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@ -7,24 +7,24 @@ tags: [rust, javascript, webassembly]
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---
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Forgive me, but this is going to be a bit of a schizophrenic post. I both despise Javascript and the
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modern ECMAScript ecosystem, and I'm stunned by its success at doing some things I think are really cool.
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And it's [this duality](https://www.destroyallsoftware.com/talks/the-birth-and-death-of-javascript)
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that led me to a couple of (very) late nights over the past weeks trying to reconcile myself.
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modern ECMAScript ecosystem, and I'm stunned by its success doing some really cool things.
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It's [this duality](https://www.destroyallsoftware.com/talks/the-birth-and-death-of-javascript)
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that's led me to a couple of (very) late nights over the past weeks trying to reconcile myself as
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I try to bootstrap a simple desktop application.
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See, as much as [Webassembly isn't trying to replace Javascript](https://webassembly.org/docs/faq/#is-webassembly-trying-to-replace-javascript),
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**I want Javascript gone**. There are plenty of people who do not share my views, and they are probably
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nicer and more fun at parties. But I cringe every time "Webpack" is mentioned, and I think it's hilarious
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that the [language specification](https://ecma-international.org/publications/standards/Ecma-402.htm)
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dramatically outpaces anyone's [actually implementing](https://kangax.github.io/compat-table/es2016plus/)
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the spec. The answer to this conundrum is of course to recompile code from newer versions of the language to
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older versions. At least [Babel] is a nice tongue-in-cheek reference.
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dramatically outpaces anyone's [actual implementation](https://kangax.github.io/compat-table/es2016plus/).
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The answer to this conundrum is of course to recompile code from newer versions of the language to
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older versions *of the same language* before running. At least [Babel] is a nice tongue-in-cheek reference.
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Yet for as much hate as [Electron] receives, it does a stunningly good job at solving
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a really hard problem: *how the hell do I put a button on the screen and react when the user clicks it*?
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GUI programming is hard, straight up. But if browsers are already able to run everywhere, why don't
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we take advantage of someone else solving the hard problems for us? Don't reinvent wheels. I don't like
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that I have to use Javascript for it, but I apparently don't mind Javascript enough that I feel inclined to
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whip out good ol' [wxWidgets].
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we take advantage of someone else solving the hard problems for us? I don't like that I have to use
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Javascript for it, but I really don't feel inclined to whip out good ol' [wxWidgets].
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Now there are other native solutions ([libui-rs], [conrod], [oh hey wxWdidgets again!][wxRust]),
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but those also potentially have their own issues with distribution, styling, etc.
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@ -39,24 +39,24 @@ Instead, **what would it take to get to a point where we can skip Javascript in
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# Setting the Stage
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Truth is, WASM/Webassembly is a pretty new technology and I'm generally unfamiliar with the tools.
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Truth is, WASM/Webassembly is a pretty new technology and I'm a total beginner in this area.
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There may already be solutions to the issues I discuss, but I'm totally unaware of them,
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so I'm going to try and organize what I know exists.
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so I'm going to try and organize what I did manage to discover.
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I should also mention that the content and things I'm talking about here are not intended to be prescriptive,
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but more "if someone else is interested, what do we already know doesn't work?" *I expect everything in this post to be obsolete
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within two months.* Even over the course of writing this, [a blog post](https://mnt.io/2018/08/28/from-rust-to-beyond-the-asm-js-galaxy/)
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was invalidated because [upstream changes](https://github.com/WebAssembly/binaryen/pull/1642)
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broke [a Rust tool](https://github.com/rustwasm/wasm-bindgen/pull/787) that ultimately
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[forced changes in the blog post](https://mnt.io/2018/08/28/from-rust-to-beyond-the-asm-js-galaxy/#comment-477).
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**And all that happened within the span of a week.** Things are moving quickly.
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within two months.* Even over the course of writing this, [another blog post](https://mnt.io/2018/08/28/from-rust-to-beyond-the-asm-js-galaxy/)
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had to be modified because [upstream changes](https://github.com/WebAssembly/binaryen/pull/1642)
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broke a [Rust tool](https://github.com/rustwasm/wasm-bindgen/pull/787) that the post tried to use.
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The post [was fixed](https://mnt.io/2018/08/28/from-rust-to-beyond-the-asm-js-galaxy/#comment-477),
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**but all this happened within the span of a week.** Things are moving quickly.
