Server-Side Rendering Using WebAssembly

♪ Hello, everyone. I'm Shivai Lamba. I'm Wasim Edge Ambassador and also a TensorFlow.js SIG and Working Group Lead from India. Welcome to my talk at React Advanced. I'm presenting virtually from India. The title of my talk is server-side rendering using Web7b, so let's get started.

The first thing we'll talk about is how do we actually achieve server-side rendering. Now, the traditional ways is either to, let's say, use a React framework like NestJs that actually supports server-side rendering out of the box, or, if you are one of those engineers who would want to set up a server-side rendering manually, you could create a fresh Redux store on every request that gets sent out and then get this data out of the store and perform the server-side rendering, or another alternative way is also to actually set up a Express server that can be used to serve the contents from the build directory as static files to your front end.

So, first, before we move on to how you can achieve server-side rendering with WebAssembly, let's talk about WebAssembly a bit more. So, WebAssembly is a language that is neither related to web directly or related to the assembly language itself. What it is is really an efficient, low-level bytecode that is highly performant and is portable, secure, and language-agnostic compilation-tacked. So that means you can basically take any of your highly performant programming languages like C++, or even scripting languages such as Python or Go, and compile it into a WebAssembly bytecode that can be directly used. Now, why has it been so popular is that it can basically reduce some of the disadvantages that we have in terms of performance, especially with JavaScript. And can overcome those performance limitations by using the more performant programming languages like C++ or Rust, and converting them into WebAssembly, and then running them on the browser alongside JavaScript. And now WebAssembly is not just limited to the frontend or the browser, and finds a lot of different use cases in server-side and cloud applications as well.

And what is Wasmage? So Wasmage is a lightweight WebAssembly runtime that is primarily focused on building a lot of cloud-native and edge-based applications, and Wasmage is currently a CNC, which is the Cloud Native Computing Foundation Sandbox project. So, the question is that, how can WebAssembly be used to actually implement the server-side rendering? So, Wasmage, as we mentioned, it's the runtime for WebAssembly, especially for edge devices. The Wasmage JavaScript SDK runtime actually provides a lightweight and high-performance container, which can run both JavaScript and also the React server-side functions on edge servers. So let's say if you have very limited resources and very less computation power, then you can run these lightweight WebAssembly containers on edge applications and still be able to have performance functions being run very smoothly. And the Wasmage Quick JS, which Quick JS is basically very similar to how V8 functions, so it's a JavaScript engine, and the Wasmage Quick JS engine is able to actually render React app-based components on the server-side and then basically send that rendered HTML as a string to the browser. And it primarily supports both the static-side rendering and also the streaming rendering that is provided from the server-side. But the biggest question is that why should we use WebAssembly in the first place to implement server-side rendering? Because we already have such popular frameworks such as Next.js and also you can set it up manually with Node.js. There are primarily two different reasons I'd like to point out why WebAssembly is useful. Now, compared to the standard approach in which the V8 runs, it uses Node.js and a Linux-based environment. Wasmage and especially WebAssembly has a much smaller footprint in terms of the overall size and how quickly you can actually spin up a WebAssembly-based container. So in terms of performance, it's a lot more faster and especially when you're working with very limited resources on an Edge application or an Edge device. And this does help with more improved load times and performance gains, especially if you're running your applications on the Edge. And secondly, the Wasmage also provides isolation and protection because of how WebAssembly manages memory by providing a sandbox layer around whatever application that you're using with WebAssembly. So that means that the Wasmage implementation for server-side rendering is able to basically execute whatever code is being run in that sandbox environment that is the footfall for how WebAssembly actually works. And that's one of the biggest benefits of performance and both in terms of privacy as well.

So let's take a very quick glimpse into how you can actually enable server-side rendering with WebAssembly with a very simple Create React app that if you have already used React, you might have used the Create React app.

