Understanding ASP.NET Under The Covers

Nicholas GoossensR&D LeadOpen Box SoftwareSession Code: WUX302

How does it work?

Classic ASP

ASP.NetAuthentication

Page Lifecycle

AJAX Controls

.aspx

.ashx

Handlers

User Controls

Custom Controls

Browser Targeting

Doc Types

Services

Master Pages

Client Script

Request

Response

Parsing

Agenda

ASP from Then till NowBuzzwordsRequest-to-Response WalkthroughASP.Net ExtrasSummary

Classic ASP

Interpreted languageIncluded embedded scripting code mixed into HTMLLimited to VBScriptRan in the same process as IISInherently not scalable (needed MTS)

ASP.Net Beginnings

Designed by Scott Guthrie & Mark AndersOriginally known as XSP

Not .NET-related – Java based !Became ASP+ with the design of the CLR

Rewritten in C#Renamed when .NET branding introduced

What is ASP.Net

A framework for developing and delivering information & applications on the web.Known primarily as a page framework.A complete Request/Response management system.Can handle and respond to all sorts of requests on the Internet (or an Intranet).

Characteristics of ASP.NET

Runs under its own worker process.No longer tied to IIS.Code execution managed by CLR.Code-Behind model allows code separation.Includes state handling facilities.Provides caching functionality.

Commonly Used Terms

RequestHTTP query from client to server

Response Data stream send from server to client

ASP.Net PipelineA series of extensible functionality points which continue the process of a request in order to eventually obtain a response.

Page LifecycleAnother series of functionality points that form the process of converting an ASPX page to HTML output.The entire page lifecycle occurs between two pipeline points.

Request-to-ResponseBlack Box

demo

Request-to-Response

Desktop Browser

http://www.microsoft.com/default.aspx

Black Box - Web Server (IIS)

Convert ASPX to HTML

Rendered HTML

Getting to .NET

http.sys

aspnet_isapi.dll (unmanaged)

Web Server (IIS)

Worker Process (Per App Pool)

App Domain (Per VD)

ISAPIRuntime (Managed)

http://www.asp.net/

Pipeline Kicked Off

ASP.NET Takes OverHttpRuntime.ProcessRequest

HttpContext created.This serves as an entry point into the

request, response, and other accessible variables.

An HttpApplication instance is created.

HttpApplication

Init method starts pipeline processing.

Request Initializationdemo

ASP.Net Pipeline

HttpApplication BuildStepsEvent ProcessingChecks Hooks from Global.asaxChecks hooks from HTTP Modules

URL-RewritingAuthentication - HttpContext.Current.UserCachingKick off Page Lifecycle

HttpApplication

BeginRequest

AuthenticateRequest / Post

AuthorizeRequest / Post

ResolveRequestCache / Post

MapRequestHandler / Post

AcquireRequestState / Post

PreRequestHandlerExecute / Post

ReleaseRequestState / Post

UpdateRequestCache / Post

LogRequest / Post

EndRequest

PreSendRequestHeaders

PreSendRequestContent

ASP.Net Pipelinedemo

HTTP Modules

Classes that implement IHttpModule.

MyModule : IHttpModule

ASP.NET HTTP Modules of Interest

WindowsAuthenticationModuleFormsAuthenticationModuleUrlAuthenticationModuleFileAuthorizationModuleServiceModelSessionStateModuleOutputCacheModule

ASP.Net Modulesdemo

Where the magic happensHttpApplication

BeginRequest

AuthenticateRequest / Post

AuthorizeRequest / Post

ResolveRequestCache / Post

MapRequestHandler / Post

AcquireRequestState / Post

PreRequestHandlerExecute / Post

ReleaseRequestState / Post

UpdateRequestCache / Post

LogRequest / Post

EndRequest

PreSendRequestHeaders

PreSendRequestContent

PreRequestHandlerExecute / Post

HTTP Handlers

Classes that implement IHttpHandler.

MyHandler : IHttpHandler

HTTP Handler Factories

Can also implement IHttpHandlerFactory.

MyHandlerFactory : IHttpHandlerFactory

Handler Installation

Any level in the Config chain

Handler factory that returns and executes the handler that will convert an ASPX page to HTML

output.

