Sofia, Bulgaria | 9-10 October Asynchronous Programming for ASP.NET 2.0 Developers Julie Lerman The Data Farm Julie Lerman The Data Farm

Sofia, Bulgaria | 9-10 OctoberSofia, Bulgaria | 9-10 October

Asynchronous Programming for ASP.NET 2.0 Developers

Asynchronous Programming for ASP.NET 2.0 Developers

Julie Lerman

The Data Farm

Julie Lerman

The Data Farm

Sofia, Bulgaria | 9-10 October

About MeAbout Me

● .NET Mentor and Software Consultant

● 20+ years developing

● Microsoft .NET MVP, ASPInsider

● INETA Speaker

● Various publications & conferences● Blogs: thedatafarm.com/blog, blog.ziffdavis.com/devlife

● Founder and leader of Vermont .NET

● Former INETA Board Member

● INETA Speaker Committee

● Vermont Software Developer Alliance Board

● .NET Mentor and Software Consultant

● 20+ years developing

● Microsoft .NET MVP, ASPInsider

● INETA Speaker

● Various publications & conferences● Blogs: thedatafarm.com/blog, blog.ziffdavis.com/devlife

● Founder and leader of Vermont .NET

● Former INETA Board Member

● INETA Speaker Committee

● Vermont Software Developer Alliance Board


OverviewOverview

● Asynchronous Patterns in .NET

● New ASP.NET 2.0 Features

● Asynchronous Pages

● Asynchronous Web Services

● Asynchronous Tasks

● Asynchronous Data Access

● Client Side Callbacks ATLAS

● Post-Cache Substitution

● Asynchronous Patterns in .NET

● New ASP.NET 2.0 Features

● Asynchronous Pages

● Asynchronous Web Services

● Asynchronous Tasks

● Asynchronous Data Access

● Client Side Callbacks ATLAS

● Post-Cache Substitution


Asynchronous Patterns in .NETAsynchronous Patterns in .NET

● Pre- .NET 2.0● Delegates & Callbacks

● IAsyncResult

● WaitHandle

● .NET 2.0 Event Based Async Pattern● Plumbing is hidden

● Still need IAsyncResult in a few cases

● Implemented throughout .NET● In WinForms, In ASP.NET, In ADO.NET

● Pre- .NET 2.0● Delegates & Callbacks

● IAsyncResult

● WaitHandle

● .NET 2.0 Event Based Async Pattern● Plumbing is hidden

● Still need IAsyncResult in a few cases

● Implemented throughout .NET● In WinForms, In ASP.NET, In ADO.NET


Asynchronous MethodsAsynchronous Methods

● When calling out to external processes

● Use classes that can do so asynchronously

● Class must have

● Begin_Method(callback,state) as IAsyncResult

● End_Method(IAsyncResult)

● When calling out to external processes

● Use classes that can do so asynchronously

● Class must have

● Begin_Method(callback,state) as IAsyncResult

● End_Method(IAsyncResult)

Hello World

WS Proxy classBeginHelloWorld

EndHelloWorld

http://webservice


Thread B

Async Event PatternAsync Event Pattern

Application Process

Do long running process

Sub MethodthatCallsLRP

End Sub

Sub LRPCompleted_Event_Handler

End Sub

Thread A

Call BeginLRPDo other stuff

EndLRP(IAsyncResult)Do stuff with results sent back

Do other stuff

External Process(or separate thread in app process)


Synchronous PagesSynchronous PagesApplicationThread Pool

One thread pool per process

Default 25 threads per pool

Change with SetMaxThreads

??

??


Asynchronous PagesAsynchronous Pages● Purpose: Handle more requests

● Free up threads when external processes are called1. Begin page rendering

2. Drop thread while async process is running

Thread is now available to other requests

3. Grab new thread when process completes

4. Finish rendering

● Purpose: Handle more requests

● Free up threads when external processes are called1. Begin page rendering

2. Drop thread while async process is running

Thread is now available to other requests

3. Grab new thread when process completes

4. Finish rendering


Coding Async PagesCoding Async Pages

● Client Side

● <% @Page Async=True .... %>

● Server Side

● Page.AddOnPreRenderCompleteAsync(new BeginEventHandler(MyBeginMethod), new EndEventHandler (MyEndMethod) )

