Add a Tag type

[cwebber]

We resolved on the Community Group call today to add a Tag type to the ActivityPub spec. Multiple implementers found it frustrating that there's a specific object type for Mentions, but not for everyday text-style tags.

[nightpool]

Question about details—is this something we need to do with ActivityStreams? Or can we just say that ActivityPub extends ActivityStreams in this way?

My understanding is that so far we don't extend AS2 anywhere—AP says "ActivityPub uses [ActivityStreams] for its vocabulary". Are we comfortable with this change? What are the other options?

As far as the standardization process goes, what's the best move here?

[cwebber]

ActivityPub already extends ActivityStreams. The inbox and outbox are terms not in AS2 itself. Per past resolutions of the group we have permission to do this. (Good question though!)

[cwebber]

We're going to wait on James Snell's comments on this to hear why it wasn't in AS2. Also Evan and AJ both say that if we did it, it shouldn't go in ActivityPub because it's not an AP specific extension, it should be an independent extension

[tantek]

Links to where the use-cases are documented for this?

[cwebber]

Don't have time at the second to pull up notes, but @Gargron said that Mastodon went ahead and added a Tag object.

BTW, I think we should get an answer from James on this, but I think this may fall under the "this should be an extension because it's not a requirement for the protocol to work" aspect.

[rhiaro]

What would Tag actually help with that isn't possible already? I realise I missed the discussion on this.

Off the top of my head, if you follow the as:tag relation and find an as:Object, the UI is going to want that object's name I expect, which it can get regardless of the type of that object. Anything else?

In my implementation (sloph), tags are as:Collection types, and every post tagged with them is discoverable through as:item.

Or maybe this is for tags which don't have a URI, only a string, which would be a value for name on an as:Object? (ie. blank nodes). Still, if you go from an Activity or Object through the as:tag property, and find a generic Object there, you can infer that it's a tag...

[cwebber]

Part of the rationale was that Mention has its own type, very specifically for this type of thing, but "Hashtag" type string identifiers doesn't have a type which is weird, and maybe even not helpful for people who are trying to map this to localized types clearly? But I may be forgetting; perhaps @Gargron can refresh our memories on their motivation?

[tantek]

I have the same questions (confusion?) as @rhiaro I think. But I'm also ok with a "tag-of" type parallel to "mention" (assuming that's pre-existing). For reference, indieweb posts have had this specific response for a while: https://indieweb.org/tag-of which is a type under consideration in Post Type Discovery https://www.w3.org/TR/post-type-discovery/#othertypes (Update: added tantek/post-type-discovery#28)

[Gargron]

I have added type: "Hashtag" to Mastodon because when I'm parsing the "tag" attribute and iterating over the items I'd like to know what the item is. A "Mention" type exists so there should be a "Hashtag" type as well.

[cwebber]

Proposed as an extension to the SocialCG (and we'll be talking about the process for getting things in at the SocialWG this week, and raising it on the SocialCG call).

[cwebber]

I asked @jasnell about this and got the following response:

I think at this point if they have found a solid use for it then ++

Let's make it happen!