[aboodman]

I’m not sure if you are understanding that when Replicache rebases operations locally it actually re-executes code which can have arbitrary effects. This design yields a lot of flexibility to preserve intent: the function can look at current state of world and decide to do something different.

Now, it is true that OT is considered the gold standard for certain kinds of collaborative editing, in particular unstructured text. But CRDTs are quickly catching up and I believe that any CRDT should by definition be implementable on top of Replicache.

Its also quite a lot easier to implement a Replicache backend than an ot backend.

[josephg]

I don’t know enough to comment on replicache, but you can also do OT on top of an operation based CRDT. For diamond types we’re making it support both - so if you want to, applications can do OT (which is simple, small, and fast) to talk to a server (or local proxy process), and then that process can do p2p server to server replication using CRDTs.

The result is we need way less complexity in the browser, or in applications. And still get all the advantages crdts bring - namely, no need for a central server acting as the source of truth.

[aboodman]

Cool, I need to look into this more.

I think for many customers the authoritative server is an advantage. It's useful in SaaS apps for the server to be able to override the clients, for all kinds of reasons -- antiabuse, authorization, extra validation rules, or just fixing bugs.

[josephg]

Yes, I completely agree. And I think we want both:

- A fast and well written CRDT that works in p2p networks should also work great for server-to-server replication in a data center (or across data centers).

- OT algorithms designed to work with centralized servers are simple, efficient, easy to code up and easy to work with. And they provide a really nice API for local applications to do IPC. CRDT libraries can expose OT endpoints just fine.

I'm still not 100% sure about what the best approach is in the P2P case. Embedding (/ linking) a CRDT library into every application would also work fine, but its complicated to get everything working across languages. And harder to update. The other option is running a single system / applicatoin wide CRDT-like service which manages credentials, that applications talk to like LSP / D-Bus. In that case, applications can just talk OT (which is much simpler).

Either approach would work.