Event Payload Schemas

This reference provides standardized schemas and examples for common event types in Hook0. Following these schemas ensures consistency and compatibility across integrations.

Event Type Naming Convention

Hook0 uses a three-part naming convention for event types:

service.resource.verb

• service: The service or domain (e.g., user, order, payment)
• resource: The specific resource or entity (e.g., account, payment, subscription)
• verb: The action in past tense (e.g., created, updated, deleted, completed)

Examples:

• user.account.created - A user account was created
• order.payment.completed - An order payment was completed
• inventory.stock.updated - Inventory stock was updated
• subscription.plan.canceled - A subscription plan was canceled

Anti-patterns (avoid 2-part names):

• ❌ user.created → ✅ user.account.created
• ❌ order.paid → ✅ order.payment.completed
• ❌ file.uploaded → ✅ storage.file.uploaded

Schema Format

Hook0 events follow this structure:

{
  "application_id": "string (UUID, required)",
  "event_id": "string (UUID, optional; server generates UUIDv7 if omitted)",
  "event_type": "string (required, e.g. user.account.created)",
  "payload": "string (required; for JSON, send the stringified object shown in the examples below)",
  "payload_content_type": "string (required; application/json, text/plain, or application/octet-stream+base64)",
  "labels": "object (required; string keys and values)",
  "metadata": "object (optional; string keys and values)",
  "occurred_at": "string (ISO 8601, required)"
}

The examples below show each event's payload as a JSON object for readability. A real ingestion request sends payload as a string (with payload_content_type: application/json) alongside application_id, labels, and occurred_at, as listed above. See events for the full ingestion contract.

User Lifecycle Events

user.account.created

Emitted when a new user account is created.

Schema:

interface UserCreatedPayload {
  user_id: string;
  email: string;
  name: string;
  username?: string;
  plan?: string;
  email_verified: boolean;
  created_at: string; // ISO 8601
  metadata?: Record<string, any>;
}

Example:

{
  "event_id": "0190f3c2-7a1d-7b2e-8c3f-4d5e6f708192",
  "event_type": "user.account.created",
  "payload": {
    "user_id": "user_12345",
    "email": "[email protected]",
    "name": "John Doe",
    "username": "johndoe",
    "plan": "free",
    "email_verified": false,
    "created_at": "2024-01-15T10:30:00Z",
    "metadata": {
      "signup_source": "web",
      "referrer": "google",
      "campaign": "winter_2024"
    }
  },
  "labels": {
    "environment": "production",
    "source": "auth_service",
    "priority": "normal"
  },
  "occurred_at": "2024-01-15T10:30:01Z"
}

user.account.updated

Emitted when user profile information is modified.

Schema:

interface UserUpdatedPayload {
  user_id: string;
  changes: string[]; // Array of changed fields
  previous_values?: Record<string, any>;
  updated_fields: Record<string, any>;
  updated_at: string; // ISO 8601
}

Example:

{
  "event_id": "0190f3c3-8b2e-7c3f-9d40-5e6f70819203",
  "event_type": "user.account.updated",
  "payload": {
    "user_id": "user_12345",
    "changes": ["name", "plan"],
    "previous_values": {
      "name": "John D.",
      "plan": "free"
    },
    "updated_fields": {
      "name": "John Doe",
      "plan": "pro"
    },
    "updated_at": "2024-01-15T14:20:00Z"
  },
  "labels": {
    "environment": "production",
    "source": "user_service"
  },
  "occurred_at": "2024-01-15T14:20:01Z"
}

user.account.deleted

Emitted when a user account is deleted.

Schema:

interface UserDeletedPayload {
  user_id: string;
  email: string;
  deleted_at: string; // ISO 8601
  deletion_reason?: string;
  soft_delete: boolean;
  retention_period_days?: number;
}

Example:

{
  "event_id": "0190f3c4-9c3f-7d40-a51e-6f7081920314",
  "event_type": "user.account.deleted",
  "payload": {
    "user_id": "user_12345",
    "email": "[email protected]",
    "deleted_at": "2024-01-15T18:45:00Z",
    "deletion_reason": "user_request",
    "soft_delete": true,
    "retention_period_days": 30
  },
  "labels": {
    "environment": "production",
    "source": "user_service",
    "priority": "high"
  },
  "occurred_at": "2024-01-15T18:45:01Z"
}

user.email.verified

Emitted when a user verifies their email address.

