What server-based notification support is required?

[acoburn]

Section 3.4 of the Solid specification states that a client MUST conform to the LDN specification. Are there any server-specific requirements for notifications? For example: WebSockets, which involves both client and server. And is server-to-server notification support within the scope of the Solid specification?

[RubenVerborgh]

Note that these sentences are marked as drafts; their sole purpose is to create an entry in the References section. The statement in itself is not necessarily meaningful yet.

I indeed expect there to be server requirements for some types of notifications (so the main heading needs an update), but not specially for LDN (which is already covered by LDP).

[dmitrizagidulin]

Related issues:

• solid/70 - notifications api
• solid-spec/11 - PubSub
• solid-spec/53 - semantic pingback/webmention
• solid-spec/46 - Live Updates and Push

[csarven]

Noting here that LDN is also used in ActivityPub's server-to-server interactions: https://www.w3.org/TR/activitypub/#server-to-server-interactions . Besides an AP server having some similarities to an LDP server ie. counting as potential implementation experiences, I'm not aware of Solid/LDP-based implementations with server-server notifications.

Related: more documentation on how LDN may be interoperably combined with other specs: https://csarven.ca/linked-research-decentralised-web#interoperability-across-specifications

I think server-server notifications is within the scope of Solid. There is some unofficial agreement - through conversations, e.g., involving #36 - that it should be part of Solid.

With the exception of attending issues on WebSockets in this repo, I would suggest to factor in developments from the Solid Notifications Panel: https://github.com/solid/notifications-panel - starting with use cases and class of activities, as well as having rough implementations for some guidance.

[justinwb]

Just want to raise here that I think a publish/subscribe mechanism is essential. @csarven would love to find a bit of time to discuss this.