Handlersdemo

The PageHandlerFactory Class

Implements IHttpHandlerFactory.GetHandler method returns an IHttpHandler in the form of System.Web.UI.Page-derived class hierarchy.

Page class implements IHttpHandler.Page class inherits from Control.Control contains events/methods for the “Page Event Lifecycle”.PageHandlerFactory creates a class structure out of your request.

Anonymous ClassCreated from ASPX content

Determines language to be

used to generate page-gen class.

Specifies the partial class to

serve as the code-behind.

Optional:Name of the code-

file for Visual Studio.

Anonymous ClassCreated from ASPX content

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

Converted to instances of System.Web.UI.LiteralControl

that are added to the control tree of this class.Remember, this class will ultimately inherit from

System.Web.UI.Control

Anonymous ClassCreated from ASPX content

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

Program code directly added to generated class.

Anonymous ClassCreated from ASPX content

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

Converted to instances of the corresponding server control class for each of these control tags, that will be added to the control tree

of this class.The Form control instance is placed directly

in the control tree of the class being created; while the TextBox and Label

controls are added to the control tree of the Form control.

Anonymous ClassCreated from ASPX content

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

__PAGE System.Web.UI.Page

ctrl0 System.Web.UI.LiteralControl

Function Code

ctrl1 System.Web.UI.LiteralControl

form1 System.Web.UI.HtmlControls.HtmlForm

ctrl2 System.Web.UI.LiteralControl

TextBox1 System.Web.UI.WebControls.TextBox

ctrl3 System.Web.UI.LiteralControl

Label1 System.Web.UI.WebControls.Label

ctrl4 System.Web.UI.LiteralControl

ctrl5 System.Web.UI.LiteralControl

Remember: this class “ultimately” inherits from System.Web.UI.Page

Control IDs

Anonymous ClassCreated from ASPX content

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

LiteralControl

Page Class Generation

Anonymous Class Creationdemo

Page (Control) LifecyclePreInitInitInitCompleteCreateChildControls (IsPostBack)LoadViewState/LoadControlStateIPostBackDataHandler.LoadPostDataPreLoadLoadIPostBackDataHandler.RaisePostBackChangedEventIPostBackEventHandler.RaisePostBackEventLoadCompleteCreateChildControls (!IsPostBack)PreRenderDataBindPreRenderCompleteSaveViewState/SaveControlStateRenderUnload

Complete List

Control Rendering

Activated through the Control class’ Render method.Each control is designed to output something to the response buffer.Most controls output HTML.Some controls contain others in their tree.Control rendering involves recursively rendering child controls.Controls don’t need to output anything

ScriptManager

Getting a Response

“Rendering” uses an HtmlTextWriter stored in the Response object.Response object is part of HttpContext.Writer sent into Render method.After pipeline complete, contents returned up the chain to aspnet_isapi.dll then http.sys.Results viewed on browser.

Extras

PostbacksASCX User ControlsMaster PagesASHX HandlersThemes & SkinsAJAXMVC

Process Summary

IIS

Worker Process

Pipeline (Modules)

Lifecycle (Handlers)

Render (Response)

What To Take Away From This

ASP.NET does much more than serve pagesDecoupled architecture allows flexible hostingPipeline and Page Life cycle – two different thingsExtensible architecture allows opportunities for interception and alterationModule and Handler do the workBe mindful of how much is happening behind the scenes

Resources

How ASP.NET Workshttp://www.west-wind.com/presentations/howaspnetworks/howaspnetworks.asp

ASP.NET Page Class Overviewhttp://msdn.microsoft.com/en-us/library/ms178138.aspx

IIS and the Process Modelhttp://dotnetslackers.com/articles/iis/ASPNETInternalsIISAndTheProcessModel.aspx

question & answer

www.microsoft.com/teched

International Content & Community

http://microsoft.com/technet

Resources for IT Professionals

http://microsoft.com/msdn

Resources for Developers

www.microsoft.com/learning

Microsoft Certification & Training Resources

Resources Tech·Ed Africa 2009 sessions will be made available for download the week after the event from: www.tech-ed.co.za

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