design VS interface-types

WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable compilation target for programming languages, enabling deployment on the web for client and server applications. - https://webassembly.org

With WebAssembly we can compile our C++ codebase into a wasm module for the browser. So when you look at a SciChart.js chart you're actually seeing our C++ graphics engine wrapped for JavaScript.

I should add, however, that the unmentioned elephant in the room is V8 JIT (TurboFan), which simply doesn't handle irreducible control flow. While there are some valid theoretical arguments around the current arrangement in Wasm, looking at the history of the associated discussions makes it pretty obvious that having V8 support Wasm and generate fast code similar to what it can do for asm.js was an overriding concern in many cases. And Google straight up said that if Wasm has ICF, they will not bother supporting such cases, so it will be done by a much slower fallback:

https://github.com/WebAssembly/design/issues/796#issuecommen...

AFAIK no other Wasm implementation has the same constraint - the rest generally tend to desugar everything to jumps and then proceed from there. So this is, at least to some extent, yet another case of a large company effectively forcing an open standard to be more convenient for them specifically.

https://github.com/WebAssembly/design/issues/1397

> Currently allocating more than ~300MB of memory is not reliable on Chrome on Android without resorting to Chrome-specific workarounds, nor in Safari on iOS.

That's about allocating CPU memory but the GPU memory situation is similar.

As far as I can tell (5 minutes of internet research) this was to allow easier compilation to JavaScript as a fallback in the days when WASM wasn't widely supported.

"Please add goto" issue has been open since 2016:

https://github.com/WebAssembly/design/issues/796

Most interesting comment:

> The upcoming Go 1.11 release will have experimental support for WebAssembly. This will include full support for all of Go's features, including goroutines, channels, etc. However, the performance of the generated WebAssembly is currently not that good.

> This is mainly because of the missing goto instruction. Without the goto instruction we had to resort to using a toplevel loop and jump table in every function. Using the relooper algorithm is not an option for us, because when switching between goroutines we need to be able to resume execution at different points of a function. The relooper can not help with this, only a goto instruction can.

> It is awesome that WebAssembly got to the point where it can support a language like Go. But to be truly the assembly of the web, WebAssembly should be equally powerful as other assembly languages. Go has an advanced compiler which is able to emit very efficient assembly for a number of other platforms. This is why I would like to argue that it is mainly a limitation of WebAssembly and not of the Go compiler that it is not possible to also use this compiler to emit efficient assembly for the web.

^ https://github.com/WebAssembly/design/issues/796#issuecommen...

When I implemented a WASM compiler, the only source of float-based non-determinism I found was in the exact byte representation of NaN. Floating point math is deterministic. See https://webassembly.org/docs/faq/#why-is-there-no-fast-math-... and https://github.com/WebAssembly/design/blob/main/Nondetermini....

> To work with GC, you need some way to track if the GC'd object is accessible in WASM itself.

I've never heard of a GC with that kind of API. Usually any native code that holds a GC reference would either mark that reference as a root explicitly (eg. https://github.com/WebAssembly/design/issues/1459) or ensure that it can be traced from a parent object. Either way, this should prevent collection of the object. I agree that explicitly checking whether a GC'd object has been freed would not make any sense.

> The reason why you probably need a custom string type is so you can actually embed string literals without relying on interop with the environment.

WASM already has ways of embedding flat string data. This can be materialized into GC/heap objects at module startup. This must happen in some form anyway, as all GC-able objects must be registered with the GC upon creation, for them to be discoverable as candidates for collection.

Overall I still don't understand the issue. There is so much prior art for these patterns in native extensions for Python, PHP, Ruby, etc.

Giving you a buffer that grows is the allocation approach I am talking about. This is not how your OS works. Your OS itself works with an allocator that does a pretty good job making sure that your memory ends up not fragmented. Because WASM is in between, the OS is not in control of the memory, and instead the browser is. The browser implementation of "bring your own allocator" is cute but realistically just a waste of time for everybody who wants to deploy a wasm app because whatever allocator you bring is crippled by the overarching allocator of the browser messing everything up.

It seems like the vendors are recognizing this though, with firefox now having a discard function aparently!

https://github.com/WebAssembly/design/issues/1397

Some things that might greatly increase wasm usage and overall tooling:

1) Tools that run docker containers and serverless function services (like AWS lambda) to support providing a .wasm files instead

2) Garbage collection in the runtime to make GC languages easier to port to wasm

3) Dynamically typed languages (NodeJS, Python, Ruby) being able to compile to webassembly directly instead of porting the runtime to webassembly and then running the code through the runtime. This is a big ask though, basically needs to redesign the runtime completely

4) wasm-DOM bindings will enable other languages to do HTML rendering which will require new web frameworks for every language that wants to take over the space from JS. This will lead to (even more) fragmentation of the web ecosystem

5) A new wasm-first SDK (unrelated to the DOM) for building cross platform applications. I can see this taking off only if it is built-into the browsers and backed by some standards committee, so not very likely I think

6) Something like the Interface Types proposal ( https://github.com/WebAssembly/interface-types/blob/main/pro... ) becomes a thing allowing wasm programs to be consisted of modules written in several different languages and being able to call said modules with low or 0 runtime performance hit (and of course, no compilation to multiple CPU archs). So much of programming ecosystems are locked to specific languages (like data science with python) when there is little technical reason for it be like that.

AFAIK GC is irrelevant for "direct DOM access", you would rather want to hop into the following rabbit hole:

- reference types: https://github.com/WebAssembly/reference-types/blob/master/p...

- interface types (inactive): https://github.com/WebAssembly/interface-types/blob/main/pro...

- component model: https://github.com/WebAssembly/component-model

If this looks like a mess, that's because it is. Compared to that, the current solution to go through a Javascript shim doesn't look too bad IMHO.

I'm not really optimistic that particular aspect will get much improvement. Many people expected interface types to come save the day, but after a looong stagnation that proposal has been archived (for now) in favour of component types, which has much less potential for performance gains.

Really good questions. Unfortunately, most of the issues I found back then were fundamental ones. I've seen that Wasm has deprecated "Interface Types" and is now working on the "Component Model". But even then, as far as I understand that would only avoid the serialization and deserialization steps, and you would still need to copy complex types. It will be more performant, but I don't think it would be enough for Tremor either.

wasm doesn't know anything about the outside world on purpose. This allows it to be used in other domains. For direct access to the DOM et al, interface types are being developed. It's a non-trivial problem to interoperate with a dynamically typed GC'd language from any statically typed no-GC language that can compile to wasm.

You may want to look into WASM interface types, which is defining what amounts to am IDL for WASM and different languages have common calling conventions: https://hacks.mozilla.org/2019/08/webassembly-interface-type...

I don’t know if there’s a better intro article. I believe this is the current iteration of the proposal: https://github.com/WebAssembly/interface-types/blob/main/pro...

Yes, and if I'm not mistaken, this is the RFC

I see no reason why not. See the interface types proposal for a proposed solution.

Wanted to get thoughts from the Rust experts on this - the author of the Yew framework seems to think that Web Assembly Interface Types (https://github.com/WebAssembly/interface-types/blob/master/proposals/interface-types/Explainer.md) will allow Yew to eventually become faster than Vue, React, Angular, etc. Is there general consensus on this in the Rust community? The prospect of mixing Rust (for the performance critical pieces) with TS on the front end doesn't seem super appealing to me.