Compatibility with wasm

[silicology1]

Can megalodon-rs support wasm so that it can used by rust framework like yew?

[h3poteto]

Please read: #53

[h3poteto]

duplicated

[silicology1]

Still it doesn't support error

megalodon= {version="0.11.8"}

error[E0432]: unresolved import crate::sys::IoSourceState
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/io_source.rs:12:5
|
12 | use crate::sys::IoSourceState;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ no IoSourceState in sys

error[E0432]: unresolved import crate::sys::tcp
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/net/tcp/listener.rs:15:17
|
15 | use crate::sys::tcp::{bind, listen, new_for_addr};
| ^^^ could not find tcp in sys

error[E0432]: unresolved import crate::sys::tcp
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/net/tcp/stream.rs:13:17
|
13 | use crate::sys::tcp::{connect, new_for_addr};
| ^^^ could not find tcp in sys

error[E0433]: failed to resolve: could not find Selector in sys
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/poll.rs:312:18
|
312 | sys::Selector::new().map(|selector| Poll {
| ^^^^^^^^ could not find Selector in sys

error[E0433]: failed to resolve: could not find event in sys
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/event/event.rs:24:14
|
24 | sys::event::token(&self.inner)
| ^^^^^ could not find event in sys

error[E0433]: failed to resolve: could not find event in sys
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/event/event.rs:38:14
|
38 | sys::event::is_readable(&self.inner)
| ^^^^^ could not find event in sys

error[E0433]: failed to resolve: could not find event in sys
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/event/event.rs:43:14
|
43 | sys::event::is_writable(&self.inner)
| ^^^^^ could not find event in sys

error[E0433]: failed to resolve: could not find event in sys
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/event/event.rs:68:14
|
68 | sys::event::is_error(&self.inner)
| ^^^^^ could not find event in sys

error[E0433]: failed to resolve: could not find event in sys
--> /home/amiya/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mio-0.8.10/src/event/event.rs:99:14
|
99 | sys::event::is_read_closed(&self.inner)
| ^^^^^ could not find event in sys

[anderspitman]

@h3poteto would you consider re-opening this? In order for megalodon to work in wasm, I believe more functionality is required. I haven't yet managed to get reqwest to work from wasm. oauth2-rs support providing your own FnOnce for making HTTP requests. Using that I was able to get oauth2-rs and openidconnect-rs to work. Does megalodon currently support any sort of similar flow?

[h3poteto]

No.
I've tried to build megalodon with wasm, but it was the same.

[anderspitman]

In the last few weeks I found another library that follows a similar pattern to oauth2-rs/openidconnect-rs: https://github.com/sugyan/atrium. Atrium makes multiple network requests internally, but it's simple to provide your own implementations for the network calls. For example you can see here the relatively few lines of code necessary for me to implement my own HTTP client function for wasm32 (running in Extism):

https://github.com/lastlogin-net/decent-auth-rs/blob/176bb8737179de9bfeecf9424a4354d91f06cbd0/src/atproto.rs#L283

This allowed me to add Bluesky/ATProto login to my library with far less effort and increased security.

I believe this is similar to the concept of sans-io development, but I'm not an expert in that. Would you be interested in adding this sort of flexibility to megalodon?

[h3poteto]

Hmm, in the first place, why do you want to use megalodon-rs with wasm?
Why not JavaScript version megalodon? https://github.com/h3poteto/megalodon

[anderspitman]

I'm actually targeting backend, not frontend. I'm building an authentication library for multiple languages. Currently have it working for JS, Go, and Rust, but adding support for any of the Extism host languages (https://extism.org/) should be relatively straight forward.

[h3poteto]

If it's backend, why do you need to use wasm instead of compiling with rust?

[anderspitman]

You mean compile the Rust to FFI via extern C? Primarily because wasm is far more portable (especially for JS and Golang). You can run the same wasm binary unchanged on many platforms and languages.

[h3poteto]

Sorry, I don't really get it, why do you need wasm if you're targeting the backend?

[anderspitman]

Say I'm building a JS app and want to add ATProto login. I need to find a JS library that supports that. Next imagine I'm writing a Golang app and want to do the same thing. Now I need to find a completely different library, which likely has a different feature set. The library I'm working on works in JS, Golang, Rust, and others are easy to add. It also supports login with ATProto, Fediverse, OIDC, etc. One auth library that provides a consistent feature set and API in many languages.

If I wasn't using wasm, I would have to implement each feature in every language. Using wasm I implement a feature once and it immediately works in every language. Building for wasm is the best way I've found to accomplish this.

[h3poteto]

But to do that, each library needs to be wasm-compatible, right?
It would be fine if it were very easy, but isn't this just pushing the costs of implementing it onto the libraries side?