The primary class variables are get and set directly, e.g.:

eva.login = "operator";

API and Authentication

Authentication variables should set before start() method is called - either login/password or API key. If there is auth cookie set, API token variable is filled by the engine automatically.

  • login user login

  • password user password

  • xopts extra login options (EVA ICS v4 only)

  • apikey API key

  • client_id report a custom client id to the server (e.g. a custom-defined ID of the current UI page)

  • api_uri API URI (do not required if working in a web browser)

  • set_auth_cookies if true (default), auth cookie is used to store API token.

  • api_token current API token, filled automatically after login. Can be filled manually if obtained e.g. for an embedded JS HMI application.

Item processing, special

  • debug enable debug mode (1), enable verbose debug mode (2)

  • log.records set max. log records to retrieve from the server.

  • state_updates Possible values:

    • true (default) - get states of all items API key has access to

    • [ ‘oidmask1’, ‘oidmask2’ ] - (v4) specified subscriptions for EVA ICS v4 (e.g. ‘sensor:env/#’)

    • false - disable state updates

  • ws_mode use web sockets. Set automatically if WebSocket object is detected, can be set to “false” manually before engine start.

  • clear_unavailable if true, item state is set to null, if the one is no longer available on the back-end (default: false).

  • log_params log processing params

Read-only informational variables

  • version engine version

  • authorized_user current authorized user

  • logged_in boolean, set to true when user is logged in

  • ws engine web socket object

  • log.level current log level (for log processing)

  • log_level_names dictionary of log level names (code: name)

  • in_evaHI true if the engine runs in evaHI-based web client

  • server_info contains actual server info (output of API test method)

  • tsdiff time difference between client and server

Loading configuration

The engine has got a built-in method to load configuration JSON:

eva.load_config("path/to/config.json").then((_config) => start_your_hmi());

If the path is not specified, the engine tries to load config.json file from the path where the compiled JS is located.

The config has the following format:

  "engine": {
    "api_uri": "API_URI",
    "api_key": "SECRET",
    "debug": false,
    "login": "user",
    "password": "secret",
    "set_auth_cookies": true,
    "state_updates": true,
    "wasm": false,
    "ws_mode": true,
    "log_params": {
      "level": 20,
      "records": 200
    "interval": {
      "ajax_reload": 2,
      "log_reload": 2,
      "action_watch": 0.5,
      "heartbeat": 5,
      "reload": 5,
      "restart": 1,
      "ws_buf_ttl": 0

All the configuration fields are optional.