Generation of Geofence ID (from Josh Soref)

[gmandyam]

Section 6.2

Set the geofence ID of the geofence to a newly generated value.

If you actually want this value to be something special, then newly generated value needs to link to some constraints.

[mkruisselbrink]

I'm a bit on the edge if this is something that needs to be specified more. On one hand implementations are quite likely to use UUIDs for this, but I don't see much benefit in requiring that.

Also I'm not sure if the non-unique name + auto generated unique ID way we've chosen for this API is really the best way to go. Other APIs (notifications API, background sync API, maybe more) instead have opted for a unqiue, user supplied tag (where trying to register with an already used tag will overwrite that registration). It might make sense for consistency to do the same here.

[npdoty]

The definition of the ID earlier in the spec provides requirements regarding uniqueness.

This ID is generated by the user agent and MUST be unique among all geofences associated with all service worker registrations at the same origin.

For privacy reasons, we are typically suspicious of IDs that might be shared across origins, but I believe that isn't an issue here, because access to the service worker is already limited to an origin.

[npdoty]

Should we note that these ID strings shouldn't include information about the user or be used for tracking? For example, don't include the user's name, don't just have a number increasing across origins, etc.