Notre avis

Guide pour concevoir des modèles d'événements et rédiger des Event Models au format Event Modeler, en suivant une méthodologie en 7 étapes.

Points forts

Approche structurée avec étapes claires et format normalisé
Intègre la modélisation des commandes, événements et vues
Inclut un stream d'événements append-only pour la traçabilité
Définit des slices comme unités de travail livrables

Limites

Nécessite une bonne compré préalable du domain-driven design
Le format ASCII pour les wireframes peut être limité
Ne couvre pas l'implémentation technique détaillée

Quand l'utiliser

À utiliser lors de la phase de conception d'un système événementiel pour structurer les échanges métier et aligner les parties prenantes.

Quand l'éviter

Évitez pour des projets très simples sans complexité événementielle ou lorsque l'équipe n'est pas familiarisée avec les concepts d'event modeling.

Exemples

Shopping Cart Event Model

Create an event model for an e-commerce shopping cart system using the /event-model-plan methodology. Include slices for adding items, updating quantities, and placing an order. Provide the emlang blocks and event stream.

User Registration Event Stream

Design an event model for user registration with event stream entries. Include commands like RegisterUser, events like UserRegistered, and views like UserProfile. Show the frontmatter and traceability.

/event-model-plan — Event Modeling & Event Model Format

You are helping design event models and write Event Models for EventModeler. Follow the Event Modeling methodology and the Event Model format defined in docs/product-spec.md.

Event Modeling Workshop (7 Steps)

Brainstorm — Capture all domain events (past-tense: UserRegistered, OrderPlaced)
Plot — Arrange events chronologically on a timeline (left to right)
Storyboard — Add wireframes above the timeline showing what users see
Inputs — Add Commands linking user actions to Events (RegisterUser → UserRegistered)
Outputs — Add Views showing what data users see after events (UserProfile, Dashboard)
Organize — Define swimlanes for actors and bounded contexts
Elaborate — Define Given/When/Then scenarios for complex business logic

Slice Definition

A slice is a vertical unit of work: Trigger → Command → Event → View.

Use emlang notation:

slices:
  SliceName:
    steps:
      - t: Actor/TriggerScreen       # Wireframe/trigger
      - c: CommandName                # Command
        props:
          field: type
      - e: Context/EventName          # Event
        props:
          field: type
      - v: ViewName                   # View/read model
    tests:
      HappyPath:
        when:
          - c: CommandName
            props:
              field: value
        then:
          - e: Context/EventName
      ErrorCase:
        given:
          - e: Context/SomeEvent
        when:
          - c: CommandName
        then:
          - x: ErrorName

Event Model Format

Structure

---
title: "Feature Name"
status: draft | modeling | refined | approved
domain: "Bounded Context"
version: 1
---

# Feature Name
## Overview
## Key Ideas
## Slices
### Slice: Name
(emlang block)
## Scenarios
## Data Flows
## Dependencies
## Sources
<!-- event-stream -->
## Event Stream
(eventstream blocks)

Event Stream

Append-only log at the bottom of Event Model files. Each event is a fenced eventstream block:

seq: 1
ts: "2026-02-21T10:00:00Z"
type: EventModelCreated
actor: user@example.com
data:
  title: "Feature Name"
  status: draft

Key Rules

Emlang blocks: one per slice, under ### Slice: heading
Event stream: append-only, never modify existing blocks
Frontmatter status tracks Event Model lifecycle: draft → modeling → refined → approved
Wireframes are ASCII art (plain text, no images)

Guidance

When helping design event models:

Start with domain events — what happens in the business?
Group events into slices — each slice is a deliverable unit
Define commands — what action triggers each event?
Add views — what does the user see after each event?
Write scenarios — Given (preconditions) / When (command) / Then (outcomes)
Check completeness — every view field must trace back to an event field, which traces to a command field

Modélisation d'événements & Format Event Model

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