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I'll also note that we're going to skip [asm.js] and [emscripten]. Truth be told, I couldn't get either of these
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to output anything, and so I'm just going to say [here be dragons.](https://en.wikipedia.org/wiki/Here_be_dragons)
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Everything I'm discussing here is using the `wasm32-unknown-unknown` target.
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And the code that I *did* get running is available [over here](https://github.com/bspeice/isomorphic_rust).
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Feel free to use that as a starting point, but I'm mostly including the link as a reference point for the things
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The code that I *did* get running is available [over here](https://github.com/bspeice/isomorphic_rust).
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Feel free to use it as a starting point, but I'm mostly including the link as a reference point for the things
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that were attempted.
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# An Example Running Application
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@ -65,7 +65,7 @@ So, I did *technically* get a running application:
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...which you can also try out if you want to:
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...which you can also try out if you want:
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```sh
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git clone https://github.com/bspeice/isomorphic_rust.git
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@ -73,22 +73,22 @@ cd isomorphic_rust/percy
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yarn install && yarn start
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```
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...but I really wouldn't use this as a "high quality" starting point. It's mostly just there
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to prove that this is possible in the first place. And that's something to be proud of!
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...but I wouldn't really call it a "high quality" starting point to base future work on. It's mostly there
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to prove this is possible in the first place. And that's something to be proud of!
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There's a huge amount of engineering that went into showing a window with the text "It's alive!".
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There's also a lot of usability issues that prevent me from recommending anyone try using Electron and WASM
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There's also a lot of usability issues that prevent me from recommending anyone try Electron and WASM apps
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at the moment, and I think that's the more important thing to discuss.
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# Issue the First: Complicated Toolchains
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I quickly established that [wasm-bindgen] was necessary to "link" my Rust code to Javascript. At that point
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you've got an Electron app that starts an HTML page which fetches Javascript. To keep things simple, the goal
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was to package everything using [webpack] so that I could just load a `bundle.js` file on the page.
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you've got an Electron app that starts an HTML page which ultimately fetches your WASM blob. To keep things simple,
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the goal was to package everything using [webpack] so that I could just load a `bundle.js` file on the page.
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That decision was to be the last thing that kinda worked in this process.
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The first issue [I ran into](https://www.reddit.com/r/rust/comments/98lpun/unable_to_load_wasm_for_electron_application/)
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while attempting to link things via Webpack is a detail in the WebAssembly spec:
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while attempting to bundle everything via Webpack is a detail in the WebAssembly spec:
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> This function accepts a Response object, or a promise for one, and ...
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> **[if it] does not match the `application/wasm` MIME type**, the returned promise
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@ -96,9 +96,9 @@ while attempting to link things via Webpack is a detail in the WebAssembly spec:
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> [WebAssembly - Additional Web Embedding API](https://webassembly.org/docs/web/#additional-web-embedding-api)
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Specifically, if you try and load a WebAssembly blob without the MIME type set, you'll get an error.
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On the web, this isn't a huge issue because you actually have a server delivering the blob. With Electron,
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you're resolving things with a `file://` URL, and thus can't control the MIME type:
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Specifically, if you try and load a WASM blob without the MIME type set, you'll get an error.
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On the web, this isn't a huge issue because you have a server that can set MIME types delivering the blob.
