Service Workers arrive in iOS 11.3, bringing offline support to PWAs

Any technology is as good as it's adoption. The world is full of amazing technologies, which are not used and thus insignificant. Web Components have certainly had a hard time, and adoption has taken longer than expected by many. On the other hand PWAs are a sleeper hit and could eat the cake of App Stores.

Progressive Web Apps (PWAs) have been driven by Google and it's Android operating system and Chrome browser. However the PWA technologies are standards that anyone can adopt. Android has the technology, but updates are it's not alone in the market.

The other part of the duopoly of mobile operating systems is Apple's iOS. The company makes tons of money on the App Store and has not been keen to adopt the PWA model which allows bypassing this lucrative financial platform. In recent times Apple has made amendments towards the PWA models.

Full support for PWA specifications is expected only in the Fall release of iOS 12, but the intermediary update iOS 11.3 already brings a significant improvement for PWAs: Support for the Service Worker API. Service Workers are apps written in JavaScript that run even when you are not actively on the site.

Background tasks can be done by Service Workers, and they also have access to communications over HTTP. This may seem insignificant, but it allows the holy grail of web applications: Offline acccess. A PWA can be architected so that it retails a lot of the core functionality without a network connection.

This allows news apps, map apps and a lot of other interesting options previously only available to Native Android and iOS apps. Caching items for reading in the subway is a simple example that is trivial to implement in standard JavaScript. For more sophisticated caching try the Google Maps PWA.

In the beginning of 2108 it seems that PWAs are now set to bloom in late 2018 and early 2019. Time for vendors to start training staff and customers to see through the consultant sales bullshit.

-- Jani Tarvainen, 30/03/2018