● Client Side

● <% @Page Async=True .... %>

● Server Side

● Page.AddOnPreRenderCompleteAsync(new BeginEventHandler(MyBeginMethod), new EndEventHandler (MyEndMethod) )


DemonstrationDemonstration

Asynchronous PagesAsynchronous Pages


Async Web ServicesAsync Web Services● IAsyncResult pattern (.NET 1.x & 2.0)

● ws.BeginmyMethod / ws.EndmyMethod● Manually manage context information● Coordination

● Use waitHandle to postpone page rendering● Can be combined with Asynchronous Pages

● Event Based Asynchronous Pattern (NET 2.0)● ws.myMethodAsync / ws.myMethodCompleted● HttpContext, Impersonation & culture carry● Coordination

● Render automatically continues when all services complete

● IAsyncResult pattern (.NET 1.x & 2.0)● ws.BeginmyMethod / ws.EndmyMethod● Manually manage context information● Coordination

● Use waitHandle to postpone page rendering● Can be combined with Asynchronous Pages

● Event Based Asynchronous Pattern (NET 2.0)● ws.myMethodAsync / ws.myMethodCompleted● HttpContext, Impersonation & culture carry● Coordination

● Render automatically continues when all services complete



Asynchronous Web ServicesAsynchronous Web Services


Asynchronous TasksAsynchronous Tasks● (Page) AddOnPreRenderCompleteAsync

● Limited to one asynchronous call

● Asynchronous Tasks● Make multiple (non web service) async calls

● Timeout setting

● Completion of multiple tasks is coordinated

● Code● PageAsyncTask + RegisterAsyncTask

● <@%Page AsyncTimeout =“##”>● Per task

● Defaults at 45 seconds

● (Page) AddOnPreRenderCompleteAsync● Limited to one asynchronous call

● Asynchronous Tasks● Make multiple (non web service) async calls

● Timeout setting

● Completion of multiple tasks is coordinated

● Code● PageAsyncTask + RegisterAsyncTask

● <@%Page AsyncTimeout =“##”>● Per task

● Defaults at 45 seconds



Asynchronous Tasks Asynchronous Tasks


Async Data BindingAsync Data Binding

● SqlCommand’s new async commands● BeginExecuteReader/EndExecuteReader● BeginExecuteXmlReader/EndExecuteXmlReader● BeginExecuteNonQuery/EndExecuteNonQuery

● Call a BeginExecute in MyBeginMethod ● Call an EndExecute in MyEndMethod

● Returns an IAsyncResult● Cast result back to data object

● DataBind in PreRenderComplete● “Asynchronous Processing=True” in

connection string

● SqlCommand’s new async commands● BeginExecuteReader/EndExecuteReader● BeginExecuteXmlReader/EndExecuteXmlReader● BeginExecuteNonQuery/EndExecuteNonQuery

