Event Modeling

Definition

Event Modeling is a method for designing information systems by mapping what happens over time. It creates a linear blueprint that serves as the single source of truth for Product, Design, and Engineering.

Unlike static diagrams (like ERDs or UML) that focus on structure, Event Modeling focuses on the narrative of the system. It visualizes the system as a film strip, showing exactly how a user’s action impacts the system state and what information is displayed back to them.

Core Components

An Event Model is composed of four distinct elements:

• Commands (Blue): The intent or action initiated by the user (e.g., “Submit Order”).
• Events (Orange): A fact recorded by the system that cannot be changed (e.g., “OrderPlaced”). This is the single source of truth.
• Views (Green): Information displayed to the user, derived from previous events (e.g., “Order Confirmation Screen”).
• Processes: The logic or automation that reacts to events to trigger other commands or update views.

Why It Matters for AI

In modern software development, ambiguity is the enemy. While human engineers can infer intent from a loose visual mockup, AI models require explicit instructions.

Event Modeling forces implicit business rules to become explicit. By defining the exact data payload of every Command and the resulting state change of every Event, we provide AI agents with a deterministic roadmap. This ensures the generated code handles edge cases and data consistency correctly, rather than just “looking right” on the frontend.

Relationship to Requirements

Event Modeling acts as a bridge between Visual Design (what it looks like) and Technical Architecture (how it works).

It does not replace functional requirements; rather, it validates them. A feature is only considered “defined” when there is a complete path mapped from the user’s view, through the command, to the stored event, and back to the view. This “closed loop” guarantees that every pixel on the screen is backed by real data.