Basic understanding of ASP.NET HANDLERS and MODULES

1. ASP.NET
Handlers & Modules
Session Time: 30-45minutes
By: Sunil Pottumuttu

2. Agenda
• Introduction
• The Problem
• Extension Based Preprocessor
• Event Based Preprocessor
• Overall Picture
• Steps to Implement
• The Final Output

3. IIS & ASP.NET
Request Workflow
IIS
IIS
Application
*.asmx
aspnet_isapi.dll
HTTP Machine.config
Web.config
Request *.asp
asp.dll
HTTP
Process Request
Response

4. ASP.NET Configuration
• Machine.config defines default handlers or
handler factories to manage requests
• Web.config may alter Machine.config
settings at the application level

5. Machine.config Overrides Web.config
<httpHandlers>
<add verb="*" path="*.aspx" type="System.Web.UI.PageHandlerFactory"/>
<add verb="*" path="*.asmx"
type="System.Web.Services.Protocols.WebServiceHandlerFactory,
System.Web.Services, …/>
<add verb="*" path="*.soap"
type="System.Runtime.Remoting.Channels.Http.HttpRemotingHandlerFac
tory, System.Runtime.Remoting, …/>
<add verb="*" path="*.config" type="System.Web.HttpForbiddenHandler"/>
</httpHandlers>
<httpHandlers>
<add verb=“GET" path="*.xml"
type=“DotNetDashboard.Web.FileDownloadHandler, DotNetDashboard.Web,
Version=1.0.0.0, Culture=neutral, PublicKeyToken=xxx"/>
<add verb="*" path=“displayImage.aspx"
type=“DotNetDashboard.Web.ImageFormatter, DotNetDashboard.Web,
Version=1.0.0.0, Culture=neutral, PublicKeyToken=xxx” />
<add verb="*" path=“*.xls” type="System.Web.HttpForbiddenHandler"/>
</httpHandlers>

6. HttpHandler - The Extension
Based Preprocessor

7. HttpModule - Event Based
Preprocessor

8. Hook to the Events

9. Overall Picture

10. Some Handlers

11. IIS 7 – Handler Mappings & Demo

12. IIS 7 – Http Modules & Demo

13. Synchronous vs Asnchronous
• synchronous request, the ProcessRequest
method is executed, and any markup
produced is sent to the browser once the
entire request is processed
• BeginProcessRequest and the
EndProcessRequest

14. Virtual File Provider
• Global.asax provides hooks into the events of the ASP.NET pipeline
just like an httpModule
• Global.asax provides is the capability to add handlers to events not
available to modules, like Session_Start and Session_End.
• httpModules have over Global. asax is the ability to compile modules
into class libraries that can be used in multiple ASP.NET web sites

15. Modules vs Global.asax
• synchronous request, the ProcessRequest
method is executed, and any markup
produced is sent to the browser once the
entire request is processed
• BeginProcessRequest and the
EndProcessRequest

16. Imp Http Modules Events
• BeginRequest
• AuthenticateRequest
• AuthorizeRequest
• EndRequest
• Error

17. Demo Material