Building mixed-language appsAlan LudwigSenior Software Development Engineer4-100

The Windows Runtime makes it possible for you to write great apps using more than one language

The Windows Runtime (WinRT)

APIs A versionof Windows

Cross-language

infrastructure

What’s the best language foryour Windows 8 apps?The language you already knowThe language your component is already written inThe language that has access to the features you needThe language that provides the right performanceThe language of your choice

How do I do that?

When you write a Windows Runtime component,you can consume it in JavaScript, C#/VB, or C++

The same cross-language infrastructure that was used to create thousands of Windows Runtime APIs is available for you to write your own Windows Runtime APIs

Demo

Hybrid JavaScript and C++ Sample

Only where neededKeep it simpleAsync everywhere Mind your threads

How do I make it great?

Only where needed

Indirect function callsType conversion

Examples of type conversion

WinRT Type C++ JavaScript C# (.NET)

HSTRING Platform::String var (string) StringGUID GUID var (string) GUIDUInt32 uint32 var (double) uint32DateTime (FILETIME) var (date) DateTimeOffset

Keep it simple

Designing good Windows Runtime interfaces is similarto good OO design

Async everywhere

Use the async pattern for long running operationsThe language projections make this easy

Windows::Foundation::IAsyncOperation<uint32>^ DemoLib::GetCountAsync(){

auto async = concurrency::create_async(// your lambda here[this](){ return _count;});return async;

}

Async operation in C++

public Windows.Foundation.IAsyncOperation<UInt32> GetCountAsync(){return (Windows.Foundation.IAsyncOperation<UInt32>)Task<UInt32>.Run(

() => {return _count;} );

}

Async operation in C#

Mind your threads

Writing great components requires some basic knowledge of threading issues

UI is always thread affine

ThreadingUI

Thr

ead

Wor

ker T

hrea

d

Callasync API

Create task

Other work Update UI Continue

Do workCall

completion

How do I get back to the main thread?

Techniques to get back to the main threadDispatching via the UI elementDispatching via the core windowProxies and stubs

if (output->Dispatcher->HasThreadAccess()){ output->Text += "Count Changed (thread access)! Count is " + newCount.ToString() + "\n";}

Dispatching via the UI element

else{ output->Dispatcher->RunAsync( Windows::UI::Core::CoreDispatcherPriority::Normal, ref new Windows::UI::Core::DispatchedHandler( [this, newCount]() -> void { output->Text += "Count Changed (no thread access)! Count is " + newCount.ToString() + "\n";}));}

Dispatching via the UI element

Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync(

Windows::UI::Core::CoreDispatcherPriority::Normal,ref new Windows::UI::Core::DispatchedHandler(

[this,value](){CountChanged(this, value);}

));

Dispatching via the core window

The Windows Runtime will automatically move your calls back to the right thread if proxies and stubs are available

event Windows::Foundation::EventHandler<uint32>^ CountChanged;

event Windows::Foundation::TypedEventHandler<IDemoLib^, uint32>^ CountChanged;

EventHandler vs. TypedEventHandler

Create proxies and stubs for yourWindows Runtime components

Demo

Creating a Windows Runtime in-process component sample (C++/CX)

The same cross-language infrastructure that was used to create thousands of Windows Runtime APIs is available for you to write your own Windows Runtime APIs

Only where neededKeep it simpleAsync everywhere Mind your threads

How do I make it great?

• 10/30/2012 11:45 – B33 Baker – Bringing existing C++ code to Windows Store apps

• 11/1/2012 12:00 – B33 Hood – Gaming reimagined: Gaming case studies

Related Sessions

A list of sessions will be sent one week prior to the event

• Hybrid JavaScriptand C++ sample

• Creating a Windows Runtime in-process component sample (C++/CX)

Resources

Please submit session evals by using the Build Windows 8 appor at http://aka.ms/BuildSessions

• Develop: http://msdn.microsoft.com/en-US/windows/apps/br229512

• Design: http://design.windows.com/

• Samples: http://code.msdn.microsoft.com/windowsapps/Windows-8-Modern-Style-App-Samples

• Videos: http://channel9.msdn.com/Windows

Resources

Please submit session evals by using the Build Windows 8 appor at http://aka.ms/BuildSessions

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