Can Updates-Via is also sent on 404 and can listen for creation

[timbl]

In the bit about live update,

https://github.com/solid/solid-spec/blob/master/api-websockets.md

we need to specify that you can subscribe to changes in a resource which currently does not exist, and get a ping when it is created (and thereafter to any changes).

The headers Update-via and `MS-Author-Via: are sent on 404 as well as 200.

NSS sends the headers now. i haven't tested the actual WS ping message on file creation.

See also

linkeddata/rdflib.js#392 in rdflib

which is depended on by

https://github.com/solid/solid-ui/issues/228 a issue with the chat UI needing this.

[melvincarvalho]

@timbl Why not all 4xx?

Alice wants to access Bob's class notes, but gets a 403. She clicks a button to send an access request to Bob's inbox. Bob's inbox bot recognizes Alice as a close friend and updates permissions. Now Alice can view the notes.

Same use case as above with a 402 for a paywall etc.

[csarven]

Is this issue duplicated by https://github.com/solid/solid-spec/issues/217 ? Note that I've transferred 217 to https://github.com/solid/specification/issues/166 so that it can be addressed by the ongoing work in solid/specification. Note: https://github.com/solid/specification/issues/166#issuecomment-617654827