First, make sure you have the pre-requisites installed:
-
Node (https://nodejs.org/)
-
Java SDK 11 or higher (https://adoptopenjdk.net/)
We also recommend using either the Git Bash Shell or the Windows Subsystem for Linux if you’re on Windows.
Clone the micro-frontends-lab repo from github:
git clone https://github.com/kito99/micro-frontends-lab.git
Read the README file for an overview of the project (don’t follow the "Running" instructions quite yet). In this lab, we will build the Orchestrator and setup Express to serve the different micro frontends.
The Orchestrator is a simple bit of code that can route between different Web Components that are lazy-loaded. Each of these Web Components can be a separate micro frontend built using different technologies, but wrapped in a Web Component.
The Orchestrator is written using pure JavaScript and the Vaadin Router.
To begin, change into the
orchestrator folder.
This folder contains a README, a basic package.json, a shell index.htnml.
Let’s start by adding some links to index.html to support our micro frontends.
Place the follow code in the <body> of the file:
<div id="navigation">
<a href="/app-one">App One</a>
<a href="/app-two">App Two</a>
<a href="/app-three">App Three</a>
</div>
<div id="outlet">
</div>Here we’ve specified links for the different micro frontends, as well as an outlet where the router will render the selected app.
Let’s make things look a little better.
Add the following to the <head> of the document:
<style>
body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
font-size: 14px;
color: #333;
line-height: 24px;
}
#outlet {
margin: 20px;
border-radius: 4px;
border: 1px solid #eee;
background-color: #fafafa;
padding: 16px;
transition: all 0.2s ease-in-out;
}
#navigation > a {
padding: 5px;
color: #ffffff;
border-radius: 4px;
border: 1px solid #eee;
background-color: #007ad9;
text-decoration: none;
}
</style>In order to work with the Orchestrator, we need a static web server, preferably one that supports server-side includes. In the real world, this might be Ngnix, Apache, or a content-delivery network (like Akamai) or a caching proxy server (like Varnish or Squid). For our purposes, we’ll use Express.
Create a new file called server.js with the following code:
var express = require('express');
var app = express();
// Add routes to micro-frontends here
app.use('*', express.static('orchestrator', {index: "index.html"}));
app.listen(8000);This routes all pages to our main Orchestrator page.
Now, let’s run the server and view our page.
Run the command node server.js and point your browser to http://localhost:8000/.
You should see a simple page like the one below.
Clicking on a link should just reload the page.
Next, let’s add the Vaadin Router so that the Orchestrator can dynamically load different micro frontends.
Read the Vaadin Router docs for more information about the router.
Change to the orchestrator folder.
Inside index.html, add the following code at the end of the <body>:
<script type="module">
import {Router} from 'https://unpkg.com/@vaadin/router/dist/vaadin-router.min.js';
const outlet = document.getElementById('outlet');
const router = new Router(outlet);
router.setRoutes([
{
path: '/',
redirect: '/app-one'
}
]);
</script>First, note that we’re using native JavaScript modules. These are supported in all evergreen browsers. We’re loading the Vaadin Router from unpkg.com, but this could just as easily be installed locally via an npm package.
All this code does is wire up the <div> with the id "outlet" to the router, and map the root path to the micro frontend called app-one.
|
Note
|
In a real app, this might be encapsulated into a web component (or at least a separate JS file) and routes may be separated out into another file and loaded dynamically by the router. |
When you reload the page, it should work basically the same, except that when you click on a link, it won’t reload the page. Instead, you’ll see an error message from the Vaadin Router in the console complaining that the routes are not defined. We’ll handle that next.
Change to the app-one folder and follow the instructions in the README for building the app.
Once this is complete, there should be a bundle in the app-one/build folder ready to be loaded by the Orchestrator.
Change back to the orchestrator folder and add the new route to index.html inside of the array passed to router.setRoutes():
{
path: '/app-one',
component: 'x-app-one',
action: async () => {
await import('/app/one/app-one.js');
}
},Here, we’re mapping the route to a specific web component called x-app-one, which we are loading asynchronously from the location /app/one/app-one.js.
Once the component is loaded, its contents will be placed inside the outlet.
Next, we need to update server.js to handle the route /app/one/app-one.js.
Change to the root folder and add the following to server.js before the last route:
app.use('/app/one', express.static('app-one/build'));Now, let’s run the server and view our page.
Kill node (control-C), restart it with the command node server.js, and point your browser to http://localhost:8000/.
You should now see app-one embedded inside of the page:
Clicking on the other app links should display a blank outlet, as before.
Change to the app-two folder and follow the instructions in the README for building the app.
Once this is complete, there should be a bundle in the app-two/elements folder ready to be loaded by the Orchestrator.
Change back to the orchestrator folder and add the new route to index.html inside of the array passed to router.setRoutes():
{
path: '/app-two',
component: 'x-app-two',
action: async () => {
await import('/app/two/app-two.js');
}
},Here, we’re mapping the route to a specific web component called x-app-two, which we are loading asynchronously from the location /app/two/app-two.js.
Once the component is loaded, its contents will be placed inside the outlet.
Next, we need to update server.js to handle the route /app/two/app-two.js.
Change to the root folder and add the following to server.js before the last route:
app.use('/app/two', express.static('app-two/elements'));Now, let’s run the server and view our page.
Kill node (control-C), restart it with the command node server.js, and point your browser to http://localhost:8000/.
Click on the App Two link.
You should now see app-two embedded inside of the page:
The App One link should work just as before, and the App Three link should display a blank outlet.
Change to the app-three folder and follow the instructions in the README for building the app.
Once this is complete, there should be a bundle in the app-three/elements folder ready to be loaded by the Orchestrator.
|
Note
|
Don’t build |
Change back to the orchestrator folder and add the new route to index.html inside of the array passed to router.setRoutes():
{
path: '/app-three',
component: 'x-app-three',
action: async () => {
await import('/app/three/app-three.js');
}
}Here, we’re mapping the route to a specific web component called x-app-three, which we are loading asynchronously from the location /app/three/app-three.js.
Once the component is loaded, its contents will be placed inside the outlet.
Next, we need to update server.js to handle the route /app/three/app-three.js.
Change to the root folder and add the following to server.js before the last route:
app.use('/app/three', express.static('app-three/elements'));Now, let’s run the server and view our page.
Kill node (control-C), restart it with the command node server.js, and point your browser to http://localhost:8000/.
Click on the App Two link.
You should now see app-three embedded inside of the page:
All three links should work now, but noticeably App Three has no data. Let’s handle that next.
Unlike the other sample apps, App Three actually has a microservice back-end.
In order to launch it, change into the
app-three-server folder and follow the instructions in the README file.
