Microsoft programmer Kiril Seksenov has published Project Westminster in a nutshell, a short and readable guide to converting web-based apps into Universal Windows Apps that can run on a wide range of Windows 10 devices.
This is just one of the four bridges announced at the Build2015 conference, the others being bridges for Android and Apple iOS apps, and for traditional Windows programs.
What Microsoft calls "Hosted Web Apps" are apps that run mainly on the web, but are packaged and distributed via the Windows Store. This allows for apps that can be updated on the fly (web app publishers just update their servers) but can also exploit local features (such as Live Tiles and Cortana voice commands) and local content.
The main drawback with hosted web apps is that users may try to run them when they don't have an internet connection. However, Seksenov says: "Navigation to a local page can be done using the ms-appx:/// or ms-appx-web:/// protocols, allowing you to load html/css/JS from inside the package for an offline experience."
Seksenov says that Project Westminster is "agnostic" to developer preferences and workflows, as shown by his illustration (above). Programmers can use their favourite text editor, code repository and hosting site. Obviously, Microsoft might prefer it if they used Visual Studio and Azure, but they can use Atom, GitHub and Amazon AWS if they want.
Project Westminster is, as mentioned, just one of the four bridges announced at the Build2015 conference. (DevNet has a more comprehensive guide.) It enables developers to convert web apps and distribute them as Windows Store apps. Presumably it's named after Westminster Bridge in London.
Project Astoria is a bridge that enables developers to convert their Android apps into Universal Windows Store apps, as described at DevNet. Presumably it's named after the bridge across the Columbia River between Washington, Microsoft's home state, and Oregon.
Project Islandwood is a bridge that allows developers to use their Apple iOS code to create Universal Windows Store apps, by importing Objective-C into Visual Studio. Presumably it's named after the IslandWood Suspension Footbridge, which is also in the state of Washington.
Project Centennial is a bridge that will enable developers to convert traditional (or classic, or old fashioned) Windows programs developed for the Win32 API into Universal Windows Store apps, as demonstrated at Build2015 (video). There are several Centennial bridges. One connects Rock Island, Illinois and Davenport, Iowa, while another crosses the Panama Canal.
So, what's the idea?
Clearly, it would be better for users if all Windows programs were Windows Store apps. These are all available from a known and trusted location, they are easy to install and uninstall, they can easily be updated, they are much better controlled (under Windows Runtime), and they are sandboxed for security. They are, in fact, the Microsoft equivalent of Apple iPad apps, only inherently more flexible and potentially more powerful.
There are only two problems: getting developers to create them, and getting users to use them.
The four bridge projects aim to help with the first problem, by making it relatively simple to convert web apps, Android apps and iOS apps into Windows Store apps.
Getting people to use them is a bit trickier. Microsoft tried presenting users with a fait accompli in Windows 8, where the Start screen put Windows Store apps up front and put old fashioned Win32 apps further away. That didn't work out anything like as well as Microsoft probably hoped. It is, of course, almost impossible for an immature new system to compete with 25 years of established Windows software and user habits, as everyone should have recognized.
But giving users free upgrades to Windows 10 is a good ploy, with Microsoft aiming at around a billion users in three years. This would give developers a huge potential audience for Windows Store apps. Perhaps it just needs one of them to come up with a "killer app" for Windows Runtime to make the whole thing take off.
Sadly, Microsoft really didn't make the advantages of Windows Runtime apps clear to the general audience, which remains almost totally ignorant. As, it seems, is traditional IT, though that's still focused on Windows 7....