ProviderId Clarification

[MahdiBaghbani]

Reading through the #194 and #196:

Clarification on providerId semantics

The text says:

This is unique per provider.
If the same resource is shared twice, this providerId will not be repeated.

Read together, they're ambiguous. Two possible interpretations:

Resource scoped: providerId identifies a resource within the provider. If the same resource is shared multiple times, the same providerId should appear each time

Share scoped (per receiver): providerId identifies a share instance created by the provider. If the same resource is shared to two receivers, the providerIds differ. This aligns with Nextcloud/ownCloud, where share IDs are created sequentially in the share table.

[MahdiBaghbani]

If providerId is share-scoped (unique per provider and per share instance), how should reshares behave?

Example:

P1 shares resource R to P2 
providerId = P1:1001. 

A user at P2 then reshares R to P3.

Should P2 issue a new providerId (e.g., P2:7005) for the reshare, possibly carrying P1:1001 as an origin/reference, or should P2 reuse P1:1001 to preserve continuity across the chain?

In this example suppose that P2 is acting as a proxy and proxies the WebDAV calls from P3 to P1, so P1 is oblivious to the existence of P3

[glpatcern]

The text says:

This is unique per provider.
If the same resource is shared twice, this providerId will not be repeated.

Read together, they're ambiguous. Two possible interpretations:

The extra paragraph stating this providerId will not be repeated was meant to clear any ambiguity. If some ambiguity remains, we can make it even more explicit that the providerId is share-scoped, i.e. unique per provider and per share.

For the resharing, the idea has always been that access is made to the original provider (which is expected to grant reshare access, and would be signaled with a REQUEST_RESHARE notification), to avoid to make proxy calls and slow down the actual data exchange. Therefore, in the example, P1 -> P3 would be another share with a new providerId.