I think the #ActivityPub client-to-server API is extremely important and underrated.
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@steve I think
we need to emphasize that timelines can be built from regular collections, even unordered ones, by using some intermediate representations specific to the type of timeline that a client wants to render.The fact that the specification does not directly support a mapping between a collection and a responsive timeline, *DOES NOT MEAN* one can't be built from it, only that it requires a little more effort on the client side.
My goto example is how rich mail clients allow responsive mailbox representations on top of a much less expressive collection method that IMAP provides compared to ActivityPub.
@mariusor @smallcircles @evan I’m not sure I completely follow. A timeline is ordered by time. I agree that an unordered collection could be sorted by time to create a timeline. The AP OrderedCollection “stream” is a kind of rigid presorting that anticipates what an AP client would want. However, I also agree that even those could be reordered (by time or otherwise) and/or filtered in the client to provide custom views of the activity stream.
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@mariusor @smallcircles @evan I’m not sure I completely follow. A timeline is ordered by time. I agree that an unordered collection could be sorted by time to create a timeline. The AP OrderedCollection “stream” is a kind of rigid presorting that anticipates what an AP client would want. However, I also agree that even those could be reordered (by time or otherwise) and/or filtered in the client to provide custom views of the activity stream.
@steve yes, that's how I meant it. A client fetches as much of the collection as it can, then applies whatever rules it wants to transform the result into a "timeline" when the user asks for it.
This however most likely requires local caching of the collection to have decent latency.
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@steve yes, that's how I meant it. A client fetches as much of the collection as it can, then applies whatever rules it wants to transform the result into a "timeline" when the user asks for it.
This however most likely requires local caching of the collection to have decent latency.
@mariusor @smallcircles @evan Yes, it can be done in the client or the server, or both. I’d like to see an interoperable way to define custom timelines (a kind of user-defined timeline algo) that the server maintains. A Mastodon account list timeline is a super simple version of it, but AP could provide something much more powerful (advanced filtering, merging, ranking, …). Ideally, these could be shared and customized further on the client side.
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@mariusor @smallcircles @evan Yes, it can be done in the client or the server, or both. I’d like to see an interoperable way to define custom timelines (a kind of user-defined timeline algo) that the server maintains. A Mastodon account list timeline is a super simple version of it, but AP could provide something much more powerful (advanced filtering, merging, ranking, …). Ideally, these could be shared and customized further on the client side.
@steve frankly I disagree with this point. Servers should be simple. We need to move away from the paradigm of custom purpose ActivityPub servers that Mastodon pushed where the client and server are the same service.
Timelines should be orthogonal to the ActivityPub specification and, in my opinion, kept well away from it.
What's the benefit for my client application to know what your server's preferred timeline representation is?
Let's not go down the path where everything looks like a nail because we really like hammers.
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@steve frankly I disagree with this point. Servers should be simple. We need to move away from the paradigm of custom purpose ActivityPub servers that Mastodon pushed where the client and server are the same service.
Timelines should be orthogonal to the ActivityPub specification and, in my opinion, kept well away from it.
What's the benefit for my client application to know what your server's preferred timeline representation is?
Let's not go down the path where everything looks like a nail because we really like hammers.
@mariusor @smallcircles @evan I think you read something other than what I wrote. 😀. I’m describing *user-defined* timelines where the heavy lifting is done in a server. That server would be (or could be) *general purpose* and not specific to an activity domain. I definitely wasn’t suggesting a monolithic, tightly-coupled client/server architecture. I want my timeline definitions to be portable and interoperable.
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@mariusor @smallcircles @evan I think you read something other than what I wrote. 😀. I’m describing *user-defined* timelines where the heavy lifting is done in a server. That server would be (or could be) *general purpose* and not specific to an activity domain. I definitely wasn’t suggesting a monolithic, tightly-coupled client/server architecture. I want my timeline definitions to be portable and interoperable.
@steve apologies, I take "server" in the context of ActivityPub discussion to be an "ActivityPub server", not all the other web-servers involved in the process.
And when I say "client", I mean a "consumer of ActivityPub", which as you say, many times is also a web server.
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@steve apologies, I take "server" in the context of ActivityPub discussion to be an "ActivityPub server", not all the other web-servers involved in the process.
And when I say "client", I mean a "consumer of ActivityPub", which as you say, many times is also a web server.
> And when I say "client", I mean a "consumer of ActivityPub", which as you say, many times is also a web server.
Indeed. Another term that I see people use in different meaning, also when talking about C2S.
