Logo
programming4us
programming4us
programming4us
programming4us
Home
programming4us
XP
programming4us
Windows Vista
programming4us
Windows 7
programming4us
Windows Azure
programming4us
Windows Server
programming4us
Windows Phone
 
Windows XP

Microsoft ASP.NET 4 : HTTP Handlers - The Built-in Handlers

7/8/2011 6:09:18 PM
One of the best examples of custom handling is the Trace handler built into ASP.NET. You turn tracing on in the web.config file by inserting the trace element, <trace enabled=true />. This instructs the ASP.NET runtime to store summaries of the requests going through the site so that they can be viewed for diagnostic purposes.

ASP.NET caches the tracing output in memory. To view the trace results, you surf to the virtual directory managing the site and ask for a specific resource: Trace.axd. Take a look at this Example and you'll see the first entry among all the standard HTTP handlers is for a resource named Trace.axd. The tracing functionality behind ASP.NET falls outside of normal UI processing, so it makes sense that tracing is handled by a custom handler.

When you surf to the Trace.axd resource, the handler renders HTML that looks like the output shown in Figure 1. The processing for this handler is very specific—the handler's job is to render the results of the last few requests.

Figure 1. The output of the Trace.axd handler.


As shown in Figure 2, clicking the View Details link resubmits the request with a parameter id=3 in the query string. This causes the handler to render the details of the third request.

Figure 2. The output of the Trace.axd handler focused on a specific request summary.


Figure 3 shows the Microsoft Internet Information Services (IIS) file mapping for files with the .axd extension. Although you won't really see this aspect until deployment time, it's interesting to observe because it shows how ASP.NET is very versatile in the kinds of requests it can handle. IIS handles Trace.axd requests the same way as any other ASP.NET request. That means IIS will pass requests for resources with an extension of .axd on to ASP.NET. Once inside the ASP.NET pipeline, the web.config file tells ASP.NET to handle the request with the Trace handler.

Figure 3. IIS has a handler mapping for Trace.axd.


If you look through the default web.config file a bit more, you'll see some other critical ASP.NET handlers. As you might expect, source code is banned explicitly from normal clients by default. Notice that files such as *.cs, *.config, and *.vb are handled by the Forbidden handler. If you try to look at source code in a Web browser, ASP.NET returns the page shown in Figure 4 by default.

Figure 4. What happens when you try to view forbidden content.


Remember that ASP.NET's configuration is very malleable and that you can choose to let clients see your source code by one of two means. You can remove the source code extension to ASP.NET mappings in IIS. Alternatively, you can write your own source code viewer handlers and declare them in your application's web.config file.

These handlers plug into the pipeline by implementing IHttpHandler. The next section describes this key interface.
Other -----------------
- Microsoft ASP.NET 4 : ASP.NET Request Handlers
- Microsoft ASP.NET 4 : HttpModules (part 2) - Seeing Active Modules & Storing State in Modules
- Microsoft ASP.NET 4 : HttpModules (part 1) - Existing Modules & Implementing a Module
- Microsoft ASP.NET 4 : The HttpApplication Class and HTTP Modules - Overriding HttpApplication
- Microsoft ASP.NET 4 : Diagnostics and Debugging - Error Pages
- Microsoft ASP.NET 4 : Diagnostics and Debugging - Debugging with Visual Studio
- Microsoft ASP.NET 4 : Diagnostics and Debugging - Application Tracing
- Microsoft ASP.NET 4 : Diagnostics and Debugging - Page Tracing
- Microsoft ASP.NET 4 : Caching and State Management - The Wizard Control: An Alternative to Session State
- Microsoft ASP.NET 4 : Caching and State Management - Tracking Session State
 
 
Top 10
- Sharepoint 2013 : New Installation and Configuration - Configuring Your SharePoint Farm
- Microsoft Dynamics CRM 4.0 : SharePoint Integration - Store Attachments in SharePoint Using a Custom Solution
- Migrating to Exchange Server 2007 : Migrating from Exchange 2000 Server or Exchange Server 2003 to Exchange Server 2007 (part 2)
- Maintaining Windows 7 : Check Your Hard Drive for Errors
- Personalizing and Configuring Windows 7 : The Windows 7 User Interface (part 3) - Branding Windows 7 like a PC Maker
- Duplicating and Copying DVDs (part 2) - Ripping DVDs to the PC
- Windows Phone 8 : Configuring Basic Device Settings - Wi-Fi Networking (part 2) - Removing Known Networks
- Client Access to Exchange Server 2007 : Using Outlook 2007 Collaboratively (part 1)
- Windows Phone 7 : AlienShooter Enhancements (part 2) - Tombstone Support, Particle System
- Microsoft Exchange Server 2007 : Single Copy Clusters (part 2) - Installing Exchange Server 2007 on the Active Node
Popular tags
Microsoft Access Microsoft Excel Microsoft OneNote Microsoft PowerPoint Microsoft Project Microsoft Visio Microsoft Word Active Directory Biztalk Exchange Server Microsoft LynC Server Microsoft Dynamic Sharepoint Sql Server Windows Server 2008 Windows Server 2012 Windows 7 Windows 8 windows Phone 7 windows Phone 8
programming4us programming4us
 
Popular keywords
HOW TO Swimlane in Visio Visio sort key Pen and Touch Creating groups in Windows Server Raid in Windows Server Exchange 2010 maintenance Exchange server mail enabled groups Debugging Tools Collaborating
programming4us programming4us
PS4 game trailer XBox One game trailer
WiiU game trailer 3ds game trailer
 
programming4us
Natural Miscarriage
programming4us
Windows Vista
programming4us
Windows 7
programming4us
Windows Azure
programming4us
Windows Server
programming4us
Game Trailer