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API

There are three API available in Dashkiosk:

  • a REST API to manipulate groups, dashboards and displays,
  • the change API which is a Socket.IO based API which broadcasts changes to subscriber,
  • the display API which is a Socket.IO based API which tells displays which URL they should display.

There is also an internal bus API.

REST API

The REST API is available on the /api endpoint. Only JSON is currently supported. On error, the HTTP error code is important and the error message is also encapsulated into a JSON object:

{
    "error": {
        "httpCode": 404,
        "message": "No display named \"CNDS0KD\".",
        "name": "NotFoundError",
        "stack": [
            "NotFoundError: No display named \"CNDS0KD\".",
            "    at dashkiosk/lib/models/display.js:154:15",
            "    at process._tickDomainCallback (node.js:459:13)",
            "    at process._tickFromSpinner (node.js:390:15)",
            "From previous event:",
            "    at new Promise (dashkiosk/node_modules/sequelize/node_modules/bluebird/js/main/promise.js:88:37)",
            "    at module.exports.CustomEventEmitter.then (dashkiosk/node_modules/sequelize/lib/emitters/custom-event-emitter.js:144:12)",
            "    at Function.Display.get (dashkiosk/lib/models/display.js:152:6)",
            "    at dashkiosk/lib/api/rest/displays.js:21:20",
            "    at callbacks (dashkiosk/node_modules/express/lib/router/index.js:164:37)",
            "    at param (dashkiosk/node_modules/express/lib/router/index.js:138:11)"
        ]
    },
    "message": "No display named \"CNDS0KD\".",
    "token": "1397254337651-5YHK0SFJRC"
}

The error attribute is only present in development mode. It can also be found in the logs thanks to the token attribute.

Displays

Groups

Dashboards

Changes API

The socket.IO endpoint for this API is changes. Upon connection, a client will get all the current groups. Each group has a collection of displays in the displays attribute and an array of dashboards in the dashboards attribute. Here is an example:

{
  "1": {
      "description": "Default group for unassigned displays", 
      "id": 1, 
      "name": "Unassigned",
      "displays": {},
      "dashboards": []
  }, 
  "2": {
      "description": "Dashboards with Game of Thrones stuff", 
      "id": 2, 
      "name": "Game of Thrones"
      "displays": {
         "CNDS0K": {
            "connected": true,
            "description": "Nexus 5 (localhost:9400)", 
            "group": 10, 
            "id": 5, 
            "ip": null, 
            "name": "CNDS0K", 
            "viewport": "1920x1080"
         }
       }
      "dashboards": [
            {
              "active": false,
              "description": "House Stark",
              "group": 2,
              "id": 2,
              "timeout": 30,
              "url": "http://www.gameofthronescountdown.com/#stark",
              "viewport": null
            },
            {
              "active": true,
              "description": "House Tully",
              "group": 2,
              "id": 3,
              "timeout": 30,
              "url": "http://www.gameofthronescountdown.com/#tully",
              "viewport": null
            }
      ]
  }
}

This message will be labeled snapshot.

On changes, only the group or the display affected by the change will be sent. The label of the message will be one of:

  • group.deleted
  • group.updated
  • group.created

And for displays:

  • display.deleted
  • display.updated (also for new displays)

If a change affects a dashboard, the whole group will be sent nonetheless.

Display API

This API is used by the display to know what they should do. The socket.IO endpoint to use for it is displays.

The server attributes to each new display a serial number. The display is expected to remember it and transmit it back on the next connection. It is encrypted by the server to avoid the display to steal another display identity.

Upon connection, a display is expected to send a register message with an object containing the blob attribute with the encrypted identity it previously received (if any).

If the server accepts the identity as is, it answers to this message with the same blob that should be stored by the client. If not, it will generate a new blob and sends it back to the client. In both cases, the client just has to store the received blob.

After this handshake, the display can receive the following messages:

dashboard

The dashboard that should be displayed right now. It is an object containing the same attributes as we would have got when requesting this particular dashboard with the REST API. See getdashboard.

reload

The display should reload itself.

osd

The OSD should be shown or hidden. If the message comes with a text, the OSD is displayed with the provided text. Otherwise, it is hidden.

viewport

Modify the current viewport of the display with the provided value.

Internal bus message

To avoid strong coupling between components, Dashkiosk uses postal.js as an internal bus message. The messages that are emitted are listed below:

  • display.NAME.connected when a new display is connected
  • display.NAME.disconnected when a new display is disconnected
  • display.NAME.group when a display should change to a new group
  • display.NAME.deleted when a display is deleted
  • display.NAME.updated when another change happens on a display
  • display.NAME.dashboard when a new dashboard should be displayed by the given display.
  • display.NAME.reload when a display should reload itself
  • display.NAME.osd when we need to display something on the OSD
  • display.NAME.viewport when the display viewport should be updated
  • group.ID.created when a new group is created
  • group.ID.updated when a group is updated (but not something dashboard related)
  • group.ID.deleted when a group is deleted
  • group.ID.dashboard when a whole group should switch to a new dashboard
  • group.ID.dashboard.ID.added when a new dashboard has been added
  • group.ID.dashboard.ID.removed when a dashboard has been removed
  • group.ID.dashboard.ID.updated when a dashboard has been updated

Each message comes with the group, the dashboard and/or the display specified in the message (when this is relevant).