Comment by carlsverre
2 days ago
Glad you enjoyed Graft! The system your describing sounds very cool! It's actually quite similar to SQLSync. The best description of how SQLSync represents and replays intentions (SQLSync calls them mutations) is this talk I did at WasmCon 2023: https://www.youtube.com/watch?v=oLYda9jmNpk
Cool! That's an interesting approach putting the actions in wasm. I'm going for something more tightly integrated into an application rather than entirely in the database layer.
The actions in my prototype are just TS functions (actually Effects https://effect.website/ but same idea) that can arbitrarily read and write to the client local database. This does put some restrictions on the app -- it has to define all mutations inside of actions and capture any non-deterministic things other than database access (random number, time, network calls, etc) as part of the arguments. Beyond that what an app does inside of the actions can be entirely arbitrary.
I think that hits the sweet spot between flexibility, simplicity, and consistency. The action functions can always handle divergence in whatever way makes sense for the application. Clients will always converge to the same semantically valid state because state is always advanced by business logic, not patches.
Patches are recorded but only for application to the server's database state and for checking divergence from expected results when replaying incoming actions on a client. It should create very little load on the backend server because it does not need to execute action functions, it can just apply patches with the confidence that the clients have resolved any conflicts in a way that makes the most sense.
It's fun and interesting stuff to work on! I'll have to take a closer look at SQLSync for some inspiration.
Woah that's awesome. Using Effect to represent mutations is brilliant!
Any chance your project is public? I'd love to dig into the details. Alternatively would you be willing to nerd out on this over a call sometime? You can reach me at hello [at] orbitinghail [dotdev]
As promised, here's the code. I decided to call it Synchrotron. Not ready for use yet but there is design/planning in the readme and a suite of passing tests showing that the approach can work. https://github.com/evelant/synchrotron
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I haven't put it up in a github repo yet, it's not finished enough, but I will after spending a little more time hacking on it. I'll try to remember to come back here to comment when I do =)
Using effect really doesn't introduce anything special -- plain async typescript functions would work fine too. My approach is certainly a lot less sophisticated than yours with Graft or SQLSync! I just like using Effect. It makes working with typescript a lot more pleasant.