Let’s start by copying app.js into our Vaadin app. Here is the code responsible for registering the service worker sw.js Instead of reading many references telling what to implement, a service worker, full screen, manifest etc, I will just copy working code and build based on it.Īt the bottom of the PWA template’s index.html, there is a reference to a Javascript fileĪnd by opening app.js we find that it’s responsible for registering and communicating with the service worker. The idea here is, I’ll decrease the learning curve. Yes, I mentioned it right, I will copy the code. Now we have a working reference to copy from. Related commit: Step 1 | Simple JS PWA 2) Building a PWA But still good enough to start with, and let’s make it our benchmark for a PWA with Java. Lighthouse gives it a score of 88% and we can easily see that there are a couple of small problems, and since we are testing locally, it’s not secure over HTTPS and thus not a perfect score. For example, if you follow the guide in this GitHub project generator-pwa, you will end up with a minimalistic web project that follows most of PWA specs. Luckily there are many templates in the open source web that give some guidance on how to start. Reverse engineering an already existing PWA is my favorite way to understand how it works. Related commit: Step 0 | Simple Vaadin App Unfortunately, at this point I get 22% compatibility and the report shows a lot of missing features in this simple app. Let’s start by looking at the state of a Java-based application today, by creating a very simple Vaadin application and then running the lighthouse report for it. To practically test that a web application follows PWA specs, there is a tool called lighthouse that generates a report showing how compatible you app is with the PWA specs. And this part is magically done with the help of the browser, if we only include a standard manifest file.ĭownload our free guide to the Future of Web Apps 1) Dismantling a PWA Update the service worker, what are the best practices to update the service worker when we add more functionalities to it? Specify files to be cached, this makes the app load faster in future visits, and makes a part of it available offline. We will take a quick look at an existing PWA and compare it with a normal Java app, to understand the major differences and what needs to be implemented.Īdd a service worker, It will help us implement modern browser functionalities, and other features that do not require a running web app, such as background sync, caching, and push notifications. Here are the steps summary:ĭismantling a PWA. In the following Devoxx presentation, Vaadin Expert Teemu Suo-Anttila and myself showed how it’s possible to create a PWA with a Java UI framework such as Vaadin:Įxtracting the content of that video here, but I’ll not use Spring this time, I’ll keep it as much generic as possible. Many concepts are the same for any Java web app. Follow the quick steps, and you get a PWA immediately. This is a perfect summary for you, saving a lot of time and hassle.I did some research and in this article, I’m going to present my findings. Using a PWA helps you improve your user experience. The number of users accessing web applications from a mobile device is bigger than those using desktop. If you want your web app to reach a bigger audience, while increasing the usability and experience for your users, then PWA is basically your way to achieve that. “It loads quickly, even on flaky networks, sends relevant push notifications, has an icon on the home screen, and loads as a top-level, full screen experience.” What is the big deal about Progressive Web Applications ( PWAs) and why are they trending nowadays? Here is one explanation by Google: Update 29-June-2018 : There are now more in depth resources about PWA, and example of integrating PWA with Vaadin Flow.
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