Development on Windows 8.1 Phone and Tablet

This is a follow up to my previous post (“Where are the Mobile Windows Devices?“) in which I gave my initial impressions of mobile windows devices.  As part of our assessment of these devices we also developed a few apps and this post details how that went.

Getting Started

Windows Phone 8.1 applications have to be developed on Windows 8.1.  I am using a Mac so I installed Windows 8.1 Enterprise Trial (90-day Free Trial) in a Parallels VM.  In order to run the Phone Emulator (which is also a VM and so I was running a VM in a VM), I had to enable Nested Virtualization in Parallels.

Development is done in Visual Studio, I don’t think you can use any other IDE. You can download a version of Visual Studio Express for free.

Finally, you’ll need a developer license to develop and test a Windows Store app before the Store can certify it. When you run Visual Studio for the first time, it prompts you to obtain a developer license. Read the license terms and then click I Accept if you agree. In the User Account Control (UAC) dialog box, click Yes if you want to continue. It was $19 for a developer license.


There are 2 distinct ways to develop applications on the Windows Platform.

Using the Windows Runtime (WinRT)

Applications build with WinRT are called “Windows Runtime apps”, again, there are 2 types of these:

  • “Windows Phone Store apps” are WinRT apps that run on the Windows Phone.
  • “Windows Store apps” that run on a Windows device such as a PC or tablet.

What’s really cool is that Visual Studio provide a universal Windows app template that lets you create a Windows Store app (for PCs, tablets, and laptops) and a Windows Phone Store app in the same project. When your work is finished, you can produce app packages for the Windows Store and Windows Phone Store with a single action to get your app out to customers on any Windows device. These applications can share a lot of their code, both business logic and presentation layer.

Even better, you can create Windows Runtime apps using the programming languages you’re most familiar with, like JavaScript, C#, Visual Basic, or C++. You can even write components in one language and use them in an app that’s written in another language.  Windows Runtime apps can use the Windows Runtime, a native API built into the operating system. This API is implemented in C++ and bindings (called “projections”) are created for  JavaScript, C#, Visual Basic, and C++ in a way that feels natural for each language.

Note that this is very different than the Phonegap/Cordova approach that also let you write apps in JavaScript. Universal Windows Apps do not run in a UIWebView/WebView, they are native applications for which (some of) the application logic gets run through the JavaScript engine. This means that they do not suffer from the challenges we face with Phonegap/Cordova (you can’t use cutting edge features, performance issues, etc.), yet you still get the benefits of using the language you are already familiar with.

This also allows you to use existing JavaScript libraries and CSS templates, no porting requires. You can even write one app use multiple languages, leveraging the dynamic nature of JavaScript for app logic while leveraging languages like C# and C++ for more computationally intensive tasks.

Traditional (Not using the WinRT)

Applications that do not use the WinRT are called Windows desktop app and are executables or browser plug-ins that runs in the Windows desktop environment. These apps are typically written in Win32 and COM, .NET, WPF, or Direct3D APIs. There are also Windows Phone Silverlight apps which are Windows Phone apps that uses the Windows Phone Silverlight UI Framework instead of the Windows Runtime and can be sold in the Windows Phone Store.


To deploy to my device I had to first “developer unlock” my phone (instructions).

Deployment is a breeze from Visual Studio, just hook up your phone, select your device and hit deploy. The application gets saved to your phone and it opens. It appears in the apps list like all other apps.  You can also “side-load” applications to other windows machines for testing purpose, just package your application up in Visual Studio, put it on a USB stick, stick it in the other Tablet/PC and run the install script created by the packaging process.

I created 2 simple application, one was a C# Universal Application and one was a JavaScript/CSS3/HTML5 Universal Application. I was able to deploy and run both on a Tablet, Desktop and Phone without any problem. They were very simple applications but I could not see any performance difference between the C# application and the JS application.

Additional Findings

For best User Experience when developing Universal Apps using JS/HTML5/CSS3 you should develop Single Page Applications (SPA).  This ensures there are no weird “page loads” in the middle of your app running.  Users will not expect this from their application, remember, these are universal apps and could be run by a user on his desktop.

State can be easily shared between devices by automatically roaming app settings and state, along with Windows settings, between trusted devices on which the user is logged in with the same Microsoft account.

Applications on the Windows App Store come with build in crashanalytics: This is one of the valuable services you get in exchange for your annual registration with the Store, no need to build it yourself.

As a JavaScript developer myself I am extremely excited by the fact that I can develop native applications on the Windows Platform using tools that I am already familiar with.  Furthermore, with Windows 10 it seems that Microsoft is doubling down on Universal Apps and with that OS Upgrade, my JavaScript apps can soon also be deployed to the HoloLens, Surface Hub, and IoT devices like the Raspberry Pi 2!

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