Server - Sentinel

Communications between Server and Sentinel are done with json via a websocket connection.

Message Format

All messages follow a consistent envelope structure:

Message Types

sentinel.register

Used to register a Sentinel when connecting to the server. This message must be the first message sent or the sentinel will be disconnected.

Direction: Sentinel -> Server

Payload:

Empty payload.

Example:

{
  "type": "sentinel.register",
  "timestamp": 1696969420,
  "payload": {}
}

server.registration.ack

This message will be sent from the server to acknowledge a registration of a sentinel.

Direction: Server -> Sentinel

Payload:

Example:

{
  "type": "server.registration.ack",
  "timestamp": 1696969420,
  "payload": {
    "sentinelId": "e0a1e92b-7aae-4885-b5f7-7f7a89fce101"
  }
}

server.registration.reject

This message will be sent from the server to reject the registration of a sentinel. If the sentinel receives this message, it should close the connection.

Direction: Server -> Sentinel

Payload:

Example:

{
  "type": "server.registration.reject",
  "timestamp": 1696969420,
  "payload": {
    "reason": "Server busy"
  }
}

server.set-resolution

Request a concrete resolution from the sentinel. The sentinel only receives a maxSidePx value and must preserve the original aspect ratio when scaling.

Direction: Server -> Sentinel

Payload:

Example:

{
  "type": "server.set-resolution",
  "timestamp": 1696969420,
  "payload": {
    "maxSidePx": 720
  }
}

sentinel.frame

The sentinel sends its frames every couple of seconds to the server.

Direction: Sentinel -> Server

Payload:

Example:

{
  "type": "sentinel.frame",
  "timestamp": 1696969420,
  "payload": {
    "frames": [
      {
        "sentinelId": "b255e355-e398-43d7-b772-101bbf4ca8f0",
        "frameId": "4799566e-ecdf-40e0-99c2-7bdc63a4038c",
        "index": 5,
        "data": "/9j/4AAQSkZ....Lj/1bP/F1v0A//9k="
      },
      {
        "sentinelId": "b255e355-e398-43d7-b772-101bbf4ca8f0",
        "frameId": "d7994246-35a6-4e2d-aae7-14bf9022f927",
        "index": 23,
        "data": "/9j/4AAQSkZJ....ejBknVXUhEj/9k="
      }
    ]
  }
}