Schema:

interface UserEmailVerifiedPayload {
  user_id: string;
  email: string;
  verified_at: string; // ISO 8601
  verification_method: 'email_link' | 'code' | 'magic_link';
}

Example:

{
  "event_id": "0190f3c5-ad40-7e51-b62f-708192031425",
  "event_type": "user.email.verified",
  "payload": {
    "user_id": "user_12345",
    "email": "[email protected]",
    "verified_at": "2024-01-15T11:15:00Z",
    "verification_method": "email_link"
  },
  "labels": {
    "environment": "production",
    "source": "auth_service"
  },
  "occurred_at": "2024-01-15T11:15:01Z"
}

Subscription and Billing Events

subscription.plan.created

Emitted when a new subscription is created.

Schema:

interface SubscriptionCreatedPayload {
  subscription_id: string;
  user_id: string;
  customer_id?: string;
  plan: string;
  status: 'trialing' | 'active' | 'past_due' | 'canceled' | 'unpaid';
  billing_cycle: 'monthly' | 'yearly' | 'weekly' | 'daily';
  amount: number;
  currency: string;
  trial_end?: string; // ISO 8601
  current_period_start: string; // ISO 8601
  current_period_end: string; // ISO 8601
  created_at: string; // ISO 8601
}

Example:

{
  "event_id": "0190f3c6-be51-7f62-8a30-819203142536",
  "event_type": "subscription.plan.created",
  "payload": {
    "subscription_id": "sub_67890",
    "user_id": "user_12345",
    "customer_id": "cus_stripe_abc123",
    "plan": "pro_monthly",
    "status": "trialing",
    "billing_cycle": "monthly",
    "amount": 2999,
    "currency": "USD",
    "trial_end": "2024-01-29T10:30:00Z",
    "current_period_start": "2024-01-15T10:30:00Z",
    "current_period_end": "2024-02-15T10:30:00Z",
    "created_at": "2024-01-15T10:30:00Z"
  },
  "labels": {
    "environment": "production",
    "source": "billing_service",
    "priority": "high"
  },
  "occurred_at": "2024-01-15T10:30:01Z"
}

subscription.plan.updated

Emitted when subscription details change.

Schema:

interface SubscriptionUpdatedPayload {
  subscription_id: string;
  user_id: string;
  changes: string[];
  previous_values: Record<string, any>;
  updated_fields: Record<string, any>;
  updated_at: string; // ISO 8601
}

subscription.plan.canceled

Emitted when a subscription is canceled.

Schema:

interface SubscriptionCanceledPayload {
  subscription_id: string;
  user_id: string;
  canceled_at: string; // ISO 8601
  cancellation_reason?: string;
  effective_date: string; // ISO 8601
  immediate: boolean;
}

payment.transaction.succeeded

Emitted when a payment is successfully processed.

Schema:

interface PaymentSucceededPayload {
  payment_id: string;
  subscription_id?: string;
  user_id: string;
  amount: number;
  currency: string;
  payment_method: string;
  provider: string;
  provider_payment_id: string;
  processed_at: string; // ISO 8601
  metadata?: Record<string, any>;
}

Example:

{
  "event_id": "0190f3c7-cf62-7a73-9b41-920314253647",
  "event_type": "payment.transaction.succeeded",
  "payload": {
    "payment_id": "pay_12345",
    "subscription_id": "sub_67890",
    "user_id": "user_12345",
    "amount": 2999,
    "currency": "USD",
    "payment_method": "card",
    "provider": "stripe",
    "provider_payment_id": "pi_stripe_xyz789",
    "processed_at": "2024-01-15T10:30:00Z",
    "metadata": {
      "card_last4": "4242",
      "card_brand": "visa"
    }
  },
  "labels": {
    "environment": "production",
    "source": "payment_service",
    "priority": "high"
  },
  "occurred_at": "2024-01-15T10:30:01Z"
}

payment.transaction.failed

Emitted when a payment fails.