● Call a BeginExecute in MyBeginMethod ● Call an EndExecute in MyEndMethod

● Returns an IAsyncResult● Cast result back to data object

● DataBind in PreRenderComplete● “Asynchronous Processing=True” in

connection string


Begin/End ExecuteBegin/End Execute

● Variety of overloads including callbacks, object state and command behavior

● Must call corresponding End to finish

● End will block SqlCommand until execution completes

● Use separate SqlCommand objects for each asynchronous call

● Variety of overloads including callbacks, object state and command behavior

● Must call corresponding End to finish

● End will block SqlCommand until execution completes

● Use separate SqlCommand objects for each asynchronous call



Asynchronous Data Binding Asynchronous Data Binding


Client-Side CallbacksClient-Side Callbacks

● Enables partial page postbacks

● Update controls from server

● Created before AJAX and ATLAS

● Complicated and hard to use

● Recommend AJAX or ATLAS instead

● Enables partial page postbacks

● Update controls from server

● Created before AJAX and ATLAS

● Complicated and hard to use

● Recommend AJAX or ATLAS instead


Client-Side CallbacksClient-Side Callbacks

● Calls server side process to update single web server control on a page

● Page does not post back

● Wired up in the code behind

● GetCallBackEventReference

● Ties server method, client script and control

● Four Overloads

● Calls server side process to update single web server control on a page

● Page does not post back

● Wired up in the code behind

● GetCallBackEventReference

● Ties server method, client script and control

● Four Overloads


Client-Side CallbacksClient-Side Callbacks● Avoid using viewstate on affected

control

● Browser basics● Internet Explorer 5+

● Uses Microsoft.XMLHttp

● Other Browsers● Uses XMLHttpRequest of the

browser’s DOM

● Great for simple scenarios● AJAX &Atlas for more complex use

● Avoid using viewstate on affected control

● Browser basics● Internet Explorer 5+

● Uses Microsoft.XMLHttp

● Other Browsers● Uses XMLHttpRequest of the

browser’s DOM

● Great for simple scenarios● AJAX &Atlas for more complex use


Client Side Callback Puzzle PiecesClient Side Callback Puzzle Pieces

[2] Create New Data FunctionImplements

RaiseCallbackEvent

[3] Return Data to Client FunctionImplements

GetCallbackResult

[5] RegisterClientScriptBlockscript that wires things up

on the client side

Server Side (code behind)

[4] GetCallbackEventReference wire up page, display script,

functions and affected control

Client Side

Control(if web server control,

avoid ViewState)

Display Update Scriptupdate control’s display

upon callback

Triggercalls script [5] registered

from the server side

[1] Implement ICallbackEventHandlerin code or declaratively



Partial Page Postback with ATLASPartial Page Postback with ATLAS


Post-Cache SubstitutionPost-Cache Substitution

● Update pieces page when rest of page is cached

● <asp:Substitution> control● Property: MethodName=“myStaticMethod”

● Static method returns a string to control

● Response.WriteSubstitution(....) ● Can be embedded in html <% %>

● Can be used elsewhere in code● Static methods not required when outside

page

● Controls are updated after cached page is rendered

● Update pieces page when rest of page is cached

● <asp:Substitution> control● Property: MethodName=“myStaticMethod”

● Static method returns a string to control

● Response.WriteSubstitution(....) ● Can be embedded in html <% %>

● Can be used elsewhere in code● Static methods not required when outside

page

● Controls are updated after cached page is rendered



Post-Cache SubstitutionPost-Cache Substitution


SummarySummary

● Build more efficient & responsive web apps with async ASP.NET 2.0

● Free up threads in the thread pool while page is pre-rendering

● Run multiple processes concurrently to speed up pre-rendering

● Leverage caching when only a bit of the page needs to be changed at postback

● Modify page parts without a full post-back

● Build more efficient & responsive web apps with async ASP.NET 2.0

● Free up threads in the thread pool while page is pre-rendering

● Run multiple processes concurrently to speed up pre-rendering

● Leverage caching when only a bit of the page needs to be changed at postback

● Modify page parts without a full post-back


Thank You!Thank You!● Contact Info

Julia Lerman

The Data Farm

[email protected]

www.thedatafarm.com

● Blog● www.thedatafarm.com/blog

● Contact InfoJulia Lerman

The Data Farm

[email protected]

www.thedatafarm.com

● Blog● www.thedatafarm.com/blog


Further ReadingFurther Reading

● Asynchronous Pages in ASP.NET 2.0, Jeff Prosise, MSDN Magazine Oct 2005

● Five Undiscovered Features on ASP.NET 2.0, Jeff Prosise Feb 2005

● Calling Web Services Asynchronously, Dan Wahlin, asp.netPRO, July 2006

● Fritz Onion Weblog: pluralsight.com/blogs/fritz● Asynchronous Web Parts, Fritz Onion, MSDN Mag

July 2006● MSDN VS2005 Docs: “Threads & Threading”● Asynchronous Command Execution in ADO.NET 2.0,

Pablo Castro, Microsoft : http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnvs05/html/async2.asp

● Asynchronous Pages in ASP.NET 2.0, Jeff Prosise, MSDN Magazine Oct 2005

● Five Undiscovered Features on ASP.NET 2.0, Jeff Prosise Feb 2005

● Calling Web Services Asynchronously, Dan Wahlin, asp.netPRO, July 2006

● Fritz Onion Weblog: pluralsight.com/blogs/fritz● Asynchronous Web Parts, Fritz Onion, MSDN Mag

July 2006● MSDN VS2005 Docs: “Threads & Threading”● Asynchronous Command Execution in ADO.NET 2.0,

Pablo Castro, Microsoft : http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnvs05/html/async2.asp


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Sofia, Bulgaria | 9-10 October Asynchronous Programming for ASP.NET 2.0 Developers Julie Lerman The Data Farm Julie Lerman The Data Farm