ASP.NET Configuration

There are two files that you can use to control ASP.NET pages:

The Machine.config file influences all ASP.NET applications.
The Web.config file affects only the site that contains the Web.config file.

To make matters even muddier, you can place Web.config files in each folder or virtual directory of your site, and those settings will override settings in higher Web.config files.

Configuration File Elements

There are many elements that can be added to the System.Web section of your configuration files, as shown in Table 23-4.

Table 23-4: Configuration File System, Web Section Elements
Element	Description
`trace`	Controls page and application tracing
`globalizations`	Specifies character encodings to use with requests and responses
`httpRunTime`	Specifies the maximum time a page can execute, the maximum size of a request, and if fully qualified names should be used for client redirects
`compilation`	Specifies the default programming language for pages, whether a page is compiled in debug mode or release mode, and the assemblies available to the application
`pages`	Specifies configuration information for a page
`customErrors`	Determines how errors are displayed
`authentication`	Specifies authentication settings
`identity`	Configures user account settings for impersonation
`authorization`	Determines the users and roles that can access pages
`machineKey`	Used to share encryption key information across a Web farm
`trust`	Sets security policy settings
`securityPolicy`	Contains a list of security policies
`sessionState`	Sets session state information such as in-process, out-of-process, or cookieless
`httpHandlers`	Associates a particular HTTP handler with a specific page path and request verb
`httpModules`	Lists the modules involved in page requests
`processModel`	Contains process-wide settings that control the `aspnet` _ `wp` processes
`webControls`	Sets the location of client-side scripts used with Web controls `clientTarget`	Lists values that are used by the `ClientTarget` property
`browserCaps`	Lists information about the capabilities of individual browser types
`webServices`	Configures settings for Web Services

The Web.config file provides for a Location property, which lets you set specific pages or specific paths.

<configuration>
              <location path="MyVirtualDirectory">
                        <system.web>
                        </system.web>
              </location>
              <location path="MyPage.aspx" allowOverrides="false">
                        <system.web>
                        </system.web>
              </location>
</configuration>

Configuration Attributes

You can set various attributes for the configuration file elements. Tables 23-5 through 23-8 show the attributes for the node, httpRuntime, processModel, and trace elements.

Table 23-5: Authentication Attributes for the Node Element
Value	Description
`Windows`	Uses credentials provided by IIS. The `authorization` element can be used to control access further.
`Forms`	Provides for custom authorization.
`Passport`	Allows for the use of passport authentication.
`None`	Disables authentication at the ASP.NET level.

Table 23-6: httpRuntime Attributes
Attributes	Description
`appRequestQueueLimit`	Specifies the limit for request queuing. Once this limit is reached, the server returns 503 errors. The default value is 100.
`executionTimeout`	Sets the amount of time that a request can execute before timing out. The default is 90 seconds.
`MaxRequestLength`	Sets the maximum file size that can be uploaded. The default value is 4KB. This is primarily used to prevent denial-of-service attacks.
`MinFreeLocalRequestFreeThreads`	Sets the minimum number of threads reserved for local requests. The default is 4.
`minFreeThreads`	Sets the minimum number of threads reserved for requests that require additional threads. The default is 8.
`useFullyQualifiedRedirectUrl`	Determines if URLs sent to the client are fully qualified or relative.

Table 23-7: processModel Attributes
Attribute	Description
`Enable`	Determines if process model settings are used.
`Timeout`	Sets the lifespan of the process. The default level is infinite.
`idleTimeout`	Sets the lifespan of an `aspnet_wp` process when idle. The default is infinite.
`shutdownTimeout`	Sets the amount of time the process can be shut down gracefully. The default is 5 seconds.
`requestLimit`	Sets the number of requests that can be processed by ASP.NET before it is shut down. The default is infinite.
`requestQueueLimit`	Sets the number of requests that can be queued before the process is shut down. The default is 50000.
`memoryLimit`	Sets the amount of memory that can be used by the `aspnet_wp` process before it will be recycled. The default is 60 percent.
`cpuMask`	Used in a Web garden where `aspnet_wp` affinity is set on processors.
`webGarden`	Enables Web gardening.
`Username`	Sets the username that an `aspnet_wp` process runs under.
`comAuthenticationLevel`	Sets the DCOM authentication level.
`comImpersonationLevel`	Sets the DCOM impersonation level.
`responseRestartDeadlockInterval`	Sets the amount of time that will be allowed between process restarts due to deadlocking. The default is 9 minutes.
`responseDeadlockInterval`	Sets the amount of time allowed without a response when requests are queued. The default is 3 minutes.
`maxWorkerThreads`	Sets the maximum limit of worker threads per CPU in the thread pool.
`maxIoThreads`	Set the maximum limit on the number of IO threads per processor.

Table 23-8: Trace Attributes
Attribute	Description
`Enabled`	Enables tracing. The default is false.
`localOnly`	Determines if tracing can be viewed remotely. The default is true.
`pageOutput`	Sets whether trace output is rendered at the bottom of the page or available via trace.axd. The default is false.
`requestLimit`	Sets the number of traces that can be stored in the trace buffer and be viewed by trace.axd. The default is 10.
`traceMode`	Sets the sort order of trace items. The default is `SortByTime`.

AppSettings Configurations

You can add your own custom settings by using the appSettings elements. To do this, configure your Web.config file as follows:

<configuration>
              <appSettings>
                        <add key="MyName" value="Greg MacBeth" />
              </appSettings>
</configuration>

You can read these settings with the following code:

string Name = ConfigurationSettings.AppSettings("MyName");

Important HTTP Classes

There are two important HTTP classes. One handles responses, and the other handles requests.

HttpRequest allows the gathering of data from the Web client. For example, you can get the authentication method, hostname, and address.
HttpResponse exposes data that will be sent to the client browser.