Schema:

interface PaymentFailedPayload {
  payment_id: string;
  subscription_id?: string;
  user_id: string;
  amount: number;
  currency: string;
  payment_method: string;
  provider: string;
  error_code: string;
  error_message: string;
  failed_at: string; // ISO 8601
  retry_count: number;
  next_retry_at?: string; // ISO 8601
}

Example:

{
  "event_id": "0190f3c8-da73-7b84-ac52-031425364758",
  "event_type": "payment.transaction.failed",
  "payload": {
    "payment_id": "pay_12346",
    "subscription_id": "sub_67890",
    "user_id": "user_12345",
    "amount": 2999,
    "currency": "USD",
    "payment_method": "card",
    "provider": "stripe",
    "error_code": "card_declined",
    "error_message": "Your card was declined",
    "failed_at": "2024-01-15T10:30:00Z",
    "retry_count": 1,
    "next_retry_at": "2024-01-16T10:30:00Z"
  },
  "labels": {
    "environment": "production",
    "source": "payment_service",
    "priority": "critical"
  },
  "occurred_at": "2024-01-15T10:30:01Z"
}

E-commerce Events

order.purchase.created

Emitted when a new order is placed.

Schema:

interface OrderCreatedPayload {
  order_id: string;
  customer_id: string;
  status: 'pending' | 'confirmed' | 'processing' | 'shipped' | 'delivered' | 'canceled';
  items: Array<{
    product_id: string;
    variant_id?: string;
    quantity: number;
    price: number;
    currency: string;
    name: string;
  }>;
  subtotal: number;
  tax: number;
  shipping: number;
  total: number;
  currency: string;
  shipping_address: {
    name: string;
    street: string;
    city: string;
    state: string;
    zip: string;
    country: string;
  };
  billing_address?: {
    name: string;
    street: string;
    city: string;
    state: string;
    zip: string;
    country: string;
  };
  created_at: string; // ISO 8601
}

Example:

{
  "event_id": "0190f3c9-eb84-7c95-8d63-142536475869",
  "event_type": "order.purchase.created",
  "payload": {
    "order_id": "ord_98765",
    "customer_id": "user_12345",
    "status": "pending",
    "items": [
      {
        "product_id": "prod_111",
        "variant_id": "var_111_xl",
        "quantity": 2,
        "price": 2999,
        "currency": "USD",
        "name": "Premium T-Shirt - XL"
      }
    ],
    "subtotal": 5998,
    "tax": 480,
    "shipping": 500,
    "total": 6978,
    "currency": "USD",
    "shipping_address": {
      "name": "John Doe",
      "street": "123 Main St",
      "city": "San Francisco",
      "state": "CA",
      "zip": "94105",
      "country": "US"
    },
    "created_at": "2024-01-15T10:30:00Z"
  },
  "labels": {
    "environment": "production",
    "source": "order_service"
  },
  "occurred_at": "2024-01-15T10:30:01Z"
}

order.shipment.shipped

Emitted when an order is shipped.

Schema:

interface OrderShippedPayload {
  order_id: string;
  customer_id: string;
  tracking_number: string;
  carrier: string;
  tracking_url?: string;
  shipped_at: string; // ISO 8601
  estimated_delivery?: string; // ISO 8601
  shipping_address: {
    name: string;
    street: string;
    city: string;
    state: string;
    zip: string;
    country: string;
  };
}

Example:

{
  "event_id": "0190f3ca-fc95-7da6-9e74-25364758697a",
  "event_type": "order.shipment.shipped",
  "payload": {
    "order_id": "ord_98765",
    "customer_id": "user_12345",
    "tracking_number": "1Z999AA1234567890",
    "carrier": "UPS",
    "tracking_url": "https://www.ups.com/track?tracknum=1Z999AA1234567890",
    "shipped_at": "2024-01-16T14:20:00Z",
    "estimated_delivery": "2024-01-18T17:00:00Z",
    "shipping_address": {
      "name": "John Doe",
      "street": "123 Main St",
      "city": "San Francisco",
      "state": "CA",
      "zip": "94105",
      "country": "US"
    }
  },
  "labels": {
    "environment": "production",
    "source": "fulfillment_service",
    "priority": "normal"
  },
  "occurred_at": "2024-01-16T14:20:01Z"
}

order.shipment.delivered

Emitted when an order is successfully delivered.

