wasmtime

Yup. In addition to JavaScript runtimes that have added WebAssembly support, such as Node, there are dedicated WebAssembly runtimes, like wasmtime: https://github.com/bytecodealliance/wasmtime If you want to provide a plugin or extension interface, and want to give those plugins a limited interface rather than making them all-powerful, embedding a WebAssembly runtime gives you all of that plus the ability for people to easily write plugins in any language. Also see https://hacks.mozilla.org/2019/08/webassembly-interface-type... for an illustrated description of how that'll work smoothly across languages.

For anyone curious, the actual .NET Wasmtime package source is here: https://github.com/bytecodealliance/wasmtime/tree/master/cra...

That's not what the parent was asking. They were asking if WASM has an FFI interface for runtimes that want to not execute the WASM code entirely sandboxed from the host, but rather want to allow you to dlload(2) code into the OS process hosting the WASM interpreter and call it through WASM ops. Presumably, https://github.com/CraneStation/wasmtime would benefit from such an FFI API being specified.

I'm very happy to see the WebIDL proposal replaced with something generalized. The article brings up an interesting point: Webassembly really could enable seamless cross-language integration in the future. Writing a project in Rust, but really want to use that popular face detector written in Python? And maybe the niche language tokenizer written in PHP? And sprinkle ffmpeg on top, without the hassle of target-compatible compilation and worrying about use after free vulnerabilities? No problem use one of the many WASM runtimes popping up (like [1], [2]) and combine all those libraries by using their pre-compiled WASM packages distributed on a package repo like WAPM [2], with auto-generated bindings that provide a decent API from your host language. Sounds too good to be true? Probably, and there are plenty of issues to solve. But it sou

As wasm is designed compatibly with capability security, that's not a crazy idea. (See e.g. the first section of https://github.com/CraneStation/wasmtime/blob/master/docs/WA...)

Interesting to compare this to the Hello World that's now possible with WASI and its fd_write function: https://github.com/CraneStation/wasmtime/blob/e530a582afe6a2...

This seems to be the current documentation: https://github.com/CraneStation/wasmtime/blob/master/docs/WA...

From what I gather the thing is based on WASI which in early beta and for which many parts don't exist or don't work, networking and file access being a few of those [1]: Note that everything here is a prototype, and while a lot of stuff works, there are numerous missing features and some rough edges. One big thing that's not done yet is the actual mechanism to provide a directory as a pre-opened capability, to allow files to be opened. Some of the pieces are there (__wasilibc_register_preopened_fd) but they're not used yet. Networking support is also incomplete. In other words, this is a somewhat premature announcement when it comes to fulfilling those promises. [1] https://github.com/CraneStation/wasmtime/blob/master/docs/WA...

Wasm is split between wasm32 and wasm64 they are separate https://github.com/WebAssembly/design/blob/master/FutureFeat... So yes, we're at the lowest common denominator for addressing memory. You would need to explicitly build for wasm64 in the future. Within wasmer wasm is compiled into a different IR through cranelift. That generally compiles for 64 bit systems but can compile to 32: https://github.com/CraneStation/wasmtime/pull/44 Not sure if this entirely answers your question. Seems like there are still a handful for decisions wasmer would need to make in terms of what exactly is supported.