[Webpush] Use Case related to subscription sets

[Hervé Ruellan <[e-mail]>]

Hi all,

We, at Canon, have a use case that is dependent on the rules relating 
subscriptions and subscription sets.

In this use case, a device (e.g. a camera) connects to a push-server 
through a proxy (e.g. a mobile phone). The communication between the 
camera and the proxy uses an appropriate protocol (most possibly not 
HTTP). A notification goes from the push-server to the proxy (acting as 
a user-agent) through WebPush, then from the proxy to the device through 
the appropriate protocol.

We plan to use the same proxy for several devices. We would like to 
allow a device to change from a proxy to another seamlessly (e.g. going 
from the mobile phone to a PC when coming home). When a device moves 
from a proxy to another, we would like it to keep the same subscription. 
This means that each device would need to have its own subscription set 
to contain its subscription (or subscriptions).

Supporting this use case means that a client, here the proxy, is allowed 
to have several subscription sets. However, this number would be quite 
limited as we think only a few devices would connect through the same proxy.

This scenario is of importance for us, and we would like the WG to take 
it into account in the definition of subscription sets.

Cheers,

Hervé Ruellan