So the first thing is to basically install some of the dependencies. So this includes installing a programming language, which is Rust because we'll be basically compiling the Rust code into a Wasm, that is a WebAssembly executable. Then we'll also use the Wasi, Wasi is the WebAssembly system interface that allows you to basically interact with the server-side and the even networking components of your computer. And then we'll also install the Wasm Edge, which is the runtime for WebAssembly, the CLI for that, and the Quake.js Wasm Edge Toolkit as well. So we have provided those links on the slides. You can go through and install these separately.

Once you have done that, we'll just go ahead and install a very simple React app using the nbx-create-react-app. And now we actually come to the most important step, which is actually converting our code into server-side rendering. So primarily what we're going to be doing is that we're going to be using the Wasm Edge container, which will be able to run our server-side rendering code and be able to actually run our React JavaScript. So first, let's create a new directory which will be server, and within that, we'll create a new file, index.js. Now you can basically populate that content of that index.js by going to this file that I've created, and you'll find that code over here. It's primarily just going ahead and running a simple Node.js app, and this also is able to... It also has some components related to the WebAssembly, where we are basically rendering the actual server, basically the code of the React.js code inside of our Node back end. So I'd recommend you to go and check out this particular code base, and once you have done that, once you have added this particular code to your index.js file, then we'll proceed. But this will answer what's happening behind the scenes.

So basically the server that we are creating right now, which is the Node server, that is basically rendering the app component, and instead of sending this app component to the front end, what we are doing is instead we are sending that rendered HTML back to the browser. And primarily if we see that in standard cases with React, the React DOM server rendered string is used to typically render the app to an HTML string. And basically that's what we are sending to our browser in this case. So you're basically now, what we are doing is that the app's content is being injected into the dev element with an ID of the router. And now it's being sent back as an HTTP response to the web browser.

Now once you have created that index.html file, index.js file, we'll go ahead and build and deploy our application with the help of rollup.js. Again, we have provided a config file for rollup in case you are interested to use that. Again, that is providing the second gist, which is over here, which is the rollup.config.js. This is responsible for not only going ahead and building, but also deploying the server-side code that we have created inside of the index.js file. So once we go ahead and deploy our code with the help of rollup.js, the last few things that are left is first of all adding some of the dependent packages into our package.json file. These are mostly related to the rollup package that we have just installed in our previous slide. And the last thing that we have to do is updating our script section. So this is primarily used to be able to actually run the Wasmic server from the Wasmic CLI that will help us to first take our REST code and convert it into the WebAssembly bytecode. And then actually this will serve the purpose of also taking your QuickJS code, which also invokes the webpack and the configuration file.

And this will be help to solve our build output and so that do our front-end. And finally we'll just go ahead and run the following commands to first go ahead and build our application and then render the HTML string on the browser.

And finally, before we see what exactly takes place or what's the output, so let's examine what is the actual change in the app before and after we have actually enabled the service and rendering with the help of WebAssembly.

So previously, the HTML source was simply just putting out the template with the server-side rendering placeholders. But now, once the server-side function is running on the server and we are fetching our HTML, the generated HTML stream from the server and we are rendering it onto a browser, you can see that in the lower corner, what you can see is that now we also get this data react route. Now, this is what is being fetched from our server that is rendering our static files, and that's what is being rendered now on the browser. And that's how you will basically start to see it in live action, once you start rendering it.

So, what's more in terms of support for server-side rendering with WebAssembly? There's a current support for React 18, which is the latest version of React, and you can also actually create streaming applications because of the functionality that comes with WebAssembly. It allows you to actually create streaming applications because of the way in how WebAssembly actually loads itself on the browser. Instead of, let's say a static JSON file, the WebAssembly bytecode basically comes under a streaming fashion and gets loaded into the browser in a streaming fashion. So you can also create streaming applications, the one that we showed was a static application. With that, I'd like to conclude my talk. Thank you so much. In case you're interested to know more, you can connect with me on my Twitter, at TheCloudWeb. I keep posting a lot on WebAssembly and WebAssembly is a really futuristic technology and one of the technologies to look out for, especially today and in the next few years. Especially for both applications on the front-end browser, and also equally on the server side and in cloud applications. With that in mind, thank you so much and I hope that you enjoy React Advanced.