1. Lessons learned designing the Windows Runtime
11/19/2018 4:12 AM
PLAT-876T
Lessons learned designing the Windows Runtime
Brent Rector
Senior Program Manager
Microsoft Corporation
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. Agenda Design considerations building a multi-language OS runtime
How these decisions affect coding in your preferred language
Apply this knowledge in your Metro style apps

3. Don’t make me write this again!
Agenda
Please RT
Don’t make me write this again!

4. Windows Runtime APIs Available to all programming languages
JavaScript
C#/VB
C++
Available to all programming languages
Requires a language neutral type system

5. Casing of APIs in multiple languages
Many languages use PascalCasing for names of types, methods, properties, and events
JavaScript has well established naming conventions
“Types” are PascalCased
Methods and Properties are camelCased
Events are all lowercase
Windows Runtime uses PascalCasing for types and members
JavaScript maps methods, properties and event names to its conventions
Causes oddities occasionally – UIElement -> uielement

6. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

7. Numeric types Behave differently in .NET/C++ compared to JavaScript
C++/.NET - Signed, Unsigned; 8, 16, 32, 64 bit int; 32, 64 bit float
JavaScript – double-precision 64-bit binary format IEEE 754 value
Windows Runtime – Same as C++/.NET without signed 8-bit integer
But…
Operating system uses 64-bit integers in some places
file sizes, position, etc.
JavaScript number can only represent 53 bits of precision

8. Numeric types ECMAScript (ECMA-262) Standard
Requires numbers treated as IEEE bit floating point values
JavaScript applications using the Chakra runtime cannot accurately determine the values of some 64-bit integers
But such values can be received from and passed back to WinRT APIs
Many (most) values will work fine
Use caution with 64 bit values whose absolute value is greater than 2^53 (9,007,199,254,740,992)

9. public ref class MyClass sealed { __int64 _largeNumber;
MyClass () { _largeNumber = ; }
property __int64 LargeNumber {
__int64 get() { return _largeNumber; }
void set(__int64 value) { _largeNumber = value; } }
bool CompareInt64(__int64 a, __int64 b) { return a == b; } };
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

10. var b = new MyLibrary.MyClass(); var val1 = b.largeNumber;
var isEqual = b.compareInt64(val1, val2); // true
val1 = val1 + 0;
isEqual = b.compareInt64(val1, val2); // false
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

11. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

12. Strings Immutable or mutable? Null
Immutable – JavaScript, .NET; Mutable – C++
Null
JavaScript: null is an object, string is a type
C++: std::string has no 'null' semantics
.NET System.String: reference type has a 'null' distinguished value
Windows Runtime: string's immutable, no null representation

13. public ref class MyClass sealed { Platform::String^ _myString;
MyClass () {_myString = nullptr; }
property Platform::String^ MyString {
Platform::String^ get() { return _myString; }
void set(Platform::String^ value) {
_myString = value; } } };
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

14. // What is the value of ‘s’? b.myString = null;
var s = b.myString;
// What is the value of ‘s’?
b.myString = null;
b.myString = "";
// What is the value of ‘s’
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

15. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

16. Structures Handled differently by languages As a result…
C++/CLR: Structures are value types, can contain all types
JavaScript: Has no structure construct but structures can be simulated
Windows Runtime supports structures, with restrictions on content
Can only contain numbers, strings or structures
Windows Runtime structures cannot contain pointers
Windows Runtime structures are value types
As a result…
Structure valued property behavior differs in languages

17. using namespace Windows::Foundation; public ref class MyClass sealed {
Rect _myBounds;
property Rect MyBounds {
Rect get() { return _myBounds; }
void set(Rect value) { _myBounds = value; } } };
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

18. b.myBounds = { x: 100, y: 200, width: 300, height: 400 } ;
b.myBounds.width = 42;
// What is the value of ‘width’?
b.myBounds = { x: b.myBounds.x,
y: b.myBounds.y,
width: 42,
height: b.myBounds.height };
var bounds = b.myBounds;
bounds.width = 42;
// What is the value of ‘b.myBounds.width’?
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

19. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

20. References & pointers
Target languages handle pointers and references differently
C++: All types can be passed by value or by reference
.NET: Objects are passed by reference, value types by value
JavaScript: Objects passed by reference, numbers passed by value
Windows Runtime: Objects (Interfaces) passed by reference, all other types passed by value
As a result…
Method parameters are [in] or [out], never [in, out]

21. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

22. Arrays Reference or value types? Windows Runtime
JavaScript, .NET, C++: Reference types
Windows Runtime
Arrays are value types so marshal by value
ONLY WHEN they are marshaled!

