Remix.run Logo
The Road to the WASM Component Model 1.0(bytecodealliance.org)
70 points by emschwartz 3 days ago | 44 comments
simonw 4 hours ago | parent | next [-]

I'm unreasonably excited about WASI. WASI is the thing which takes WebAssembly from a tool for running stuff in a browser to a tool that can run entire portable sandboxed applications on a computer - with controlled filesystem and network access.

I don't ever want to run untrusted code from the internet outside of a sandbox ever again. If WASI lives up to its full potential I won't have to - we'll have a robust, cross-platform sandboxing solution for running real applications.

samiv 2 minutes ago | parent | next [-]

Sorry but how exactly does the sandboxing help? You download and run an app that you expect to be useful and that you need. The app needs permission to access your data. If you want to use the application what choice do you have except to grant it access?

Point being you wouldn't run untrusted code in the first place and for "trusted code" you end up accepting it's access requirements anyway.

So logically I'd think that the malware would just get piggy bagged into actual non-obvious utility apps and nothing is gained.

Second problem is that the security model hoops make for terrible APIs and user experiences. Just look at the current filesystem browser APIs. It must be mentally challenging to design APIs to Be usable and the nerf them for security purposes to make them "not too usable".

Panzerschrek 2 hours ago | parent | prev | next [-]

> I don't ever want to run untrusted code from the internet outside of a sandbox ever again

WASM is great, but I think it's a wrong approach for sandboxing problem. It's technically possible to sandbox native applications (compiled into target machine code) using OS-builtin mechanisms, but it's not done for compatibility reasons, because this is the way things were done last 50 years or so.

tancop 2 hours ago | parent | next [-]

sandboxing native apps just gives you security. with wasm you also get a single portable binary that can run on x86 windows, arm64 linux and in your browser with zero modification. you dont need to write platform specific code or use third party frameworks.

pjmlp an hour ago | parent | next [-]

No you don't, because WASM is only compute, and you need exactly runtime specific code and third party frameworks for everything else as imported functions.

Panzerschrek an hour ago | parent | prev [-]

> you dont need to write platform specific code

You don't need to write platform-specific code if you use some cross-platform framework. For simple programs it may be enough to use only the standard library of your language of choice.

> single portable binary that can run on x86 windows, arm64 linux and in your browser with zero modification

It has little value. Compiling a separate binary for each OS isn't that hard, since only a handful of architectures and operating systems are actually in use. Using an abstract cross-platform binary (like WASM) in the other hand adds extra performance costs and other user-side overhead, which isn't strictly necessary.

rvz an hour ago | parent | prev [-]

Exactly. It is entirely a misconception to believe that WASM is this silver bullet on sandboxing and it is not that great security-wise I’m afraid.

It is only now being inspected by researchers and attackers who have found sandbox escapes [0] (chrome 0day), out-of-bounds [1] / use-after-free [2] and many other [3] flaws [4] in WebAssembly which I also agree that it is not enough for sandboxing at all.

[0] https://nvd.nist.gov/vuln/detail/CVE-2026-11645

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=2009901

[2] https://bugzilla.mozilla.org/show_bug.cgi?id=2013741

[3] https://www.miggo.io/vulnerability-database/cve/CVE-2026-269...

[4] https://github.com/bytecodealliance/wasm-micro-runtime/secur...

hobofan an hour ago | parent [-]

Those are not flaws in WASM itself, but in different WASM runtimes.

DanielHB an hour ago | parent | prev | next [-]

Use cases I am more excited about:

1) Replace webhooks in web apps with wasm binaries provided by the customer, but that run in the web app servers.

2) Safer plugin system for professional software (plugins for photoshop, plugins for IDEs, etc)

3) Safer mod system for games and server-side mods that run on the game-maker server.

bzzzt 19 minutes ago | parent | next [-]

We had that in the 90's with Java. Why would this approach succeed today?

crabmusket 15 minutes ago | parent | prev | next [-]

Check out https://extism.org, it is built for those kinds of use cases. However I think WASI and components could enhance it.

tuananh 44 minutes ago | parent | prev [-]

i had this same vision when i created hyper-mcp with modular plugin system via WASM plugins. Too bad, the community moves on from MCP to CLI with coding agent

https://github.com/hyper-mcp-rs/hyper-mcp

yjftsjthsd-h an hour ago | parent | prev | next [-]

Hey, this is also my interest. I was just looking into whether it was possible to e.g. build an archive extractor that runs like a normal program but does the actual extraction completely in wasm. Unfortunately, AFAICT it's possible but requires custom code; you can't (yet, I hope) just compile unzip/libarchive/whatever with CC=wasicompiler and get a sandboxed binary. But we're getting close.

nl 40 minutes ago | parent [-]

What do you mean? You absolutely can run compression in WASM.