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With Electron, you're resolving things with a `file://` URL and thus can't control the MIME type:
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@ -106,9 +106,9 @@ There are a couple of solutions depending on how far into the deep end you care
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- Embed a static file server in your Electron application
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- Use a [custom protocol](https://electronjs.org/docs/api/protocol) and custom protocol handler
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- Host your WASM blob on a website, thus tying your users to the internet
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- Host your WASM blob on a website that you resolve at runtime
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But all of these are pretty bad solutions and defeat the purpose of using WASM in the first place. Instead,
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But all these are pretty bad solutions and defeat the purpose of using WASM in the first place. Instead,
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my workaround was to [open a PR with webpack](https://github.com/webpack/webpack/issues/7918) and
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use regex to remove calls to `instantiateStreaming` in the
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[build script](https://github.com/bspeice/isomorphic_rust/blob/master/percy/build.sh#L21-L25):
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@ -121,8 +121,8 @@ cargo +nightly build --target=wasm32-unknown-unknown && \
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sed -i 's/.*instantiateStreaming.*//g' "$APP_DIR/bundle.js"
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```
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On a brighter note, once [another Webpack PR](https://github.com/webpack/webpack/pull/7983) lands,
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the [build process](https://github.com/bspeice/isomorphic_rust/blob/master/percy_patched_webpack/build.sh#L24-L27)
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Once that lands though, the
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[build process](https://github.com/bspeice/isomorphic_rust/blob/master/percy_patched_webpack/build.sh#L24-L27)
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becomes more straight-forward:
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```sh
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@ -132,36 +132,36 @@ cargo +nightly build --target=wasm32-unknown-unknown && \
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"$DIR/node_modules/webpack-cli/bin/cli.js" --mode=production "$APP_DIR/app_loader.js" -o "$APP_DIR/bundle.js"
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```
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But we're not done yet! After we compile Rust into WASM and link WASM to JS (via `wasm-bindgen` and `webpack`),
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we still have to make an Electron app. For this purpose I used an Electron starter app from [Electron Forge],
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But we're not done yet! After we compile Rust into WASM and link WASM to Javascript (via `wasm-bindgen` and `webpack`),
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we still have to make an Electron app. For this purpose I used an Electron starter from [Electron Forge],
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and then a [`prestart` script](https://github.com/bspeice/isomorphic_rust/blob/master/percy/package.json#L8)
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to actually handle the build process.
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So the [final toolchain](https://github.com/bspeice/isomorphic_rust/blob/master/percy/package.json#L8)
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The [final toolchain](https://github.com/bspeice/isomorphic_rust/blob/master/percy/package.json#L8)
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looks something like this:
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- `yarn start` triggers the `prestart` script
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- `prestart` checks for missing tooling (`wasm-bindgen-cli`, etc.) and then:
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- `prestart` checks for missing tools (`wasm-bindgen-cli`, etc.) and then:
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- Uses `cargo` to compile the Rust code into WASM
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- Uses `wasm-bindgen` to link the WASM blob into a Javascript file with exported symbols
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- Uses `webpack` to bundle the page start script with the Javascript we just generated
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- Uses `babel` under the hood to compile the `wasm-bindgen` down from ES6 to something browser-compatible
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- The `start` script actually runs an Electron Forge handler to do some sanity checks
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- Uses `babel` under the hood to compile the `wasm-bindgen` code down from ES6 into something browser-compatible
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- The `start` script runs an Electron Forge handler to do some sanity checks
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- Electron actually starts
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...which is complicated. I think more work needs to be done to either build a high-quality starter app that
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can manage these steps, or something tool "just handles" the complexity of linking a compiled WASM file into
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can manage these steps, or another tool that "just handles" the complexity of linking a compiled WASM file into
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something the browser can run.
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# Issue the Second: WASM tools in Rust
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For as much as I didn't enjoy the Javascript tooling needed to interface with Rust, the Rust-only bits aren't
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any better at the moment. I get it, a lot of projects are just starting off, and that leads to a fragmented
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ecosystem. So here's what I can recommend as a starting point:
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ecosystem. Here's what I can recommend as a starting point:
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Don't check in your `Cargo.lock` files to version control. If there's a disagreement between the
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version of `wasm-bindgen-cli` you have installed and the `wasm-bindgen` you're compiling with in `Cargo.lock`,
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you can get a nasty error:
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you get a nasty error:
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```
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it looks like the Rust project used to create this wasm file was linked against
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@ -175,10 +175,10 @@ exactly match, so it's required that these two version are kept in sync by
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either updating the wasm-bindgen dependency or this binary.
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```
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Not that I managed to run into this error myself (*coughs nervously*).
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Not that I ever managed to run into this myself (*coughs nervously*).
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There are two projects attempting to be "frameworks": [percy] and [yew]. Between those, I managed to get
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[two](https://github.com/bspeice/isomorphic_rust/tree/master/percy)
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There are two projects attempting to be "application frameworks": [percy] and [yew]. Between those,
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I managed to get [two](https://github.com/bspeice/isomorphic_rust/tree/master/percy)
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[examples](https://github.com/bspeice/isomorphic_rust/tree/master/percy_patched_webpack) running
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using `percy`, but was unable to get an [example](https://github.com/bspeice/isomorphic_rust/tree/master/yew)
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running with `yew` because of issues with "missing modules" during the `webpack` step:
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@ -193,7 +193,7 @@ Module not found: Error: Can't resolve 'env' in '/home/bspeice/Development/isomo
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```
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If you want to work with the browser APIs directly, your choices are [percy-webapis] or [stdweb] (or eventually [web-sys]).
