@raphaelRaphael Lullis Nevermind, side effects wouldn't be a problem. However, it still doesn't seem to be compatible with ActivityPub... Because Announce activity is not defined in C2S context :)
https://www.w3.org/TR/activitypub/#client-to-server-interactions
@silverpill @raphaelRaphael Lullis 
@julian 
@mariusormarius
In my book if a side effect is part of the protocol specification, then it constitutes a protocol capability. If not, then it is part of some app's / solution's business logic.
The definition of "ActivityPub extension" by itself is unclear. With overloaded use causing confusion. It may refer to:
- Protocol extension
- App / solution built on top of the protocol
To deal with protocol capabilities they must have water-tight specs, well-defined behavior and strict consistent use across the fediverse.
To deal with side effects that are part of solution designs for a particular application or business domain things go from simple to very complex in the amount of introspection and machine-readability that the #ActivityPub Actor abstraction offers.
Simplest is finding the URL where the docs of the extension / solution design sit. Most complex is full introspection and handshaking. The latter is the Solid route.
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