Progressive web apps (PWAs) are applications that use emerging web browser API to create a native app-like experience for the users. PWAs are gaining popularity these days for their seamless compatibility & amazing features. These have turned out to be very user-friendly as compared to other mobile app technologies and is leveraged by top brands like Pinterest, Trivago, Alibaba & many more.This blog post will cover everything you need to know about PWAs.
Predecessors
Steve Jobs, one of the founders of Apple, during the first launch of the iPhone in 2007, announced that web apps that were developed in HTML files using AJAX architecture would be the standard format for all iPhone apps. It will be integrated into the device using the Safari engine.
Dynamic web pages used web technologies to develop user-friendly web applications. The web designs proposed screen-sized flexibility made PWA development more accessible and easy for the users. Further enhancements to HTML, CSS, and JavaScript allowed web applications to incorporate greater levels of interactivity with the users
Mozilla released Firefox OS in the year 2013. It was developed as an open-source operating system for running web apps on mobile devices. The main operating system of Firefox was based on the Gecko rendering engine with a user interface called Gaia. The development of Firefox OS was last done in 2016 and further development was stopped until then.
The term "progressive web apps” was first coined by Frances Berriman and Google Chrome engineer Alex Russell in the year 1915, to describe apps working on new features supported by modern browsers and technologies, including service workers and app manifests. Google launched various programs for promoting PWA development for the Android systems. Microsoft Edge, Firefox, and Apple safari later accepted progressive web apps to be included in all their major systems from 2017 onwards.
Progressive web application or PWA is an application software developed through various programming languages such as HTML, CSS, and JavaScript. It is designed in such a way so that it can work on any platform that operates on a standards-compliant browser, including both desktop, laptops, and mobile phones.
Since the progressive app is a type of webpage or website, they do not require separate distribution. The web application can be published online if they satisfy the basic installability requirements. Users can easily add that website to their home screen. The developers of progressive web applications don't need to publish them in dedicated app stores such as the apple store.
Installability Criteria for Progressive Web Applications
1. Progressive web applications must be served or distributed via HTTPS to ensure the privacy, security, and authenticity of the content.
2. It must use service workers to develop programmable caches. Unlike typical HTTP web cache, which caches the content only after its first use and then heavily rely on its program integrals before publishing it as no longer needed, programmable caches can fetch content in advance prior it's being used for the first time and discards it immediately when it is no longer needed.
3.The manifest should have these key properties:‘name’,’short_name’,’start_url’,’ display’. Due to this manifest, progressive web apps can be easily shared via a URL, and they do not require any complex installation. They can be listed in third-party app stores.
Manifests
An application manifest is a W3C specification designed just to provide the developers with a centralized space to put metadata associated with a web application consisting of:
1.The name of the web application
2.Links to the web app icons or image objects
3.The preferred URL to launch or open the web app
4.The web app configuration data
5.Default orientation of the web app
6.The option to set the display mode, e.g. full screen
Characteristics of PWAs
Progressive web apps are designed in such a way that they can work on any browser that is the standard. The main goal is to aid developers to build cross-platform apps more easily and in less time.
Some progressive web apps use an architectural model called App Shell Model. The main advantage of the App shell model is that developers can store the basic user interface called ‘shells’ of the responsive web design web application in the browser's offline cache. This can improve loading time, by providing an initial static frame to the page. Here are some key characteristics of PWAs.
1.Data storage and web storage: Execution contexts of PWAs get unloaded or overloaded whenever possible, so progressive web apps need to develop long term internal states so the data gets allocated in the memory permanently and can be retrieved any time.
Web Storage is an API of W3C standards that enables key-value storage in modern browsers. It consists of two storage, session-Storage (that enables session-only storage that gets wiped upon browser session end) and local-Storage (that enables storage that persists across sessions)
2.iOS Support: Apple Safari implements manifest according to its policies and criteria, while most of the PWA metadata can be defined via iOS-specific meta tags. Specific tags allow developers to establish their web applications to the next level. It enhances full-screen display, defines icons and splash screens, and specifies a name for the application.
3.App Store: A PWA never requires individual distributions. Developers or users are not forced to install the web apps via digital distribution systems like Apple App Store, Google Play, Microsoft Store, or Samsung Galaxy Store. The major app stores support PWAs, allowing them to be distributed and promoted through their respective app stores such as Google Play, Microsoft Store, and Samsung Galaxy Store support PWAs or progressive web applications, but Apple Store does not due to their privacy policy. Microsoft Store publishes various progressive web apps even without its author’s request which satisfies their criteria.
PWAs are the present & future of mobile app development. And with the number of increasing smartphone users, businesses are choosing this technology to reach out to global audiences present on different devices. PWAs give businesses an edge with their amazing features & are definitely here to stay.
