SESSION DEVICE-ID Attribute¶

DEVICE-ID is a custom attribute to the 4GL handle SESSION. It's specific to the FWD framework and offers a read-only access to the unique identificator of the end-user device.

Attribute Type: CHARACTER.

The value is never expected to be unknown (?).

In desktop clients (GUI / ChUI) the device id is the unique id provided by the operating system on the client machine. In Unix it's in the format 7f5c9c64b34d4055b746f68bd86a4b8a, found by the cmd head /etc/machine-id. In Windows it's in the format 16B1FCB5-2726-701A-A89A-A7BBC18F009D, found by the cmd wmic csproduct get UUID.

In web clients (Virtual Desktop and Embedded) the device id is a unique id generated by the server and digitally signed by the server private key using the SHA256withRSA algorithm and returned to the browser as the secure, HTTPOnly cookie FWD-Device-ID. It's attached on opening the login page or during the authentication request (GET or POST /login), when the cookie doesn't exist.

The implementation in FWD doesn't promise persistent, constant value for the same device, because the cookie can be deleted in the browser and a new device id will be generated. But this doesn't prevent the device id being used to enforce the one browser policy (enabled by webClient/oneBrowserPolicy configuration), where multiple browsers are disallowed to simultaneously run web clients. The one browser feature collects references to the sessions that are (or pretend to be) running in the same browser and confirms the validity of this condition in the browser itself, before running a new client process.

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