Julia DeMille (Oct 29 2024 at 18:20): Julia DeMille (Oct 29 2024 at 18:20):Call me a mad scientist for this, if you'd like.
I want to be able to, at runtime, satisfy a component's imports, using the exports of another component I have instantiated, without having to manually define each resource and function.
This doesn't seem possible right now. I want to make it possible. I have never contributed to wasmtime, and this is certainly a huge project to take on as a first contribution. I've been looking under the hood, and have some ideas, but I figure I should probably announce my intentions so people know I'm up to this. That way, I can hopefully ask questions, too.
Chris Fallin (Oct 29 2024 at 18:27):@Julia DeMille a very interesting goal for sure!
it might help (me, anyway) to define a little more what you mean by dynamically/at runtime: do you mean that you want to start a component C, without any of its imports initially, and as external resources are called/used, dynamically fill them in somehow? or do you mean that you want a reflection-like introspection ability from within one component, to load another component, work out what it needs to instantiate, and invent/plug that in before starting it? or something else?
Julia DeMille (Oct 29 2024 at 18:29):Chris Fallin said:
or do you mean that you want a reflection-like introspection ability from within one component, to load another component, work out what it needs to instantiate, and invent/plug that in before starting it?
This one—when loading in a component, being able to supply the Linker with another component and have its exports satisfy whatever imports it can.
Chris Fallin (Oct 29 2024 at 18:30):can you unpack "whatever imports it can" a bit -- is this a best-effort thing, where we're duck-type-matching things up and there may be some missing pieces? or is there a step in this system where we inspect the component, see it wants a world W with imports A, B, C, and put together exactly those?
Julia DeMille (Oct 29 2024 at 18:34):Take the regex and validator components from the composing components page as an example. They would be matched based on the WIT, I suppose.
If there are imports not defined by a provided component, it would be on the user to define those before instantiating, as normal.
Joel Dice (Oct 29 2024 at 19:00):Possibly relevant: https://github.com/rylev/wepl
From the Features section:
Satisfying imports with other WebAssembly Components
Julia DeMille (Oct 29 2024 at 19:00):Joel Dice said:
Possibly relevant: https://github.com/rylev/wepl
Will take a look, thanks
Julia DeMille (Oct 30 2024 at 01:16):That crate uses wasm_compose, which has been superseded by wac. I guess I could try to work out how wac works.
Ralph (Oct 30 2024 at 09:11):it's all just code.
Julia DeMille (Nov 01 2024 at 05:25):It looks like plug in the wac-graph crate is the most notable function. It's doing... effectively what I planned to do?
Julia DeMille (Nov 01 2024 at 05:26):It is using a graph instead of wasmtime's linker model, though. Still, shouldn't be terribly hard to adapt.
Lann Martin (Nov 01 2024 at 12:44):Yes, wac plug does what it sounds like you're trying to do except statically, producing a new component. Based on my (limited) understanding of the wac-graph code I'm not sure that it will be directly translatable to the wasmtime Linker, but others might have a better understanding there.
Last updated: Dec 23 2024 at 13:07 UTC