Examine how to better leverage the various technologies available to the developer to enable code reuse between Windows Phone 8 and Windows 8 Store apps. The slides will be broken into two parts with the first looking at what the two platforms share in terms of hardware and their ""shared core"". After this it will dig into some code to demonstrate how portable class libraries, shared XAML UI and the MVVM project structure can make a developer's life so much easier.

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