Orders — event contract

binding spec asyncapi/orders.asyncapi.yaml @ 3.0.0 is the spec of record. It states what must be; implementations converge on it, never the reverse.

Enforced by

• any change must bump the artifact and service versions (check:version); a silent edit fails CI
• a breaking change must take a major version (check:compat)
• Spectral lint, house naming rules included
• Microcks contract tests hold mocks and implementations to these messages

Version history

Version	First released	Service version
3.0.0	2026-08-27	3.0.0
2.1.0	2026-08-24	2.1.0
2.0.0	2026-08-23	2.0.0
1.5.0	2026-08-23	1.0.0

Consume it

• Agents, over MCP: get_artifact('orders', 'asyncapi/orders.asyncapi.yaml')
• Raw spec: asyncapi/orders.asyncapi.yaml
• Implementations pin the release tag orders/v3.4.0 in their contracts.lock and fetch read-only; the full loop is on Drive an implementation.

orders.placed.v2

Emitted when an order is accepted and persisted.

Produced by Orders — consumed by Payments.

sequenceDiagram
    autonumber
    participant orders as Orders
    participant chan as orders.placed.v2
    participant payments as Payments
    orders-)chan: OrderPlaced
    Note right of chan: com.hungovercoders.orders.placed.v2
    chan--)payments: OrderPlaced

OrderPlaced

Order placed

Event type com.hungovercoders.orders.placed.v2

Payload (data)

Field	Type	Required	Constraints
order_id	string (uuid)	required	—
customer_id	string (uuid)	required	—
placed_at	string (date-time)	required	—
total_pence	integer	required	≥ 0

CloudEvents envelope

Field	Type	Required	Constraints
specversion	string	required	always '1.0'
id	string (uuid)	required	—
source	string	required	always '/orders'
type	string	required	always 'com.hungovercoders.orders.placed.v2'
subject	string (uuid)	required	—
time	string (date-time)	required	—
datacontenttype	string	required	always 'application/json'

Example events (Microcks fixtures)

placed

{
  "specversion": "1.0",
  "id": "aaaaaaaa-1111-4111-8111-aaaaaaaaaaaa",
  "source": "/orders",
  "type": "com.hungovercoders.orders.placed.v2",
  "subject": "11111111-1111-1111-1111-111111111111",
  "time": "2026-08-23T09:00:00Z",
  "datacontenttype": "application/json",
  "data": {
    "order_id": "11111111-1111-1111-1111-111111111111",
    "customer_id": "22222222-2222-2222-2222-222222222222",
    "placed_at": "2026-08-23T09:00:00Z",
    "total_pence": 2500
  }
}

orders.cancelled.v2

Emitted when an order is cancelled, with the reason.

Produced by Orders — no consumer in the specs yet.

sequenceDiagram
    autonumber
    participant orders as Orders
    participant chan as orders.cancelled.v2
    orders-)chan: OrderCancelled
    Note right of chan: com.hungovercoders.orders.cancelled.v2
    Note over chan: no consumer in the specs yet

OrderCancelled

Order cancelled

Event type com.hungovercoders.orders.cancelled.v2

Payload (data)

Field	Type	Required	Constraints
order_id	string (uuid)	required	—
cancelled_at	string (date-time)	required	—
reason	string	required	one of customer_request, payment_failed, out_of_stock

CloudEvents envelope

Field	Type	Required	Constraints
specversion	string	required	always '1.0'
id	string (uuid)	required	—
source	string	required	always '/orders'
type	string	required	always 'com.hungovercoders.orders.cancelled.v2'
subject	string (uuid)	required	—
time	string (date-time)	required	—
datacontenttype	string	required	always 'application/json'

Example events (Microcks fixtures)

cancelled

{
  "specversion": "1.0",
  "id": "bbbbbbbb-2222-4222-8222-bbbbbbbbbbbb",
  "source": "/orders",
  "type": "com.hungovercoders.orders.cancelled.v2",
  "subject": "33333333-3333-3333-3333-333333333333",
  "time": "2026-08-23T09:05:00Z",
  "datacontenttype": "application/json",
  "data": {
    "order_id": "33333333-3333-3333-3333-333333333333",
    "cancelled_at": "2026-08-23T09:05:00Z",
    "reason": "customer_request"
  }
}

Full rendered contract