For example here is Gzip in WASM: https://github.com/ColinTimBarndt/wasm-gzip

grayrest an hour ago | parent | prev | next [-]

The thing that interests me the most is that execution is deterministic. If the inputs to a WASM module are logged you get durable execution and rr style reverse debugging as part of the package.

emadda an hour ago | parent | prev | next [-]

I like the technical design of WASM, but I feel that better OS sandboxes for regular native code will be the common approach to running untrusted code.

As soon as you compile to WASM you no longer have the C FFI and the ability to call the OS systems interfaces for files, network and others.

It is extra work to move something to WASM vs just compiling it and running it in a sandbox.

wyager 2 hours ago | parent | prev [-]

I'm curious if people have a good story for why WASI will succeed where Java failed

simonw 2 hours ago | parent | next [-]

My main one is that WASI has benefitted from an additional 31 years of accumulated industry-wide experience compared to when Java was first released.

Panzerschrek an hour ago | parent | prev | next [-]

Programs written in Java require installation of a middleware called Java runtime. It adds extra friction for end-users. And even if one has Java runtime installed, a newer version may be necessary for a recently-published application.

With WASM it may be the same, unless al major OS vendors integrate a WASM runtime so that it doesn't need to be installed separately.

bzzzt 17 minutes ago | parent | next [-]

> Programs written in Java require installation of a middleware called Java runtime. It's possible to link or embed a Java runtime in an existing application.

pjmlp an hour ago | parent | prev [-]

It is exactly the same for WASM outside of the browser, and Java has Android as counter part to built in runtime.

auggierose 40 minutes ago | parent [-]

Yes, but inside the browser is a freaking big use case.

pjmlp 38 minutes ago | parent [-]

Not really, I don't need COM / CORBA on the browser.

fla an hour ago | parent | prev [-]

My main one is: distribution & access. If major browsers implement the WASI runtime then using and distributing a WASI app will be way simpler than the Java equivalent ever was.

thefounder 3 hours ago | parent | prev | next [-]

It’s great we are past the “wasm is not replacing JavaScript” phase. Or “you don’t need DOM for wasm . That’s what JavaScript is for”

flohofwoe an hour ago | parent [-]

I'm pretty sure you'll will still need a JS shim to talk to most web APIs. For instance the Mozilla DOM experiments seems to use a special JS variant with a 'use component' header (similar to the old 'use asm' for asm.js) as shim, but the JS shim is still there. The component model can marshal 'record types' between different WASM modules, but AFAIK not between a WASM module and a web API.

baudaux an hour ago | parent | prev | next [-]

I will be interested in getting details about the experiments of Ryan Hunt about DOM performances.

I am currently developing a WASI runtime for exaequOS and Woua programming language that will target WASI and will have access to DOM through a virtual/dev/dom driver.

wex —dir /dev /usr/tests/woua/dom_demo.wasm

catlifeonmars 44 minutes ago | parent | prev | next [-]

I’m curious if this helps make WASM a potential alternative to eBPF for userspace kernel extensions.

pjmlp an hour ago | parent | prev | next [-]

So, Jini with RMI, CORBA, DCOM, and gRPC, hello again.

Really leave WASM on the browser.

rohitsriram 2 hours ago | parent | prev | next [-]

The microkernel analogy for the Component Model vs WASI is actually a really useful mental model that I hadn't seen framed that way before. Component Model as the always-present kernel, WASI as optional OS services on top. That framing makes it obvious why browser implementation of the Component Model is tractable even though browsers have strong opinions about I/O, and why 1.0 for the Component Model and WASI are separate milestones. The lazy ABI change is also underrated, zero-copy forwarding between calls is going to matter a lot for the use cases where WASM actually competes with native.

mastermage an hour ago | parent | prev | next [-]

Oh yes give me the component model lets go.

wyager 2 hours ago | parent | prev | next [-]

Very exited about WASM/WCM as a portable format for capability-secure applications.

