Protocol

Wire Format

All EDS messages are JSON text frames with the following envelope:

{
  "frameType": "<frame-type>",
  "framePayload": { ... }
}

frameType identifies the frame type. framePayload contains the frame-specific fields.

Frame Type Reference

Frame type	Direction	Description
EVENT	Server → Client	Delivers an event from the queue
ACK_EVENT	Client → Server	Acknowledges a received event
PING	Client → Server	Keep-alive probe
PONG	Server → Client	Keep-alive response
ERROR	Server → Client	Error occurs

---

EVENT

Fields

Field	Type	Description
eventId	string (UUID)	Stable identifier for this event. Identical across redeliveries of the same event. Use this for deduplication.
eventType	string	The type of event (e.g. TENANT_ONBOARDED).
receiptId	string	Identifies this specific delivery attempt. Changes on each redelivery. Use this in the ACK_EVENT frame.
eventTs	string (ISO 8601)	Timestamp when the event occurred.
queueName	string	The queue through which this event was delivered.
eventPayload	object	Event-specific data. Fields vary by eventType — see Events.

Example

{
  "frameType": "EVENT",
  "framePayload": {
    "eventId": "a1b2c3d4-0000-0000-0000-000000000001",
    "eventType": "TENANT_ONBOARDED",
    "receiptId": "f9e8d7c6-0000-0000-0000-000000000002",
    "eventTs": "2026-03-20T14:30:00.000Z",
    "queueName": "my-integration-queue",
    "eventPayload": {
      "tenantId": "P0001",
      "empegoTenantId": "tenant-abc"
    }
  }
}

---

ACK_EVENT

Fields

Field	Type	Description
receiptId	string	The receiptId from the EVENT frame being acknowledged.

Example

{
  "frameType": "ACK_EVENT",
  "framePayload": {
    "receiptId": "f9e8d7c6-0000-0000-0000-000000000002"
  }
}

---

PING

Fields

Field	Type	Description
correlationId	string (optional)	Client-chosen identifier to correlate the pong response.

Example

{
  "frameType": "PING",
  "framePayload": {
    "correlationId": "ping-001"
  }
}

---

PONG

Fields

Field	Type	Description
correlationId	string (optional)	Echo of the correlationId from the corresponding PING.

Example

{
  "frameType": "PONG",
  "framePayload": {
    "correlationId": "ping-001"
  }
}

---

ERROR

WIP: This is still in development and may change.

Fields

Field	Type	Description
message	string	Error message

Example

{
  "frameType": "ERROR",
  "framePayload": {
    "message": "Malformed websocket frame"
  }
}