Advanced usage

Multi-page interfaces, external authentication

The primary page

If multi-page navigation contains links back to the main page, it should perform a single authentication attempt to re-use an existing token:

let first_time_login = true;

eva.on(EventKind.LoginFailed, (err) => {
  if (err.code === EvaErrorKind.ACCESS_DENIED) {
    // show login window
    if (first_time_login) {
      first_time_login = false;
    } else {
      // display err.message
  } else {
    // handle server error

The same method is used when client can authenticate itself with basic authentication on front-end sever and in mobile clients.

Secondary pages

By default, the interface should be programmed in a single HTML/J2 document ui/index.html or ui/index.j2, however sometimes it’s useful to split parts of the interface to different html page files.

Each HTML document should initialize/login the engine to access its functions. However if eva_sfa_set_auth_cookies is set to true, the secondary page can log in user with the existing token:

eva.on(EventKind.LoginFailed, (err) => {
    // token is invalid or expired, redirect the user to the main page
    document.location = "/ui/";

Authentication with front-end server

If there is a front-end server installed in front of UI and it has got HTTP basic authentication set up, the fields eva.login and eva.password can be empty and let the engine log in using the basic authentication credentials.