{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/scalable-architecture/main/json-schema/scalable-architecture-event-schema.json",
  "title": "Domain Event",
  "description": "Describes a domain event in an event-driven scalable architecture, following CloudEvents conventions. Domain events enable loose coupling between microservices through async message passing over Kafka, RabbitMQ, or cloud message brokers.",
  "type": "object",
  "required": ["id", "source", "specversion", "type"],
  "properties": {
    "specversion": {
      "type": "string",
      "description": "CloudEvents specification version.",
      "const": "1.0"
    },
    "id": {
      "type": "string",
      "description": "Unique identifier for this event occurrence.",
      "format": "uuid",
      "example": "96fb5f0b-001e-0108-6d02-a85e0000000"
    },
    "source": {
      "type": "string",
      "description": "URI identifying the context in which the event occurred (typically the originating service).",
      "format": "uri",
      "example": "/orders/service"
    },
    "type": {
      "type": "string",
      "description": "Event type in reverse-DNS notation describing the kind of occurrence.",
      "pattern": "^[a-z][a-z0-9.]+$",
      "examples": [
        "com.example.orders.created",
        "com.example.payments.completed",
        "com.example.inventory.updated"
      ]
    },
    "subject": {
      "type": "string",
      "description": "Identifies the subject of the event in the context of the source (e.g., entity ID).",
      "example": "order-12345"
    },
    "datacontenttype": {
      "type": "string",
      "description": "Content type of the event data.",
      "default": "application/json",
      "examples": ["application/json", "application/avro"]
    },
    "dataschema": {
      "type": "string",
      "description": "URI identifying the schema for the event data payload.",
      "format": "uri"
    },
    "time": {
      "type": "string",
      "description": "Timestamp of when the event occurred in RFC3339 format.",
      "format": "date-time",
      "example": "2026-05-02T14:30:00Z"
    },
    "data": {
      "type": "object",
      "description": "Domain event payload specific to the event type.",
      "additionalProperties": true
    },
    "partitionkey": {
      "type": "string",
      "description": "Key used to route the event to a specific Kafka partition for ordering guarantees.",
      "example": "customer-456"
    },
    "correlationid": {
      "type": "string",
      "description": "Correlation ID for tracing a business transaction across multiple services.",
      "format": "uuid"
    },
    "causationid": {
      "type": "string",
      "description": "ID of the command or event that caused this event (event sourcing lineage).",
      "format": "uuid"
    },
    "metadata": {
      "type": "object",
      "description": "Additional metadata properties for routing, filtering, and tracing.",
      "properties": {
        "retryCount": {
          "type": "integer",
          "description": "Number of times this event has been retried.",
          "minimum": 0,
          "default": 0
        },
        "deadLetterQueue": {
          "type": "boolean",
          "description": "Whether this event has been moved to the dead letter queue.",
          "default": false
        },
        "version": {
          "type": "integer",
          "description": "Schema version for event evolution.",
          "minimum": 1,
          "default": 1
        }
      }
    }
  }
}