In one meaning the user device is referred to, that you might need to hole-punch with to have a full AP server, or which depends on a server relay.
And the other meaning as role. As in client/server roles, pure conceptual, and which might swap too.
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> And when I say "client", I mean a "consumer of ActivityPub", which as you say, many times is also a web server.
Indeed. Another term that I see people use in different meaning, also when talking about C2S.
In one meaning the user device is referred to, that you might need to hole-punch with to have a full AP server, or which depends on a server relay.
And the other meaning as role. As in client/server roles, pure conceptual, and which might swap too.
@smallcircles @mariusor @evan C2S is described (too loosely, but…) in the ActivityPub spec. There is a client and server aspect to C2S. A C2S client is software that uses that protocol/API to interact with an ActivityPub C2S-capable server (general or domain-specific). When I refer to an ActivityPub Client, I mean software using C2S rather than consumers of ActivityPub-related data in general.
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@smallcircles @evan An AS2 Collection cannot be a timeline (in general). It’s not even ordered. An AS2 OrderedCollection (a subtype of Collection) might be ordered by time or not, so it’s also not a timeline (in general). When they are ordered by some time value (unspecified in AP) they are often called “streams” in the spec. The Mastodon content timelines are not the same as AP activity streams although a filtered AP stream can be transformed to a content timeline.
@steve @smallcircles The `inbox` and `outbox` are both sequences ordered by time. I think that should meet your requirements for a 'timeline'?
I think it's fair to call the outbox the actor's 'feed'? It is a feed of all their activities.
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@steve @smallcircles The `inbox` and `outbox` are both sequences ordered by time. I think that should meet your requirements for a 'timeline'?
I think it's fair to call the outbox the actor's 'feed'? It is a feed of all their activities.
@steve @smallcircles I also agree that activities are more primary than content objects like notes and images in ActivityPub. That is by design and reflected in the name of the data format, API and federation protocol.
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@steve @smallcircles I also agree that activities are more primary than content objects like notes and images in ActivityPub. That is by design and reflected in the name of the data format, API and federation protocol.
> I think it's fair to call the outbox the actor's 'feed'?
The actor's event bus in a pure event based approach. 😃
Does that break AP? Current fediverse?
Can AP be considered an event-driven architecture of sorts (or restrained as such in a solution design)?I really like the Motivating use cases section of the AS specs, and the primer that sits on the W3C wiki to that. Those might be further formalized so they are applied consistently.
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@steve @smallcircles I also agree that activities are more primary than content objects like notes and images in ActivityPub. That is by design and reflected in the name of the data format, API and federation protocol.
That said, I think it would be great to have reverse chronological ordered collections of objects created by the actor.
It would be nice to use `streams` like `endpoints`, as an object, and define properties like `notes`, `images`, `places` and so on off of it.
Unfortunately the loose definition and lack of examples for `streams` makes it hard to use. It's probably better just to define them as top-level properties of the actor.
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@smallcircles @mariusor @evan C2S is described (too loosely, but…) in the ActivityPub spec. There is a client and server aspect to C2S. A C2S client is software that uses that protocol/API to interact with an ActivityPub C2S-capable server (general or domain-specific). When I refer to an ActivityPub Client, I mean software using C2S rather than consumers of ActivityPub-related data in general.
@steve out of curiousity why do you make a difference between a consumer of AcitvityPub (assumedly you mean something that fetches ActivityPub using HTTP GET) and a C2S client?
My assumption is that if something fetches ActivityPub objects and is capable of rendering it to another representation for its users, that's a client to server client.
Client to server has two sections: consumer and producer and I think anything that fulfills any of those can be called a C2S client...
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That said, I think it would be great to have reverse chronological ordered collections of objects created by the actor.
It would be nice to use `streams` like `endpoints`, as an object, and define properties like `notes`, `images`, `places` and so on off of it.
Unfortunately the loose definition and lack of examples for `streams` makes it hard to use. It's probably better just to define them as top-level properties of the actor.
@steve @smallcircles I also agree that having a separate "home timeline" and "notifications timeline" makes sense. There's an open user story for that:
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@steve @smallcircles I also agree that having a separate "home timeline" and "notifications timeline" makes sense. There's an open user story for that:
The way I see it, this has the wrong stakeholder name of "ActivityPub API client developer" i.e. spec implementer, and a Home Feed is something I may want as a "Solution developer" stakeholder. In other words that library or SDK that offers me the Social API should allow me to model that.
