who will benefit from this talk topics what you’ll leave with asp.net developers, including web...

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Building IIS and ASP.NET apps with the power of async

Damian Edwards, Phil HaackProgram Managers, ASP.NETMicrosoft Corporation

SAC-804T

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Agenda slide

WHO WILL BENEFIT FROM THIS TALK

TOPICS WHAT YOU’LL LEAVE WITH

• ASP.NET developers, including Web Forms & MVC

• History of async programming in .NET

• How async works in ASP.NET

• Using async in ASP.NET apps

• How to use async programming in ASP.NET to increase scalability, improve page response time and implement long running requests

• The Task Parallel Library (TPL) and async/await support in in C# and .NET 4.5 makes programming async much easier than traditional APM

• ASP.NET 4.5, including the core framework, Web Forms and MVC, has great support for working with the TPL and async/await

A brief history of async programming in .NET

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Three async programming models

Asynchronous Programming

Model(APM)

Evented Asynchronous Programming

(EAP)

Task-based Asynchronous Programming

(TAP)

// .NET 1 model

file.BeginRead(buffer, 0, maxLength, asyncResult => {

int numBytesRead = file.EndRead(asyncResult); // Now do something with "buffer“

}, null);

Asynchronous Programming Model (APM)Asynchronous Programming Model (APM)

// .NET 2 model

webClient.DownloadStringCompleted += (sender, args) => {

string html = args.Result; // Now do something with "html"

};webClient.DownloadStringAsync(new Uri("http://example.com"));

Event-based Asynchronous Programming (EAP)

Task<string> htmlTask = webClient.DownloadStringTaskAsync(url);

htmlTask.ContinueWith(task => { string html = task.Result; // Async, C# 4});

string html = htmlTask.Result; // Sync (block until done)

string html = await htmlTask; // Async, C# 5

Task-based Asynchronous Programming (TAP)

public async Task<ViewResult> MyMethod(){ string myParam = "some value"; var data = await FetchSomeData(myParam); return View(data);} 2

1

public Task<ViewResult> MyMethod(){ string myParam = "some value"; return FetchSomeData(myParam).ContinueWith(task => { var data = task.Result; return View(data); });}

2

1

Before compilation

After compilation(conceptual)

How C# 5 “async” works

How async requests work in ASP.NET

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Traditional Web request handling“thread-per-request” a.k.a. “post office”

Thread pool

Requests

BusyBusy Busy Busy

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Asynchronous Web request handlinga.k.a. “restaurant”

Requests

Thread pool

Using async for benefit in ASP.NET apps. Easy as 1, 3, 2

So can I just use async everywhere in my ASP.NET app? No!

There are three (3) distinct scenarios where async in ASP.NET apps might be useful…

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Async IO in ASP.NET

demo

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Parallelizing work for faster request throughput

demo

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Handling long running, event driven requests

demo

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For more information

• TOOL-810T: Async made simple in Windows 8, with C# and Visual Basic

RELATED SESSIONS DOCUMENTATION & ARTICLES

• http://www.asp.net/vnext

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• Feedback and questions http://forums.dev.windows.com

• Session feedbackhttp://bldw.in/SessionFeedback

thank you

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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.