[janesconference]

A couple of questions about y-sweet, based on the experiences I had with CRDTs:

1) Does the server keeps in memory the "active" documents? In other words, does the server need to open a document and keep it in RAM while clients are connected to it (I assume there's a websocket connection somewhere in the client that keeps it hot)? Or is the server stateless - just connects to the store when needed? I found the latter very hard to do.

2) Does the client persist entries using indexeddb? If yes, does opening many tabs cause redundant writes as they all sync with the server? If not, does the client need to fully re-sync with the server anytime it wakes up?

3) Is it possible to observe updates on the client as they come? One of the major use cases of CRDTs is to index data on the client - then you can have a dumb server that just syncs data between clients and a smart client that does search, graphs, visualizations etc. on the data it receives. To do that, the client needs to observe updates one by one and process them to create secondary indexes. Is it possible to do with y-sweet without forking its source code? I remember getting updates yn Y.js being quite inefficient as you need to replay them all or something similar, but that was a couple of years ago.

[paulgb]

Good questions!

> 1

The server keeps the documents in memory when they are open, but it is horizontally scalable by hosting using CloudFlare Durable Objects. (We also plan to support Plane.dev but that's not built out yet).

> 2

The client is based on Yjs, so it's compatible with Yjs' y-indexeddb provider to store in IndexedDB. Tabs synchronize state between each other using a local broadcast channel. The client only synchronizes unsynced state with the server, so if one tab has already pushed the local offline edits to the server, the other tabs can discover that and avoid pushing them. That said, I'm not 100% sure if Yjs deals with the race condition where two tabs wake up at the same time so the server has not yet received offline edits from either, I'd have to check on that.

>3

Yes, Yjs types have an `observe` method that takes a callback, which receives an event with details of each edit. Here’s an example for observing events of a Y.Map: https://docs.yjs.dev/api/shared-types/y.map#observing-change...

[janesconference]

Thanks! Re: 1, the docs are not really deep on that, but from your answer it seems it possible to self-host y-sweet on Cloudflare workers (I guess) with Durable Objects as storage? Also, if you guys are going to have a paid plan, how do you see the prices going? Comparable to, say, Supabase per user, less or more?