ASP.NET - Under the Covers

Harish RanganathanApplication Platform EvangelistMicrosoft India

AGENDA

• HTTP Runtime • HTTP Context

• IIS & ASP.NET Relation

• Global.asax

• HTTP Modules • Page Framework

• HTTP Handlers • Best Practices

HTTP Runtime• A low-level HTTP processing infrastructure

• Logical replacement for ISAPI filters/extensions

• Ability to add, replace, or remove core pieces of the product

• Benefits: Built-in thread pool, asynchronous support, access to ASP.NET intrinsic objects

HTTP Runtime

Http Runtimedemo

IIS-ASP.NET Relation

w3wp.exe (IIS 6.0)

http.sys (Kernel Mode)

IIS-ASP.NET Relation

Document types are mapped to ISAPI extensions in the IIS Manager

IIS – ASP.NET Relationdemo

HTTP Pipeline

HTTP Request IIS aspnet_isap

iHttpModule

s HttpHandler

HTTP Modules• Called before and after the handler

executes

• Ability to intercept, participate or modify each individual request into an application

Ex: Changing URL in request/response to hide server names behind firewall.

• The HTTP Application provides several events that modules can synchronize with

HTTP Modules• Global Application Events:

– Start – End

• Per request events (in order):

• Per request events (non-deterministic): – PreSendRequestHeaders– PreSendRequestContent– Error

– BeginRequest– AuthenticateRequest– AuthorizeRequest– ResolveRequestCache– AcquireRequestState

– PreRequestHandlerExecute – PostRequestHandlerExecute – ReleaseRequestState – UpdateRequestCache – EndRequest

HTTP Modules

Built-In HTTP Modules:

• Authentication Modules• Authorization Modules• OutputCache Module • SessionState Module• Configuring HTTP Modules

– Use httpModules section handler• View the Machine.Config

HTTP Handlers• Handlers:

– Are the endpoint in the request process– Only one handler is invoked per request

• Examples– ASP.NET Page Handler:

• Implements the ASP.NET Page Framework

• Processes all requests for .aspx pages– ASP.NET Service Handler:

• Implements Web Services• Processes all requests for .asmx pages

• Configuring HTTP Handlers

HTTP Handlers & Modulesdemo

HTTP Context• Encapsulates all information about an

individual HTTP request

• ASP.NET intrinsic objects are exposed as

properties of the HttpContext

• Modules and Handlers get a reference to an

HttpContext object representing the current

request

• Flows through the lifetime of a request

HTTP Context• ASP.NET supports all ASP classic members

Property Managed Class– Request HttpRequest– Response HttpResponse– Server HttpServerUtility– Session HttpSessionState– Application HttpApplicationState

• ASP.NET adds several new and useful members– Request.Files– Response.Cache– Error/User/Trace

Global.asax

• Extends on the familiar functionality of the

Global.asa

• Global.asax must be located in the root of a

Web application

• Enables easy handling of Application level

events without a custom HttpModule

Global.asaxUpdates:

• Are automatically detected

• Causes the Global.asax to be recompiled

• Restarts the HTTP Application

• ASP.NET completes all current requests

before shutting down old application

• Fires Application_End event

• Shuts down App Domain

HTTP Context & Global.asaxdemo

Page Framework

• Overview

• Page Object

• Page Lifecycle

• Page Events

• Control Tree

• Page Directives

Page Framework

Page Object:

• Inherits from Control, implements

IHttpHandler

• All .aspx pages inherit from Page

• Exposes the ASP.NET intrinsics

• Wires up events (Page_Load, Page_Init…)

Page Framework

Page Lifecycle:

Constructor PostBack Data Processing

ProcessRequest (hidden from user)

I nit

Render

PreRender

Dispose

PostBack Event Handling

Load

PostBack Change Notification

LoadViewState

SaveViewState

Page Frameworkdemo

Best Practices

• Return Multiple Resultsets

• Paged Data Access

• Connection Pooling

• ASP.NET Cache API

• Per Request caching

• Background Processing

Best Practices

• Page Output Caching and Proxy Servers

• Session State & Viewstate

• Debug vs. Release

• Exception Handling

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question & answer

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