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See above for my `percy` examples, but when I [tried to use `stdweb`](https://github.com/bspeice/isomorphic_rust/tree/master/stdweb),
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See above for my `percy` examples, but when I tried [an example with `stdweb`](https://github.com/bspeice/isomorphic_rust/tree/master/stdweb),
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I was unable to get it running:
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```sh
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@ -207,25 +207,25 @@ Module not found: Error: Can't resolve 'env' in '/home/bspeice/Development/isomo
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At this point I'm pretty convinced that `stdweb` is causing issues for `yew` as well, but can't prove it.
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I did also get a [minimal example](https://github.com/bspeice/isomorphic_rust/tree/master/minimal) running
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that doesn't depend on any frameworks, just `wasm-bindgen`. It would require manually writing "`extern C`"
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that doesn't depend on any tools besides `wasm-bindgen`. It requires manually writing "`extern C`"
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blocks for everything in the browser though, so I don't recommend it.
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Finally, from a tools and platform view, there are two up-and-coming packages that should be mentioned:
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[js-sys] and [web-sys]. Their purpose is to be a low-level building block that simply exposes the browser's APIs
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to Rust. If you're interested in building a web app framework from scratch, these should give you the most
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flexibility. I didn't touch either for this post, though I expect them to be essential long-term.
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[js-sys] and [web-sys]. Their purpose is to be fundamental building blocks that simply exposes the browser's APIs
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to Rust. If you're interested in building a app framework from scratch, these should give you the most
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flexibility. I didn't touch either in my research, though I expect them to be essential long-term.
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So there's a lot in play from the Rust side of things, and it's just going to take some time to figure out
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what works and what doesn't.
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# Issue the Third: Known Unknowns
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Alright, so after I managed to get an application started, I stopped there. It was an incredible amount of effort
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to chain together everything that was needed, and at this point I'd rather learn [Typescript] than keep
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Alright, so after I managed to get an application started, I stopped there. It was an good deal of effort
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to chain together even a proof of concept, and at this point I'd rather learn [Typescript] than keep
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trying to maintain an incredibly brittle pipeline. Blasphemy, I know...
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The important point I want to make is that there's a lot unknown about how any of this would hold up outside
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of proofs of concept. Things I didn't attempt:
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The important point I want to make is that there's a lot unknown about how any of this holds up outside
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proofs of concept. Things I didn't attempt:
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- Testing
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- Packaging
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@ -235,7 +235,7 @@ of proofs of concept. Things I didn't attempt:
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# What it Would Take
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Much as I don't like Javascript, the tools are too shaky for me to recommend mixing Electron and WASM
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at the moment. There's a lot of innovation happening here, so who knows? Someone might have an application
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at the moment. There's a lot of innovation happening, so who knows? Someone might have an application
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in production a couple months from now. But at the moment, I'm personally going to stay away.
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Let's finish with a wishlist then - here are the things that I think need to happen before Electron/WASM/Rust
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@ -245,10 +245,11 @@ can become a thing:
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- Browser API libraries ([web-sys] and [stdweb]) need to make sure they can support running in Electron (see module error above)
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- Projects need to stabilize. There's talk of `stdweb` being turned into a Rust API
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[on top of web-sys](https://github.com/rustwasm/team/issues/226#issuecomment-418475778), and percy
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[moving to web-sys](https://github.com/chinedufn/percy/issues/24)
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[moving to web-sys](https://github.com/chinedufn/percy/issues/24), both of which are pretty big changes
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- `wasm-bindgen` is great, but still in the "move fast and break things" phase
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- A good "boilerplate" app would dramatically simplify the start costs; [electron-react-boilerplate](https://github.com/chentsulin/electron-react-boilerplate)
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comes to mind
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- A good "boilerplate" app would dramatically simplify the start-up costs;
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[electron-react-boilerplate](https://github.com/chentsulin/electron-react-boilerplate)
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comes to mind as a good project to imitate
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- More blog posts/contributors! I think Electron + Rust could be cool, but I have no idea what I'm doing
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[wxwidgets]: https://wxwidgets.org/
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Loading…
Reference in New Issue