Learn how to take advantage of the new async/await operations to keep your applications responsive and avoid the performance bottlenecks. In comparison to how async code has been written with callbacks, the new way allows for cleaner more readable debug-able code. In this presentation, topics covered: Web Forms, MVC, EF6 some tooling.

1. DEVintersection
Session AS12
Building Asynchronous ASP.NET Applications

2. 2
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Agenda
 Quick History
 When is Async Useful
 Parallelism
 Tips & Resources

3. 3
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Async in .NET
.NET Framework 1.0 / 1.1
 1.0 – no async available
 1.1 – APM: Async Programming Model
IAsyncResult result = StartProcess(..);
// continue doing other work
// checking result.IsCompleted
int final = EndProcess(result);

4. 4
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Async in .NET
.NET Framework 2.0
 EAP: Event-base Async Pattern
ProcessCompleted += (sender, e) =>
{
// process the result here
};
AsyncProcessStart(…);

5. 5
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Async in .NET
.NET Framework 4.0
 TPL: Task Parallel Library

Task<int> t = ProcessAsync(…);
// process other work
// check t.Status, t.IsFaulted, etc.
int result = t.Result;

6. 6
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Async in .NET
.NET Framework 4.5
 async/await keywords
public async Task<int> Process() {
int result = await CompleteWork();
return result;
}

7. 7
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When to Async
When is it most useful?
 I/O


 Parallelism
 Long Running Tasks

8. 8
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Application Architecture
50 States
Web API
Web Forms
Application
Warnings db

9. Demo
WebForms

10. 10
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WebForms
Notes
 DO NOT async your Page_Load
 RegisterAsyncTask
 Set Async=“true” on your .aspx page to enable async pipeline

11. Demo
MVC / Web API

12. 12
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MVC / Web API
Notes
 Simple & Transparent
 Mark method as async, return Task<T>
 Use Entity Framework >= 6.1 for async methods



13. 13
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Parallelism
 Task.WhenAll
 Task.Run, ThreadPool.QueueUserWorkItem


14. Demo
Parallelism

15. 15
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Final Comments
 Avoid using Background Threads
 Do not use Task.Wait()

 Avoid Using Task.ContinueWith

 Parallel != Async


16. 16
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Resource & Links
 Hanselminutes Podcast – Everything .NET programmers know about
Asynchronous Programming is wrong.
http://hanselminutes.com/327/everything-net-programmers-know-
about-asynchronous-programming-is-wrong
 Using Asynchronous Methods in ASP.NET 4.5
http://www.asp.net/web-forms/tutorials/aspnet-45/using-asynchronous-
methods-in-aspnet-45
 Contact Information


17. Questions?
Thank you!
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