Use Case Analysis
About
Use Case Analysis is the process of identifying, describing, and understanding how users or other systems interact with our system to achieve specific goals. In System Design, it helps bridge the gap between business needs and technical implementation by turning high-level requirements into practical interaction scenarios.
Think of it as a storyboard for our system—showing who uses it, what they do, and how the system responds.
In System Design, use case analysis ensures that our architecture isn’t just technically sound—it’s aligned with how people and systems will actually use it.
Why It Matters in System Design ?
Clarifies Functional Requirements
Helps ensure that all necessary features and interactions are captured before designing the architecture.
Identifies Edge Cases Early
Forces us to think about alternative flows, error scenarios, and unusual usage patterns.
Aligns Business & Technical Teams
Product managers, designers, and engineers can all refer to the same use case document.
Supports Test Planning
Test cases can be derived directly from use cases, ensuring coverage for critical flows.
Informs Design Decisions
Understanding how a system will be used helps us choose the right architecture, scaling strategy, and data model.
The Use Case Analysis Process
1. Identify the Actors
Actors can be:
Primary actors – Directly interact with the system (e.g., user, admin, mobile app).
Secondary actors – Provide services to the system (e.g., payment gateway, notification service).
Example For an e-commerce checkout flow:
Primary actor: Shopper
Secondary actor: Payment processor, inventory service
2. Define the Goal
Clearly state what the actor wants to achieve in this interaction.
Keep it simple and user-focused.
Example Goal: “Complete a purchase and receive confirmation.”
3. Describe the Main Success Scenario
Step-by-step outline of how the interaction proceeds when everything works as intended.
Example
Shopper adds items to cart.
Shopper proceeds to checkout.
System displays order summary.
Shopper enters payment details.
Payment is processed successfully.
System confirms the order and sends email confirmation.
4. Document Alternative Flows
Not every interaction is perfect—document variations and optional paths.
Example
Shopper updates the shipping address mid-checkout.
Shopper uses a coupon code.
5. Capture Exception Scenarios
Identify failure cases and how the system responds.
Example
Payment fails due to insufficient funds → System prompts user to retry or choose another payment method.
Item goes out of stock before checkout → System alerts user and updates the cart.
6. Specify Preconditions and Postconditions
Preconditions – What must be true before the use case starts. Example: User must be logged in.
Postconditions – What will be true after the use case completes successfully. Example: Order is stored in the database, and inventory is updated.
7. Validate with Stakeholders
Review use cases with:
Product managers (to confirm business logic)
Engineers (to confirm technical feasibility)
QA testers (to ensure testability)
Best Practices
Use clear, simple language - avoid overly technical terms in the main scenario.
Keep use cases solution-agnostic; focus on what the system does, not how it’s implemented.
Number the steps for easy reference.
Don’t skip failure scenarios - they often have huge design implications.
Last updated