, adding architectural decisions (e.g., layering, patterns), and ensuring the models reflect real-world constraints. With these behavioral and structural views complete, the project is well-prepared for scenario analysis, logic validation, and comprehensive quality assurance in the modules ahead.