23. public ref class MyClass sealed {
void ArrayMethod (array<int>^ arr) { arr[0] = 42; }
void ArrayMethod2 (array<double>^ arr) { arr[0] = 42.0; } };
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

24. // What is the value of arr[0]? b.ArrayMethod2(arr);
var arr = { 1, 2, 3, 4, };
b.ArrayMethod (arr);
// What is the value of arr[0]?
b.ArrayMethod2(arr);
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

25. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

26. Events Event syntax differs across languages Be aware…
C++/CLR – Clients add events with += operator
JavaScript – Clients add events with either the addEventListener function or by setting the “on<eventname>” property on the object.
Be aware…
JavaScript event name casing is all lowercase
Assigning to the property implies one listener while addEventListener allows multiple listeners
Misspelling the event name in either case silently fails

27. public ref class SignaledEventArgs sealed {
public: SignaledEventArgs() { }; };
public delegate void SignaledEventHandler (
Platform::Object^ sender,
SignaledEventArgs args);
public ref class MyClass sealed {
event SignaledEventHandler^ Signaled;
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

28. var b = new MyLibrary.MyClass();
b.addEventListener ("Signaled", function () { … });
// What just happened?
b.addEventListener ("signaled", function () { … });
b.onSignaled = function () { … };
b.onsignaled = function () { … };
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

29. Events vs. delegates
Windows Runtime prefers events over delegate-typed properties
Both are (potentially) multi-cast
JavaScript nicely maps events to JavaScript event conventions
addEventListener (“eventname”, func)
oneventname property
Delegate properties are just that: properties
No addEvetListener form
Normal camelCasing of property name occurs: eventName

30. Windows Runtime types Basic Types INT32, UINT64
Most basic types supported
Strings
HSTRING
Avoids copying in multiple languages
Structures
struct Rect;
Can contain strings, but not interfaces
References
IInspectable
All classes, methods, properties and events are modeled using interfaces
Simple Arrays
INT32 []
For very basic collections
Events
event T^ Signaled;
Modeled as interface
Collections
IVector<T>
Type-generic interfaces

31. Collections Windows Runtime collections are relatively straightforward
Vectors – similar to array, projected with array syntax
Maps – key/value pairs, projected as dictionary to CLR apps
Surprise…
Because collection value accesses require a method call, they can be unexpected performance bottlenecks
Can use the GetMany method for bulk retrieval

32. Method overloading Two criteria used when handling overloads
Overload on number of params (arity)
JavaScript, .NET, C++ all distinguish methods by arity
Overload on parameter type
.NET, C++ all distinguish methods by type of parameters
JavaScript has a limited notion of type
Windows Runtime methods
Overload on arity but not on type

33. public ref class MyClass sealed {
Platform::String^ AnOverload (Platform::String^ a) {
return a; }
Platform::String^ AnOverload (Platform::String^ a,
Platform::String^ b) {
return a + b };
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

34. var str = b.AnOverload ("Hello"); // What just happened?
var str = b.anOverload ("Hello", " audience");
// What just happened?
var str = b.anOverload ("Hello", " audience", " at BUILD");
© 2010 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

35. Asynchronous APIs
Platform design goal that APIs cannot block the UI thread
Guidance: Anything taking > 50 ms should be asynchronous
Resulted in prevalent use of Async Pattern in platform
Established a naming pattern: <verb>[<noun>]Async
GetThumbnailAsync
Return value mapped to a promise for a future result
In .NET – await obj.GetThumbnailAsync()
In JavaScript – obj.GetThumbNailAsync().then (func);

36. Further reading and documentation
C++ language extension summary
The Windows Runtime
Windows Runtime Design

37. thank you Feedback and questions http://forums.dev.windows.com
Session feedback

38. 11/19/2018 4:12 AM
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
© 2011 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.