Nick's .NET Travels

Continually looking for the yellow brick road so I can catch me a wizard....

What’s a Progressive Web Applications (PWA) and Why does my website want to be one?

My last couple of posts (App or not to App and Cross-platform applications – PhoneGap/Cordova, Xamarin, PWAs and now Flutter) have been discussing different aspects of build applications. In particular in my previous post I discussed deployment models as being one dimension of applications. In this post I’m going to focus a bit more on the one of the hottest topics going around at the moment, Progressive Web Applications, or just PWA for short. If you’re new to this topic, I’d suggest a quick detour across to the Google developer site where they have an entire section dedicated to PWAs, and it’s a great starting point to understand the importance of PWAs and the experience that a good PWA should deliver.

Side note: I had to laugh when I first went to the PWA page on the Google developer site as it talks about “A new way to deliver amazing user experiences on the web”. This is really what happens when you let the marketing get out in front of technology. Unfortunately I’ve see this type of propaganda so many times (Flash, Silverlight, HTML5) that it actually makes me a bit nervous as I start to think about another learning curve.


One of the quickest ways to get past the marketing fluff is to click the PWA Checklist button in the top right corner of the PWA page. Here’s a list of some of the other useful links on the Google developer site in relation to PWAs:

- PWA Checklist

- Lighthouse

- PWA Summit videos (a bit dated but still a good place for building familiarity)

Now that I’ve assigned you a bit of reading, let’s talk about what all the fuss is about. After scanning through the PWA checklist it becomes very evident that there are a couple of key topics: security, offline, seo and notifications. Let’s break these down, with specific attention to why they’re all important aspects of a great application (not just a PWA).


Whilst not the first topic that comes up in regards to PWAs in the checklist it’s very evident that security first is still a key mantra when building the next generation of applications, which is made clear by the first item in the checklist which indicates that all content should be delivered across HTTPS.

In the context of application development there has been an increase flow towards the use of HTTPS (for example the release notes for iOS9 by Apple indicated that all new apps should use HTTPS). Without HTTPS it’s just too easy for any third party to intercept and read/modify the traffic to and from the application.


This is a biggie when it comes to PWAs and in fact you could argue that this is probably the most significant departure from traditional web development. The introduction of service workers that can intercept requests, cache and dynamical change request behaviour opens the world to building intelligent offline-enabled applications. However, from an offline-ready application development perspective the current thinking in this space seems relatively immature, with most of the priority being placed on caching the components that make up the application (ie the HTML, CSS, JS that make up the application), rather than offline data and synchronisation scenarios.


Optimising your application for search has been one of those things that every developer says they’re going to do but rarely do they do it, and seldom is it done well. In terms of application development, one of the challenges faced by developers is how to define a set of deep links that will resolve both on the web and in the app. In structuring an application, it should be possible to provide an external link to any part of the applications, and in an ideal world the the link can be shared via any method, whether it be a link on social media, or via private correspondence such as chat or email. The upshot is that by structuring an application this way, you’re already half way there to making it indexable – you just need to make sure that the web application can be statically crawled so that relevant sections will appear in search results.


Another aspect that tends to differentiate a good application is one where the user doesn’t have to keep on opening the application in order to see whether anything important has happened. All the native platforms, Windows, iOS and Android, have a rich push notification system that allow for interactivity and rich media in some cases. However, there is a disconnect as applications have to support multiple vendors that all support a slightly different push notification format. Notifications are important for a quality application as they help to keep the user informed about the things they care about most. The “Glance and Go” marketing campaign by Microsoft a number of years back for Windows Phone, whilst ultimately a failure (bye bye Windows Phone, we’ll miss you) it rang true in that notifications and badges are an extremely effective way of keeping users abreast of background activity within applications (either locally on the device, or remotely)

Hopefully from this breakdown you can see that PWAs, whilst one of the hottest topics today, is far from “a new way to deliver amazing user experiences,” since application developers have been doing this since before the release of the iPhone. I guess the big distinction with PWAs is the “on the web”…. as in “please developers, stop building web sites with a crappy user experience, and start building rich applications that delight the user”. Perhaps some day we’ll break the dependency on the request-response model that has for so long governed the design of web sites.

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