@steve This is really interesting.
I see a few cases. One is an ActivityPub API façade for an existing CMS, like Drupal or WordPress. The underlying system only stores Articles, so it tries to fit any input into that format. It might also take a Create/Image and return an Article with an embedded image, say.
@steve This is really interesting.
I see a few cases. One is an ActivityPub API façade for an existing CMS, like Drupal or WordPress. The underlying system only stores Articles, so it tries to fit any input into that format. It might also take a Create/Image and return an Article with an embedded image, say.
@steve I could also see if the server is checking the content type of the payload, and changing it on the fly. For example, a Create/Image with an MP4 movie as the payload, and it changes it to a Video. In the case you're explaining, maybe the Note has many paragraphs, and the server changes it to an Article to match the expectations for that type.
@steve Finally, just an opinionated server developer -- "there's no difference, everything should be an Article."
@steve In a way, the server is the most responsible for the object long-term -- it stores and serves the data, assigns it an id, provides security, and so on. It also maintains a long-term relationship with the user, including the user's preferences.
But the client is closer to the user, in the moment, and may more accurately represent the user's immediate needs and wants.
@steve I'd say, don't do this if you don't have to.
@steve I think I’d be Quite Annoyed if a server did that when the C2S app I’m writing sent a Note. I’m asking it to Create a Note - I expect it to create a Note or fail to create a Note, not do some weird, unexpected third thing.
I could maybe tolerate it adding a second type, but while my code can handle multiple types most ActivityPub software doesn’t seem to accept that kind of thing.
@steve If you consider also peer 2 peer networking as an option, your client might switch it's role and act as a server.
In this case it having such a different inside outside mapping for objects will become confusing.
Keeping msgs immutable is a general best-practice, I gather.
In the case you mention it becomes confusing to still use client/server terminology. You have a full actor on the client's side, and when it sends a msg it acts in server/S2S role.
Btw, in that scenario we do not have to make the distinction client + server anymore, as we have just actors communicating with each other. Then we can think in terms of the actor model, and honor its qualities.
A client sending to the server's outbox is then analogous to an actor sending to another actor's inbox. That is a one-way msg exchange usually, fire and forget (esp. in a pure event-driven architecture... which the current fediverse is not). The remote actor is not responsible for keeping the Activity (event) in its server-outbox / actor.inbox. That corresponds to the spec part "may disappear at any moment".
@smallcircles @jerger > In the case you mention it becomes confusing to still use client/server terminology.
In this case, I think the terms makes sense in the specific content of #ActivityPub clients and servers. There's significant overlap in the behaviors of the two, but there are significant differences too. For example, a client cannot federate and often runs in an environment where it can't expose listening sockets (browser, behind a firewall, etc.).
@smallcircles @jerger I feel like using C2S client and S2S server is a bit more precise than "app" for this thread. At this point, I haven't been able to determine how you define "app".
Yes, I would highly discourage the use of "app". It is why I scare quoted it, but "app" is common language when people talk about the fediverse. "App" is a neat container concept that fits the full scope of ones own FOSS project, but on the fediverse - a growing heterogeneous and interoperable social network - one becomes highly dependent on the foundational network communication layer based on #ActivityPub, and any fedi FOSS developer should be concerned beyond direct project scope, and pay attention that this foundation evolves healthily. This unfortunately happens unsufficiently, and only a very small number of people try to get the ecosystem as a whole to higher levels, volunteering time where it does not directly benefit their own projects. Think @silverpill for the #FEP and @evan for #SocialCG.
Cool find yesterday was that @HolosSocial rather than C2S has a "full AP server" client-side, that communicates with a Websockets tunnel to a dedicated relay server.
@smallcircles @silverpill
@HolosSocial Holos Social is interesting, but to avoid confusion, the phone app is not a "full AP server". It can't federate without an external relay server, for example. Although it combines both client-like and server-like functionality, I don't see it as an alternative to C2S. With C2S I'd be able to access my account/actor from a phone, a tablet, and desktop and laptop computers with different clients. Holos Social binds the actor to a single phone IIUC.
lets say there is a local-server sending this create/note to a distant-server.