I had a spec file sitting around for an OS project idea I had, where the kernel would just be the WASM compiler + a few small shim drivers, and everything else (including e.g. PCIe device drivers) would be WASM modules with WIT interface specs. I handed the spec off to Fable and it seems to have made a working proof-of-concept. Has a maximally-WASM OS running on browser/QEMU/Orange Pi. https://eo9.org

flohofwoe an hour ago | parent | prev | next [-]

> The Component Model can’t formally reach 1.0 without native implementation in at least two browser engines.

I don't quite understand why the Component Model is now suddenly a browser thing, and on top something that needs to be implemented natively in browsers instead of a convention between different compiler toolchains.

Keep that boondoggle in WASI and the Bytecode Alliance. WASM in the browser works just fine without the added runtime complexity.

shevy-java 3 hours ago | parent | prev | next [-]

WASM first appeared in 2017.

It still hasn't really reached a breakthrough.

Billions use HTML+CSS+JavaScript. Who really uses WASM? There are of course users, but very, very few in absolute numbers. Many projects are not web-based really. For Autodesk Fusion, as one example for many, I have some mega-slow application that takes forever to work with in some cases on my laptop (it is not the fastest laptop, but I recently tested this on a faster desktop computer with 32GB RAM and it is still slow to no ends; using it all WASM based would be even slower I bet. That's not winning anyone over ...).

simonw 2 hours ago | parent | next [-]

According to https://chromestatus.com/metrics/feature/timeline/popularity... WebAssembly runs on about 6.11% of Chrome page loads, up from 3.37% in January 2024.

Deukhoofd an hour ago | parent | prev | next [-]

When I last played with it checking out its capabilities, I found the thing I was mostly missing to really make use of it was the thing referenced in this article, the Component Model. Without a type model and binary specifications, interop was made a lot harder than it'd have been otherwise. Now that that's in, it becomes a lot more useful.

I was mostly looking at it for its state as being a cross-platform supported output platform of bytecode that's fairly well sandboxed. That makes it an excellent target for things like running untrusted plugins in an application in a performant manner.

h4ch1 3 hours ago | parent | prev | next [-]

I wrote an Unreal file parser in C# and use it in our in-house web based DAM. It was much more ergonomic and performant than writing it in Javascript.

esafak 3 hours ago | parent | prev | next [-]

WASM made Figma.

aatd86 3 hours ago | parent | prev [-]

WASM is super useful for FFI in some env

fyrn_ 3 hours ago | parent | prev [-]

Please please please bring it to the browser. I'm so done with the terrible ergonomics of everything at the was bounary having to pretend it's JavaScript

flohofwoe 27 minutes ago | parent | next [-]

Pretty sure the JS shim is still needed to talk to web apis, even if it might look slightly different (the is a 'use component' now in the JS shim in Mozilla's experiment similar to the old 'use asm' for asm.js - at least that's what the post says).

enos_feedler 3 hours ago | parent | prev [-]

It works in the browser already: https://github.com/bytecodealliance/jco

jauntywundrkind 2 hours ago | parent [-]

It works in the browser already, by bundling another browser runtime engine into wasm. You need a whole fork of Mozilla's SpiderMonkey engine, compiled to wasm, running in whatever browser you have, to run wasm components today.

I confess I was quite frustrated at first when browsers all said no to wasi / wasm components. But honestly, it was the right call. It's taken so long to make wasm components happen, to get them far enough along to start really consider implementing. I can accept that as just the reality of what it takes for a small team to do such amazing work. I am so thankful for the folks who have kept this going, kept advancing.

But it's time now. 0.3 delivers an incredibly comprehensive & gorgeous suite of capabilities that offer a winning combination of characteristics (fast, lightweight, sandboxable, runtime composeable components) that is ideal for the web. I hope browsers can help get us set up for 1.0, help steer us forwards towards that spec, and I hope they're moving quickly towards being ready to implement!

enos_feedler an hour ago | parent [-]

I agree with you, but sadly without killer use cases in the browser this still ends up being quite political to adopt. I feel good about the approach being taken. The browser vendors have analytics on the usage of JCO and so despite it not being "ideal", it works. We need to make stuff using JCO and make those things popular. It's not on the browser vendors to build native component model yet. At some point I suspect it will be though.