[JMAP] Re: Feedback on draft-ietf-jmap-filenode-01

[Bron Gondwana <[e-mail]>]

On Mon, Oct 6, 2025, at 23:34, Neil Jenkins wrote:
> On Sat, 4 Oct 2025, at 01:16, Mauro De Gennaro wrote:
>> - Sharable data types and isSubscribed: According to RFC 9670, a JMAP sharable data type MUST define the myRights, shareWith, and isSubscribed properties. However, I’m not sure isSubscribed makes much sense in the context of file storage. I’d like to hear your thoughts (and Neil’s too) on this.
> 
> I think it probably still makes sense — as the shared spec says, `myRights`/`shareWith` is whether you have permission to see it, `isSubscribed` is whether you want to see it! (i.e., The former is controlled by the person sharing the latter by the person it is shared with.) What's interesting here is the hierarchical nature of it — if you share a folder, you implicitly get permission to everything underneath it. I think the `isSubscribed` mostly only makes sense on whatever the top-level item shared with you is, or at least it doesn't make much sense to set `isSubscribed` to `false` in a folder that has an ancestor with it set to `true`. On the other hand, this is probably not going to hurt either, so possibly not worth worrying about and we can keep it consistent with the other JMAP APIs.

This works for me.  I see I'm going to have to make the sharing semantics a lot more clear.  I think this reads as:

Parent ACLs are always inherited (you can't take away something that the parent gives - if parent says canRead then all its children are readable).

The way I implemented this in Fastmail's filestorage is that you are implicitly allowed to know about any node for which you can see one of its children.  So the path to a node which you have an ACL on is visible.

This is a less powerful ACL system than some filesystems out there.  A more flexible system is "you implicitly have the rights of the parent node IFF there is no explicit ACL for you on this node".

I also didn't support setting ACLs on individual files. ACLs are only on directories.

Bron.

--
  Bron Gondwana, CEO, Fastmail Pty Ltd / Fastmail US LLC
  [e-mail]