WinRT demystified

http://tirania.org/blog/archive/2011/Sep-15.html

by friism • 15 years ago

152 45 15 years ago

batina• 15 years ago

Great explanation. Can't wait to finish downloading Windows 8 to start playing with it.

Asynchronous API that will really make a difference for the end user, right? There won't be any more waiting for UI to unfreeze :)

sgt• 15 years ago

I agree. This API will be a paradigm change for Microsoft. I particularly liked Miguel's explanation as well. In fact, it's the only one I found that really explained it in programmer's terms. Now, how soon will there be a Mono implementation fo this I wonder?

IvoDankolov3• 15 years ago

Not just for the user - calling asynchronous tasks using the new C# or VB keywords is so mind-bogglingly easy that you'll just have no excuse not to do it when writing apps.

Even the use cases that are not covered by the two keywords, like fetching a whole bunch of stuff together or issuing a lot of requests and having the data trickle in as they are completed one by one are handled easily with the Task API, to the point where you have WhenAny and WhenAll methods and you just do "await Task.WhenAll(tasks)".

d4nt• 15 years ago

  When you use C# and VB, you are using the full .NET 
  framework. But they have chosen to expose a smaller 
  subset of the API to developers to push the new vision 
  for Windows 8.

For me, this is a really interesting point that this article doesn't fully get. When you use WinRT you might be using the C# compiler, CLR runtime and .NET string & collection classes, but there are huge sections of the .NET BCL that now look like a lame duck. WinRT is the new way to do XML, JSON, HTTP, networking, security, globalisation, threading, printing... (more here: http://msdn.microsoft.com/en-us/library/windows/apps/br21137...)

You can still use the full .NET class library when doing ASP.NET, but who wants to use different JSON classes for App development vs. Web development? Won't the WinRT version gradually become the preferred way of doing JSON in both environments, with the .NET BCL existing to fill in the server side only gaps?

smhinsey• 15 years ago

This is a really interesting question. I did some quick skimming over the docs there and even where there is conceptual overlap, the BCL wins in terms of feature breadth. It would be challenging to replace it, I think.

My suspicion is that .NET 5 will merge the two.

drivebyacct22• 15 years ago

The article says WinRT is not accessible from non metro apps.

kbd• 15 years ago

It's amazing to see just how much Apple is driving the industry. Microsoft is making an app store, completely rethought their UI and programming model for mobile devices...

JoeAltmaier• 15 years ago

Um, it sounds like 'mobile' is driving the industry. Apple is a player too, just like everybody else.

shimonamit• 15 years ago

Don't forget that Apple invented the new 'mobile' as we now know it - hardware, UX, app store etc. Everybody else is following.

crenshaw• 15 years ago

Isn't it amazing to see how much MS is driving the industry. Apple is doing a smartphone, TV focused UI, tablet, and cloud services. :-)

drivebyacct22• 15 years ago

I'd mention the 10+ year old Apt or Android or other things, but its still not terribly relevant.

HardyLeung• 15 years ago

Wow, very well written. Thanks Miguel!

beagle39• 15 years ago

Does anyone know if it will have a Sound API? .NET still doesn't. Neither does it have usable Direct{3D,Sound,X} binding.

jbk3• 15 years ago

Use WASAPI: http://msdn.microsoft.com/en-us/library/dd371455%28v=vs.85%2...

beagle39• 15 years ago

Google "wasapi c# example", go on, google it.

gecko2• 15 years ago

I'm not a DirectX developer, but it looks to me like I've got huge swaths of DirectSound directly available from C#. I can check something specific, if you'd like.

beagle39• 15 years ago

I'm developing an app for surveillance that talks to multiple IP cameras and microphones. We made the unfortunate choice of C# early on.

- no normal RTSP support. Ok, I used libav (working hard to wrap it, cause it's a well written C library, but not trivial to use from C#)

- I get h264 frames that I need to look at before decoding. No way to give compressed h264 frames to WPF to decode. (So I use libav again). SilverLight actually does have MediaStreamSource -- but this is not a SilverLight app.

- Ok, so let's try to use the hardware decoder when it's there. libav supports it, yay! What about WPF? Well, no. You have to use Direct3D (?) to get a surface to draw on. With no way to do this from C# (Interop fails badly according to a DirectShow+Direct3D MVP I consulted). I give up, and use libav's software decoder.

- Ok, I have a bitmap, I want to blit it quickly to the screen - WTF? The only way to do it is use a Shared Memory section (interop again) to create a bitmapsource; then update the underlying memory.

- Except memory runs out after about 20 seconds (~400 frames) of .Invalidate() calls. WTF? Turns out it's a known bug introduced in v4 (wasn't there in v3.5). No fix yet. Just call GC.Collect() after every invalidate. Yay for "automatic" garbage collection!

- Ok, so now we have got a reasonable video. What about sound? Everyone with experience I know says "use NSound" (which is interop again). I opt for interopping with winmm, which I have experience from the C++ side.

- Now, to wrap it all together, I need a millisecond-precision timer. Sorry, no go in .net; Winmm's "timeBeginPeriod" to the rescue! but .net's Dispatcher still triggers my code every 15ms. WTF? I would be happier with a 100us timer, which windows doesn't even provide, but I can't get less than 15000us!

