1. Maximizing code reuse between
Windows Phone 8 and Windows 8
Ken Cenerelli
@KenCenerelli
kencenerelli.wordpress.com

2. Agenda
• Part 1: Hardware Overview
• PlatformAPIs
• SharedCore
• Part 2: DevelopmentTechniques
• MVVM Project Structure
• PortableClass Libraries
• Shared XAML UI
• SharingCode with Partial Classes
• Wrap-up
• Next Steps, Resources & Q & A

3. Part 1: Hardware Overview
• We are on the path toWindows andWindows
Phone convergence
• Right nowWindows 8 andWindows Phone 8 have a
shared core but you cannot write once and run
everywhere (unlike iOS or Android)
• We can however leverage some existing
architecture similarities between the two

4. Some Key Differences
• It’s important to design for the platform
differences as well as similarities

5. Windows 8 Platform

6. Windows Phone 8 Platform

7. Shared APIs

8. What Shared Core Means
• OS components such as the kernel, networking,
graphics support, file system and multimedia are
the same on bothWindows 8 andWindows Phone
8
• Hardware manufacturers work with the same
driver model on both platforms
• Windows Phone gets the support for multi-core
and other hardware features that Windows has had
for years
• These solid, common foundations makes it easier
to extend the Windows platform into the future

9. What Shared Core Doesn’t Mean
• Windows 8 andWindows Phone 8 developers work
to exactly the same APIs
• (though you will see more commonality as new features
are introduced to both platforms in the future)

10. Part 2: Development Techniques
• Four examples of how you can approach code
reuse:
• MVVM project structure
• PortableClass Libraries
• Shared XAML UI
• Add As Link (Partial Classes)
• Accelerate your app development with these
methods
• Not all will work in every situation

11. MVVM - Overview
• MVVM is an architectural pattern:
• Relies on features XAML/C# provide

12. Why use MVVM?
• Loose coupling between UI and code
• Enables reusability
• Separation between UX designer & developer
• Increased testability

13. MVVM components
• Model
• Data or business logic
• Database,Web Services, File System, etc.
• View Model
• A specialization of the Model that theView uses
• Informs the view to update
• No UI code
• View
• Represents the user interface the user sees
• Should contain a minimal amount of code

14. MVVM for code reuse
• Create a separate UI for each platform to take
advantage of the different screen sizes
• MVVM by itself doesn’t help us for sharing code
across platforms – only on the same platform
• Use Portable Class Libraries to share models and
view models across platforms

15. Demo 1:
MVVM Project Setup

16. Portable Class Libraries -
Overview
• Portable Class Libraries have been available since
.NET Framework 4
• Portable assemblies can target multiple platforms,
includingWindows 7,Windows 8,Windows Phone,
Silverlight, and Xbox 360
• Only allowed to call APIs available across multiple
platforms
• Note: the Express versions ofVisual Studio 2012
don’t include a Portable Class Library project
template. It is available only inVisual Studio 2012
Pro or greater

17. Portable Class Libraries – What
To Share
• Any managed code you write, particularly app logic
• Do not share conditional compilation code (code forWP8 that
you want to implement differently forWindows 8)
• Instead, abstract away the platform-dependent code and share only
the portable, platform-independent code
• Windows Runtime APIs aren’t portable and can’t be used in a
PortableClass Library
• There is overlap in theWindows RuntimeAPIs that are supported on
WP8 andWindows 8. However, binary compatibility is not supported.
Your code has to be compiled for each platform
• Doesn’t use UI constructs
• AlthoughXAML forWP8 andWindows looks similar this code isn’t
portable

18. Portable Class Libraries & MVVM

19. Demo 2:
Portable Class Library

20. Shared XAML UI - Overview
• Isolate parts of your UI into user controls and
attempt to share those. Windows Phone 8 and
Windows 8 both support XAML user controls
• New controls take advantage of form factors
• Consider the Windows Phone when designing the
Windows 8 SnapView
• Limitations
• XAML onWindows Phone 8 and XAML onWindows 8 is not
binary compatible
• Namespace prefixes are different in XAML forWindows
Phone 8 and XAML forWindows 8

21. Shared XAML UI – What To
Share?

22. Demo 3:
Shared XAML UI

23. Sharing Code - Overview
• Change once, Change everywhere
• Approaches:
• Add as Link
• #if conditional blocks
• PartialClasses and Methods

24. Add As Link - Overview
• Use this technique for any code you’re able to
isolate that’s platform-independent and used in
both apps
• eg. User controls with no platform dependencies.
• This is particularly useful when you’re trying to
share code that uses aWindows Runtime API that
can’t be shared inside a Portable Class Library

25. #if Conditional Blocks - Overview
• Pros:
• Enable/Disable lines or chunks of code based on
compilation platform
• Existing compilation constants
• NETFX_CORE Windows 8
• WINDOWS_PHONE Windows Phone 8
• Useful for when there are subtle differences in syntax or
methods
• Cons:
• A downside is it can make code unreadable

26. Partial Classes - Overview
• Can put shared functionality in one code file and
platform specific code in additional code file
• Classes are marked as partial and compiled into a
single class
• Separates platform specific features
• Can use partial methods as a mechanism to
separate out platform specific logic

27. Demo 4:
Creating a Partial Class

28. Actions to continue your learning
• Build a project in bothWindows 8 and
Windows Phone 8
• Create a Portable Class Library to link
the two projects
• Choose one other development
technique to extend your code
between both projects

29. Resources for Attendees
• Channel 9: Building Apps for BothWindows 8
andWindows Phone 8 Jump Start
http://bit.ly/18dELOu
• Maximize code reuse betweenWindows Phone
8 and Windows 8 http://bit.ly/11TfzOl
• How to Make Portable Class LibrariesWork for
You http://bit.ly/116yIL4
• Channel 9: Create Cross-platformApps using
PortableClass Libraries http://bit.ly/1906wv8

30. Questions?
• Ken_Cenerelli@Outlook.com
• @KenCenerelli
• kencenerelli.wordpress.com