Browser, Connection and Session: How FMWeb Works Behind the Scenes
Overview
FMWeb is a Blazor Server application: the interface runs in the browser, the actual logic on the server. The two are coupled via a permanent connection (WebSocket/SignalR) – every click is reported to the server, which updates the page. This makes operation fast and saves installations, but it also means: no connection, no operation. This article explains what happens with connection problems and how the session and theme setting behave.
Connection loss and reconnection
- The connection is checked every 15 seconds via a heartbeat; if the server stays silent for longer than 2 minutes, it is considered disconnected.
- If the connection drops (Wi-Fi switch, dead spot, standby), FMWeb overlays a reconnection indicator over the page and automatically tries to restore the connection. During this time you cannot operate the page.
- If reconnection succeeds, you continue seamlessly – open pages refresh, editing locks are re-checked, and the vehicle file may offer to restore an unsaved draft (Article 44).
- The server keeps a disconnected session for up to 30 minutes. After that (or after a server restart), only reloading helps – unsaved entries outside the draft autosave are then lost. So save regularly.
The red error bar
If the red bar "Ein Fehler ist aufgetreten. Diese Anwendung reagiert möglicherweise nicht mehr, bis sie neu geladen wird." (An error has occurred. This application may no longer respond until it is reloaded.) appears at the bottom edge, the session is finally lost or an unexpected error has occurred. Click "Neu laden" (Reload) – you stay logged in and land back on the current page. If a page instead shows the message "Ein unerwarteter Fehler ist aufgetreten. Bitte Seite neu laden." (An unexpected error has occurred. Please reload the page.), use the Neu laden (Reload) button there. If the error recurs, contact support with the time and page name (Article 17).
Multiple browser tabs
You can open FMWeb in multiple tabs – the login applies to all tabs of the same browser. However, each tab maintains its own connection with its own page state; filters or unsaved entries in one tab are not visible in another. Note: if you open the same vehicle file in two tabs, the editing lock blocks the second tab (Article 44).
Login session
The login is stored in a cookie and is valid for up to 8 hours; with active use it is automatically extended. After that, FMWeb redirects to the login page (login and SSO: Article 115).
Theme setting (Light/Dark)
Your choice between the light and dark theme is stored in the cookie fmweb_theme – per browser and device, valid for one year. On loading, the server reads the cookie before the first display, so the page starts in the correct theme without a "flash". On another PC or in another browser, you set the theme once again (Article 119).
Browser recommendations
- Current version of Chrome, Edge, Firefox or Safari; older browsers without WebSocket support are unsuitable.
- Allow cookies (login and theme) and whitelist FMWeb in ad/script blockers.
- In corporate networks: the proxy/firewall must let WebSocket connections through to the FMWeb address and must not cut off long-lived connections after a short time.
- A stable network connection is more important than high bandwidth – the amounts of data transferred are small.
Frequently asked questions
On a train / over VPN, the reconnection indicator constantly appears. That is normal with unstable connections. FMWeb reconnects automatically; as long as the interruption stays under about 30 minutes, nothing is lost. With frequent drops in the corporate network, IT should check the idle timeouts of the proxy/VPN.
After opening the laptop, FMWeb no longer responds. After a long standby, the session has usually expired – reloading the page (F5) is enough.
Does closing the tab log me out? No. The login persists until the 8 hours expire. On other people's devices, always actively log out via the user menu.
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