I'm so sorry we chose .NET; it seems to cater well to CRUD type applications, but it is so inadequate for everything I tried to do with it, that it's not even funny.

maximilianburke• 15 years ago

You can use SlimDX if you need DirectX bindings, but currently the only supported method provided by Microsoft is with XNA.

synacksynack• 15 years ago

There seems to be a lot available for multimedia with C++.

http://msdn.microsoft.com/en-us/library/windows/apps/hh45275...

beagle39• 15 years ago

Might be useful, but I'm not holding my breath. I have to deliver in a couple of months.

josteink• 15 years ago

Completely unrelated, but if the article didn't overwhelm you, the linked video session really is worth checking out.

http://channel9.msdn.com/Events/BUILD/BUILD2011/BPS-1004

It shows just how much attention to detail Microsoft has put into the UX design of Metro and Windows 8. Can't wait to see the finished product.

IvoDankolov3• 15 years ago

Aye, as someone who didn't have many expectations (though I didn't expect Windows 8 to be a failure either, I'm not one to rage about changing the sacred desktop look), throughout the keynote and this video they managed to pleasantly surprise me many times.

The design aside (which is an entire topic on its own), some of the functionality decisions like contracts just make you wonder why the sodding hell didn't we have these sooner. I mean there's the half-baked drag and drop handler than no one actually bothers to implement even when it makes absolute sense to do so, and that's it. Being able to pull things out of a web service from the file picker, on the other hand, just makes me go "I want this yesterday."

krig2• 15 years ago

The following is the full source code for a component that adds 2:

  public sealed class AddTwo {
    public int Add (int a, int b)
    {
       return a + b;
    }
  
    public async IAsyncOperation SubAsync (int a, int b)
    {
       return a - await (CountEveryBitByHand (b));
    }
  }

Sorry for being an idiot here, but.. does this example make any sense to anyone else? There's a method that adds two numbers, but the async operation is SubAsync which subtracts something passed through CountEveryBitByHand from a... passed through something called await? Is this obvious to other people? Does he mean that any sealed class automatically becomes a component, so the AddTwo part is just the Add method? What does "a component that adds 2" mean anyway?

Is it a joke and I'm not getting it?

EvilTrout• 15 years ago

I suspect the second method is just an example of how you could make an asynchronous operation that performs a subtracting of two numbers, after a method (CountEveryBitByHand) is completed.

To keep it simple they should have left out the second method.

Unless I'm incredibly wrong!

jinushaun• 15 years ago

Miguel is a pretty l33t developer, so he glosses over a lot of the details.

I suspect that code is contained in a class library project. Aka, generates a DLL. So no, not all sealed classes will be components.

The second method is there to illustrate what asynchronous programming will look like in C# 5. Native support for async is THE big feature in C# 5. The "await" allows you to call slow blocking code without a thorny nest of callbacks. There's some magic behind await. You can find out more on Google. Miguel could've definitely left out the SubAsync method in this example for clarity.

A component that adds 2 means a DLL that exposes the methods Add and SubAsync. In WinRT, you can code libraries in C# and use them in C++. Or Javascript.

krig2• 15 years ago

Aha, that almost makes sense. You're saying "add 2" might mean a component that exposes two methods. Not sure what exactly he is demonstrating there, actually. I mean, here's a DLL written in C that exposes the same two methods (although not asynchronous):

  int Add(int a, int b) { return a + b; }
  int Sub(int a, int b) { return a - CountEveryBitByHand(b); }

So, I guess the example is just to show the async stuff, really.

joeshaw• 15 years ago

CountEveryBitByHand() is a function which returns a promise. (I don't know if that's what they call it in C# 5.)

The await keyword is a new one in C# 5 which halts execution until the promise is fulfilled. Then execution is resumed from that point, and the expression can be evaluated and the function returns.

It's similar to how inlineCallbacks in Twisted work, if you're familiar with those.

davidpadbury• 15 years ago

(I don't know if that's what they call it in C# 5.)

Tasks - http://msdn.microsoft.com/en-us/library/system.threading.tas....

rwolf2• 15 years ago

    and Javascript uses promises and "then ()".

What is "then ()"? Have they created their own wacky fork of Javascript? Javascript already handles asynchronous programming (feel free to argue that is doesn't do it "right" or even "well"), so why extend the language?

kevingadd• 15 years ago

It's a method with a signature like this:

    promise.then(callback)

so:

    var p = doSomethingAsync();
    p.then(function () { alert("hello"); })

rwolf2• 15 years ago

I saw all of those extra spaces around "then" in the article and assumed the worst. Thanks for clearing that up for me!

nxn• 15 years ago

I'm assuming they only chose to use this pattern for the purpose of keeping function/method signatures as uniform across the languages as possible? I can't see another advantage to this in JS. Seems like all it's doing is wrapping the call to the actual async operation within the 'then' function, and then probably using the callback as the last argument or storing it somewhere where it will be accessible to the async operation right before it returns.

IvoDankolov3• 15 years ago

From what I can tell it's just a convention in their APIs for binding continuations. You do some WinRT asynchronous call and pass a func to the then method to run when it completes. Nothing more than a onFinished event.

No changes to async programming at all, events and continuations as always.

chucknthem• 15 years ago

"You might be thinking that you can use some trick (referencing the GAC library instead of the compiler reference or using reflection to get to private APIs, or P/Invoking into Win32). But all of those uses will be caught by AppStore review application"

I'm curious to know, how will the review application be able to catch your use of the private API through reflection? It seems like a pretty hard problem that could be a big security risk if done incorrectly.

beagle39• 15 years ago

I don't know, but it just _might_ be time for Microsoft to do jail-style security, in which you can't actually reflect from libraries you have no permission to.

WinRT demystified

Related Stories