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Levels (javax.faces.WINDOW_ID_MODE)

• none
• url
• clientcustom

none-Mode

By default Window-Id's are deactivated to ensure backward compatibility.

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That's a very simple approach which has some disadvantages. It just adds the Window-ID to all URLs. That works if users don't open e.g. a link in a new tab (it would clone a window - that isn't nice but not worse than the HTTP session itself).

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Furthermore, a "drop" script detects the "open in new tab" use-case and drops the current window-id and requests the page again with a new window-id.

custom-Mode

This mode will also add a small JS impl to the page to fix the restrictions of the 'url-Mode' (esp. via dropping the old Window-Id if users open e.g. a link in a new tab).
If a HTML5 browser gets detected, HTML5 features will be used by the JS implementation.allows that a JSF implementation or RenderKit provides a proprietary mode which is even more optimized - e.g. using an intermediate page which can be stored in the local-storage of HTML5.
Values: custom:name of the mode e.g.: <param-value>custom:intermediate-page</param-value>

Open Topics

Also is it better to have new window-ids per request, if no js is available, or one window-id for all windows?

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