Thanks for the questions!
Maybe a first quick clarification on the architecture behind the demo. There are two parts to it:
- A Web client: GeoPub
- An ActivityPub-esque backend: CPub
Both are necessary to support “arbitrary” content (e.g. events, descriptions of local organizations, etc.).
Short answer:They can set up their own.
The software need to run an instance is CPub - the backend. CPub is very much designed to be self-hostable (even on very small hardware). Individual users will be able setup their own instance and participate in the federated network. In practice I expect that most people will use an instance setup by a local organization. Very much how the Fediverse works now.
Maybe slightly different than the Fediverse, we are trying to make the backends as simple/stupid as possible. For example:
- Querying data is done on client-side
- Content-addressing so that backend is not required for assigning identifiers
- Client side verification of content authenticity
We hope this will allow us to build more “offline-first” clients, reduce complexity and reliance of backend and in general move more toward a more decentralized system.
The plan is to federate using the ActivityPub protocol.
All the things mentioned above seem to be mostly compatible with the ActivityPub protocol. Or at least that is the hope.
I imagine there to be many different applications with UIs specialized for specific data types. A bit like how Solid is supposed to work (we also intend to implement the Linked Data Platform specification - so Solid apps will also be usable clients).
There is already one specialized client that interacts with CPub (unfortunately not Free Software or open-source) - an application developed by a local Tourism Agency that allows users to comment on news entries, hiking trails and events. The comments are just ActivityPub notes that can also be seen from GeoPub (or in the future any other ActivityPub client).
CPub almost supports the ActivityPub Server-to-Client protocol, so any ActivityPub client should be usable. We are also thinking of implementing the Mastodon API as most clients seem to use that instead of the ActivityPub Server-to-Client protocol.
GeoPub is an experiment into how arbitrary data (RDF) can be interacted with. Unfortunately I do not know how to make nice or appealing UIs…