The user story was also brought up by Mastodon, a Microblogging solution built on top of AP (ideally).
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> I think it's fair to call the outbox the actor's 'feed'?
The actor's event bus in a pure event based approach. 😃
Does that break AP? Current fediverse?
Can AP be considered an event-driven architecture of sorts (or restrained as such in a solution design)?I really like the Motivating use cases section of the AS specs, and the primer that sits on the W3C wiki to that. Those might be further formalized so they are applied consistently.
@smallcircles @steve I know what an "event bus" is but I don't think it applies here. Usually it means a global data structure that attached processes can add events to and read events from. We don't have that in ActivityPub.
I think it's fair to say that activities are like events.
I also like the use cases and primer.
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The way I see it, this has the wrong stakeholder name of "ActivityPub API client developer" i.e. spec implementer, and a Home Feed is something I may want as a "Solution developer" stakeholder. In other words that library or SDK that offers me the Social API should allow me to model that.
The user story was also brought up by Mastodon, a Microblogging solution built on top of AP (ideally).
@smallcircles @steve please comment on the issue!
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@steve out of curiousity why do you make a difference between a consumer of AcitvityPub (assumedly you mean something that fetches ActivityPub using HTTP GET) and a C2S client?
My assumption is that if something fetches ActivityPub objects and is capable of rendering it to another representation for its users, that's a client to server client.
Client to server has two sections: consumer and producer and I think anything that fulfills any of those can be called a C2S client...
@mariusor @smallcircles @evan C2S has client-side and server-side aspects (different, but overlapping, behavioral requirements, etc.). Both sides consume *and* produce AP data (pull and push for S2S, currently only pull for C2S). Fetching AP data (URI dereferencing) is common to both C2S and S2S.
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@mariusor @smallcircles @evan C2S has client-side and server-side aspects (different, but overlapping, behavioral requirements, etc.). Both sides consume *and* produce AP data (pull and push for S2S, currently only pull for C2S). Fetching AP data (URI dereferencing) is common to both C2S and S2S.
@steve yes, but something dumb that only fetches a URL and converts the resulting ActivityPub into a valid other type of representation is a valid client in my opinion. That's what I mean, was that unclear?
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@mariusor @smallcircles @evan C2S has client-side and server-side aspects (different, but overlapping, behavioral requirements, etc.). Both sides consume *and* produce AP data (pull and push for S2S, currently only pull for C2S). Fetching AP data (URI dereferencing) is common to both C2S and S2S.
@steve @mariusor @smallcircles @evan this is a huge thread, but off-cuff comment: C2S will need a "proxy" where you can fetch a remote object **with** identity/authentication
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Some implementations skip some of these steps, because they are focused only on processing messages as they arrive. So, I am reluctant to overemphasize the message processing at the expense of the personal datastore functionality.
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@smallcircles @cwebber @steve I'm fine with that.
However, I think ActivityPub builds up persistent state on the server side which can be read and used by other processors.
For example, when I `Like` something, it goes into my `liked` collection, and the activity goes into the `likes` for that object. The `Like` activity goes into my `outbox` and others' `inbox`. People can review that information and use it.
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@smallcircles what do you have in mind, and how is the Fediverse trending in the wrong direction for it?
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Thank you, that is nice to hear. I am however not an expert, am but a humble generalist and a person who'd love to be in that Solution developer stakeholder role. Who however does not see the fediverse trend in a direction where I'd adopt the technology for what I have in mind. Drifting away from "the promise" that I read in the #ActivityPub specs in 2017, and which at the time made me decide to lend a helping hand here and there as #SocialHub facilitator and tech advocate.
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@smallcircles @cwebber @steve I would personally really appreciate that. I also think it'd be helpful for the ecosystem. I like that you combine a high-level social and technical approach to discussions of ActivityPub and the Social Web with an almost encyclopedic knowledge of the details. It's a rare combination and extremely valuable.
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@smallcircles @cwebber @steve awesome.
So, would you like me to review your diagram and give comments? I don't know what you're looking for from me in this conversation.
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So why don't you use the word REST? I never encountered "read-write API". It is an informal term.
But that is not the point. You can have a REST API, fine. But that says nothing in itself. What does it expose? You might say "Duh.. ActivityPub!" but that is not very informative either. There is the notion of message exchange, and of an addressing mechanism, indicating higher level abstractions that conform to well-known architecture patterns, and would allow us to have more productive communication, delve less in implementation details and confusions of protocol behavior with solution design functionality, for starters.