Schema:

interface OrderDeliveredPayload {
  order_id: string;
  customer_id: string;
  tracking_number: string;
  carrier: string;
  delivered_at: string; // ISO 8601
  signature_required: boolean;
  signed_by?: string;
  delivery_notes?: string;
}

Product and Inventory Events

shop.product.created

Emitted when a new product is added to the catalog.

Schema:

interface ProductCreatedPayload {
  product_id: string;
  name: string;
  description: string;
  category: string;
  brand?: string;
  sku: string;
  price: number;
  currency: string;
  inventory_quantity?: number;
  status: 'active' | 'draft' | 'archived';
  images?: string[];
  attributes?: Record<string, any>;
  created_at: string; // ISO 8601
}

shop.inventory.low

Emitted when product inventory falls below threshold.

Schema:

interface InventoryLowPayload {
  product_id: string;
  variant_id?: string;
  sku: string;
  current_quantity: number;
  threshold: number;
  location?: string;
  supplier?: string;
  reorder_point: number;
  checked_at: string; // ISO 8601
}

System and Infrastructure Events

system.maintenance.started

Emitted when system maintenance begins.

Schema:

interface MaintenanceStartedPayload {
  maintenance_id: string;
  title: string;
  description: string;
  affected_services: string[];
  started_at: string; // ISO 8601
  estimated_end_at?: string; // ISO 8601
  severity: 'low' | 'medium' | 'high' | 'critical';
  maintenance_type: 'scheduled' | 'emergency';
}

system.error.emitted

Emitted when system errors occur.

Schema:

interface SystemErrorPayload {
  error_id: string;
  service: string;
  error_type: string;
  message: string;
  stack_trace?: string;
  user_id?: string;
  request_id?: string;
  severity: 'low' | 'medium' | 'high' | 'critical';
  occurred_at: string; // ISO 8601
  metadata?: Record<string, any>;
}

Custom Event Schemas

Creating Custom Schemas

When creating custom event types, follow these guidelines:

1. Use descriptive names: service.resource.action format (e.g., document.file.shared, calendar.meeting.scheduled)
2. Include timestamps: Always include relevant timestamp fields
3. Provide context: Include sufficient context for downstream processing
4. Use consistent data types: Maintain consistency across similar events
5. Version your schemas: Plan for schema evolution

Example Custom Event:

interface DocumentSharedPayload {
  document_id: string;
  document_title: string;
  owner_id: string;
  shared_with: Array<{
    user_id: string;
    email: string;
    permission: 'read' | 'write' | 'admin';
  }>;
  shared_at: string; // ISO 8601
  expiry_date?: string; // ISO 8601
  access_link?: string;
  message?: string;
}

Schema Validation

Hook0 supports JSON Schema validation for event payloads:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "user_id": {
      "type": "string",
      "pattern": "^user_[a-zA-Z0-9]{10,}$"
    },
    "email": {
      "type": "string",
      "format": "email"
    },
    "created_at": {
      "type": "string",
      "format": "date-time"
    }
  },
  "required": ["user_id", "email", "created_at"],
  "additionalProperties": false
}

Best Practices

Payload Design

• Keep payloads focused and avoid unnecessary data
• Use ISO 8601 format for all timestamps
• Include unique identifiers for all entities
• Use consistent field naming conventions
• Provide meaningful descriptions and context

Data Types

• Use appropriate data types (strings for IDs, numbers for amounts)
• Include currency information with monetary amounts
• Use enums for status fields with known values
• Include units for measurements

Backwards Compatibility

• Add new fields as optional
• Never remove existing required fields
• Use semantic versioning for major schema changes
• Provide migration guides for breaking changes

Documentation

• Document all fields and their purposes
• Provide example payloads
• Explain business context and use cases
• Include validation rules and constraints

For more information on implementing these schemas in your applications, see our Integration Guides and SDK Documentation.