Whatever object distant-server creates internally I am very neutral.
But I am very engaged from
1. viewpoint of local-server I expect to get feedback about a note object & being able to deref a note object.
2. viewpoint of distant-server user I expect to see a object behaving like a note.
In a bottom line - naming a note different makes absolutely no sense at all ...
@steve why should C2S being different ?
I agree with this. The #ActivityPub spec says:
> The server MUST then add this new Activity to the outbox collection. Depending on the type of Activity, servers may then be required to carry out further side effects. (However, there is no guarantee that time the Activity may appear in the outbox. The Activity might appear after a delay or disappear at any period). These are described per individual Activity below.
My expectation as a client is that I find the Activity I just sent in the outbox on the server with the same (Note) payload. If there's translation into Article, then this is a side-effect that comes after that.
Although @steve in the exchange with @mariusor refers to a "generic client" and I wonder what that means exactly.
Specific client / generic server: The client is the "app". Server only 'serves', does not violate client's expectation. It handles the CRUD, 'caching' and addressing, has no side effects that are relevant to the client. Client is in charge, and Activity is an event (it happened, deal with it).
Generic client / specific server: The server is the "app", client not in charge. Client acts like 'front-end' for server functionality. The Activity constitutes a command to be processed. As client I'd expect it to be immutable, and that's probably best-practice too.
Specific client / specific server: Side effects on server constitutes a different "app" than on the client. Client sends an event, server processes, may trigger further server events that may address the client. I'd still expect the event to be immutable, Create/Note stays the same.
@smallcircles @jerger @mariusor I meant "generic" primarily to mean it's not a client for a specific server implementation. In this case, it is a C2S testing client so it is not specific to a particular user domain either. In the first sense of "generic", I could imagine a media publishing app (images, videos) that's not tied specifical to PixelFed or PeerTube (as examples). Or a "generic" microblogging app. The latter is where the Note to Article conversion would probably be an issue.
Guess this is a general area where due to the lack of clear protocol layering there's much confusion in overall terminology usage.
The whole idea of an "app" is not part of #ActivityPub itself. It is a leaked abstraction on what devs think they offer ("I build an app for my users").
There is no "generic" microblogging app, unless there exists an agreement for the specification of said app. PixelFed is a spec, PeerTube is another spec in different domain. A generic microblogging app would live where? As FEP? Collection of FEP's? W3C Note giving a 'specification profile'?
@steve from what point of view is this question?
What would I think as the user that sent a Create/Note? Probably would not care/know.
What do I think as a server that receives a Create/Article? Makes no difference. Would the canonical version of the saved object also be Article if I dereference it?
As a spec implementor and user, I would probably be upset that my intent was not preserved.
@mariusor Like I said, this is a C2S context. Let's say they do know. Your opinion is that the user should not care? I'm guessing there are other kinds of C2S server-side changes that you'd believe they would care about (changing content, addressing, etc.).
@mariusor And I'm thinking of a general C2S client (not one developed by the server developer for that specific server). The client developer might care for technical reasons. For example, some servers don't support Article S2S federation so the example I described (converting Note to Article in the server) could have undesired results.
@steve the problem as I see it is only with the "misrepresentation of the user's intention". Which might, or might not cover the aspect that you referred to...
@mariusor Like you said, I'm not sure the user (rather than the client dev) cares about details like the AP object type. However, they may care from a UX perspective if their messages are silently dropped (during S2S federation because the type was changed). And if they do care, they'll probably complain to the client developer who didn't cause the problem. 😉
@steve but did you actually observe this behaviour in any servers? What made you ask the question?
To me it sounds very implausible, because the server *actively* needs to do something instead of piping the received activity directly to its recipients. Is it a case of "the server doesn't render Note objects" so they silently convert to something they do?
Even that's implausible to me, because the same code can be used to render both... 
