I'm still not clear about the discussion we had yesterday.

Steve Bate

@evan I understand. That's why I said repeatedly that I'm not discussing serialization. I agree that serializing Collections with embedded copies of Objects is needed for interoperability with most existing AP S2S implementations. To clarify, are you concerned about statements related to valid, allowed AP (serialized) representations that aren't the ones typically implemented? Versus invalid representations?

Evan Prodromou

@steve so, this is an interesting question. I'd say, as an interoperability standard, AP doesn't make any (well, not many...) assumptions about underlying models. The JSON-LD serialization is all you get; each implementation decides how to manage its own structures internally.

Evan Prodromou

@steve and, yes, what I worry about is when people say, "the value of the `object` property can only be in its JSON object representation" or "the members of the `items` array can only be URLs". It's not true, it's hard for people to understand, and it drives us towards fragile implementations.

Steve Bate

@evan We're back in the circular reasoning since JSON-LD *has* a well-defined data model. It's RDF and graph-based (Chapt 10. JSON-LD 1.1 spec.). The statement that AP uses "JSON-LD" but is not an RDF data model doesn't make sense to me given how JSON-LD is specified. I don't think JSON-LD provides much extensibility benefit to plain JSON apps. Maybe there should be a variant of #ActivityPub that is unambiguously plain JSON with a plain JSON extensibility design? Maybe less confusing for devs?

Steve Bate

@evan Some AP advocates/activities like @smallcircles have been proposing something similar to this for a while now (discussed on SocialHub).

Evan Prodromou

@steve so, it sounds like you want to believe in some kind of secret, hermeneutical ActivityPub that one can only understand if you cast enough RDF spells.

But there is no such secret formula. We made no pact with the RDF powers when we started using JSON-LD for AS2.

Evan Prodromou

@steve @smallcircles lol

Evan Prodromou

@steve We created these types and structures to represent activities, actors and objects on social networks. An object with type Person represents a person. An object with type Video represents a video. An object with type Collection is a collection.

The RDF model is no more significant than the curly brackets and colons in the JSON.

Evan Prodromou

@steve no.

Steve Bate

@evan There's no need to "cast" me in that light. However, intentional pact or not... it would be like selecting RDF/XML as the AP/AS2 representation but saying it should be treated as generic XML and has no relationship to RDF. Or using Turtle and suggesting that it be interpreted as just lines of text with no relation to RDF. I think it's a very confusing position. If you had to make that decision (to use JSON-LD) today, would you make the same decision? Why?

Evan Prodromou

@steve also, I wonder if you've read the section on object representations in Chapter 2 of my book? It goes into a lot of detail about how these things interact.

ActivityPub

ActivityPub is the new standard for connecting social networks together on the social web. This open, decentralized social networking protocol defines an API for sharing activities to a social network … - Selection from ActivityPub [Book]

O’Reilly Online Learning (www.oreilly.com)

Evan Prodromou

@steve I think James had switched to JSON-LD before we started the WG. We discussed it a lot; the continuum between JSON, JSON-LD, and RDF. I think the balance works well, and I like how much the RDF community has embraced AS2. There are a couple of other schema languages for JSON, like JSON Schema, but I don't think they lend a lot that JSON-LD lacks.

Erin 💽✨

@evan @steve I remember AS2 as JLD being part of the WG charter, and therefore not really up for discussion. Maybe that discussion was had before the invites went out, but it felt too me a bit like a mandate from "on high" (i.e. the W3C)

I regret how the JLD interop was specified in the spec though. I think we could have done better

Evan Prodromou

@steve oh, and the example you gave about XML is exactly how people worked with RSS up until version 2.0!

Evan Prodromou

@erincandescent @steve James used JSON-LD in the later drafts of the AS2 RFC, so it antedated coming to W3C. But it definitely also worked as a selling point internally, at least until the SoLiD schism.

Steve Bate

@evan JSON-LD is a Linked Data (RDF) serialization. I think it's a stretch to call it a schema language in the same genre as JSON Schema. The JSON-LD AP context can only be compared to a schema language in very limited ways. I'd expect one would use RDF Schema (RDFS) or SHACLE or Shape Expressions (ShEx), maybe OWL, *with* JSON-LD for that purpose. Given that, would you personally still choose JSON-LD today, since the focus is on plain JSON? I'm not asking about what Snell chose a decade ago.

Steve Bate

@evan I'm not exactly clear about the analogy, but maybe someday we'll say that's how it worked in ActivityPub up until version 2.0!

Evan Prodromou

@steve early versions of RSS were based on RDF/XML. Version 2.0 is not. People parsed it as plain XML.

Evan Prodromou

@steve also, you don't have to wait for some imaginary future version. If you want to change ActivityPub, make extensions. It's really easy, and if your extension gets popular, it will get merged into the main AS2 context.

Evan Prodromou

@steve it's no longer up to you or me. The AS2 spec was standardized in 2018 and AP in 2019. We have hundreds of implementations, tens of thousands of servers, and tens of millions of user accounts.