Reminds me of the Semantic Web. I lack the knowledge to picture how that works. Do you have pointers to examples how business logic is modeled this way?
I am interested myself in following a method for solution design that starts with non-technical domain analysis and then gradually elaborates this towards implementation into an event-based architecture that is modular and easily extensible.
Just for the sake of example (and because DDG found the image) the domain analysis for an eCommerce app might be elaborated into this diagram and serve as input for implementation:
(Note: This diagram is still only very basic, more like the MVP of a eCommerce app. In real-world eCommerce there’ll be numerous edge cases, separate flows, external services invoked, etc.)
What is nice in this approach is that it translates one-to-one to code structures, while it is still non-technical and can be understood by the domain expert.
The orange sticky notes are domain events. If we want to federate parts of this model then the domain events where federation takes place are candidates to be mapped to AP activity types to be transferred over the wire, and yellow sticky notes are entities to be mapped to AP objects. Resulting in formats defined in either a custom AP vocabulary and/or reusing concepts from existing vocabs.
The business logic here is in the implementation of the “aggregate root” entities, the yellow sticky notes. Note that a domain driven design elaborated into a “CRUD of Objects” ActivityPub message exchange on the wire would have similarities to an anemic domain model anti-pattern. Exchange of semantically meaningful activities helps to convey how the domain works and follows ubiquitous language to be universally adopted.
Suppose a requirement is broad interoperability with other federated apps, and strive to offer integration points wherever we find common building blocks. Orders, offers, addresses, inventory, payment, etc. are likely candidates to consider.
This is the development approach where I’d like to find practical ways to map into AP implementations.