Understanding Software Use Cases

Whether you’re a product manager defining requirements, a software architect designing the system, a software engineer implementing features, or a designer crafting user experiences, use cases are your shared language for describing how software should work. They bridge the gap between user needs and technical implementation.

What Are Use Cases?

Use cases describe how software should work and the interactions between the user and the software. They define potential scenarios of software usage in response to an external request.

The Collaborative Perspective

Collaboration is key to building software that meets user needs, and use cases are a powerful tool for this.

Let me walk you through a practical approach to identifying and documenting software use cases.

We’ll focus on:

  1. User Interactions: How will people use your software?
  2. System Requirements: What does the system need to do?
  3. Implementation Details: How does the software respond to each user interaction?

Here’s a concrete example of a user’s journey through a project management system:

journey title Project Creation section Begin Logs in: 5: User section Project Creation Clicks "New Project": 5: User Fills project details: 1: User section Completion Project Setup Complete: 5: User

System State Analysis

Before implementing use cases, analyze and document your system’s state.

A system’s state is its current state at the beginning of the use case. Defining the system state helps everyone understand the impact on existing users after implementing the use case.

stateDiagram-v2 [*] --> LoggedOut LoggedOut --> LoggedIn: Authentication LoggedIn --> ProjectCreation: Initiate Project ProjectCreation --> ProjectComplete: Save Project ProjectComplete --> [*]

Mermaid is an excellent tool for creating diagrams. Use the stateDiagram-v2 syntax to create a diagram of the system’s state. Store your use case documentation as Markdown to render it in a web browser, GitHub, or other Markdown-compatible platforms.

stateDiagram-v2
    [*] --> LoggedOut
    LoggedOut --> LoggedIn: Authentication
    LoggedIn --> ProjectCreation: Initiate Project
    ProjectCreation --> ProjectComplete: Save Project
    ProjectComplete --> [*]

Now is a great time to create a documentation hub for the team. This will keep everyone on the same page as the software evolves to meet user needs. This documentation hub can be a wiki, a shared folder, or a dedicated website.

Use Case Documentation Guide

1. Use Case Template

Here’s a template that can be used by both technical and non-technical team members. It’s a good idea to have a template for use cases that anyone impacted by the software changes can understand.

# Use Case: [Name]

## Business Requirements
* User Goal: [What the user wants to achieve]
* Business Value: [Why this matters]
* Success Criteria: [How we know it works]

## Technical Requirements
* System State: [Current state]
* Dependencies: [Required services/components]
* Data Requirements: [Input/Output specifications]

## Implementation Flow
1. Preconditions
   * [System state requirements]
   * [User permissions]

2. Main Flow
   * [System state changes]
   * [Data persistence requirements]

3. Postconditions
   * [System state changes]
   * [Data persistence requirements]

## Error Handling
* [Error scenarios]
* [Recovery procedures]

## Performance Considerations
* [Response time requirements]
* [Resource constraints]

Best Practices for Teams

  1. Collaboration

    • Involve all stakeholders in the use case definition.
    • Use clear, shared language.
    • Document assumptions and constraints.

  2. Error Handling

    • Define clear error types.
    • Plan for user-friendly error messages.
    • Consider recovery strategies.

  3. Testing Strategy

    • Write tests for each use case.
    • Consider edge cases and error states.
    • Plan for user feedback.
    • Design for accessibility.

Common Pitfalls

  1. Communication Gaps

    • Avoid technical jargon without explanation.
    • Ensure shared understanding across teams.
    • Document decisions and their rationale.

  2. Scope Management

    • Keep use cases focused and manageable.
    • Consider dependencies between use cases.
    • Plan for iterative development.

  3. User Experience

    • Consider edge cases and error states.
    • Plan for user feedback.
    • Design for accessibility.

Implementation Checklist

  • Define clear user goals.
  • Document technical requirements.
  • Plan error handling.
  • Obsess over the user experience.
  • Write tests.
  • Document decisions.
  • Monitoring plan.

Next Steps

Use cases are the epicenter of the software development process. After all, what else is software for except to serve people? Building software with user problems at the center of the process will lead to the best software experiences.

For more on building software together, check out:

References