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Websockets

Once you form a WebSocket connection to a server, JSON objects will be passed between them. Every message in either direction will have a $ key to specify the purpose of the message.

Here we define the specifications of these messages:

Messages from the Client​

sub - Subscribe to Model(s)​

A subscription requests the server to send the current value for these model paths, and continue to send new values until the unsub message is sent.

  • $: "sub"
  • keys: string[] - The model paths to subscribe to

unsub - Unsubscribe from Model(s)​

The user no longer to see these values. This requests the server to cease additional updates for these model paths

  • $: "unsub"
  • keys: string[] - The model paths to unsubscribe to

evt - Event​

The component has called an event definition and the client is reporting it to the server. This message conforms exactly to the event request definition

  • $: "evt"
  • key: string - A unique identifier for this event, as determined by the client
  • event: { - object of event details, containing the following keys:
    • modelState: JSONValue - the event definition
    • payload: JSONValue - the data coming from the component
    • target: { - object detailing the source of the event, containing:
      • key?: string
      • component: string
      • propKey: string
      • path: (string|number)[]

Messages from the Server​

up - Model Value Update​

The model value has changed or a subscription has begun. This event sends the current state of a model from the server to the client

  • $: "up"
  • key: string - The model path that has changed or is being provided
  • val: JSONValue - The JSON value of the model

evt-res - Respond to an Event​

The server is replying to an event that previously came from the client. This allows the client to resolve an async handler that is passed into the client component.

  • $: "evt-res"
  • key: string - The key of the $:evt that was sent to the server
  • res: { - Object detailing the response
    • $: 'response'
    • error?: boolean - If this is an error that should be thrown, or a valid response
    • payload?: JSONValue - Data sent by the server function
    • actions?: ActionModelState[] - Actions that the client should call as a result of this server-handled event

Note: the res field seems redundant and these fields should probably be flattened out into evt-res