section Element for configSections (General Settings Schema)

  • Article

Defines an association between a configuration section handler and a configuration element.

<section 
   name="section name"
   type="configuration section handler class, assembly file name, version, culture, public key token"
   allowDefinition= "Everywhere|MachineOnly|MachineToApplication|MachineToWebRoot" 
   allowLocation="True|False" 
   restartOnExternalChanges="True|False" 
/>

Attributes and Elements

The following sections describe attributes, child elements, and parent elements.

Attributes

Attribute Description

allowDefinition

Optional Boolean attribute.

Applies to ASP.NET applications only.

Specifies which configuration file the section can be used in.

This attribute can be one of the following values (defined in the ConfigurationAllowDefinition enumeration) in order of decreasing scope.

Value Description

Everywhere

Allows the section to be configured in any configuration file or directory, as follows:

  • Machine.config.

  • Root Web.config.

  • Web.config for an application.

  • Virtual directory.

  • Physical sub-directory in the application.

If no allowDefinition attribute is used, Everywhere is assumed. This is the default.

MachineToApplication

Allows the section to be configured in one of the following files:

  • Machine.config.

  • Root Web.config.

  • Web.config for an application.

This excludes Web.config files in virtual directories or a physical subdirectory in the application.

MachineToWebRoot

Allows the section to be configured in one of the following files:

  • Machine.config.

  • Root Web.config.

Both the Machine.config and root Web.config files are located in %SystemRoot%\Microsoft.NET\Framework\versionNumber\CONFIG.

MachineOnly

Allows the section to be configured only in the Machine.config file, which is located in %SystemRoot%\Microsoft.NET\Framework\versionNumber\CONFIG.

allowExeDefinition

Optional Boolean attribute.

Applies to .NET Framework client applications only.

Specifies which configuration file the section can be used in.

This attribute can be one of the following values (defined in the ConfigurationAllowExeDefinition enumeration) in order of decreasing scope.

Value Description

MachineToApplication

Allows the section to be configured in one of the following files:

  • Machine.config.

  • Application configuration.

MachineToRoamingUser

MachineToLocalUser

MachineOnly

Allows the section to be configured only in the Machine.config file, which is located in %SystemRoot%\Microsoft.NET\Framework\versionNumber\CONFIG.

allowLocation

Optional Boolean attribute.

Applies to ASP.NET applications only.

Specifies whether the section can be used within the location element.

The default is True.

name

Required String attribute.

Specifies the name of the configuration section or element that is associated with the configuration section handler that is specified in the type attribute. This is the name of the element as it appears in the section settings area of the configuration file.

restartOnExternalChanges

Optional Boolean attribute.

Does not apply to ASP.NET applications.

Specifies whether the application should restart, if the configuration data for the section changes.

type

Required String attribute.

Specifies the name of the configuration section handler class that handles the processing of the configuration settings in the section or element that is specified in the name attribute. Use the following format:

type="Fully qualified class name, assembly file name, version, culture, public key token"

The definition must match the assembly reference. For example, if the version number in the following example syntax does not match the assembly, an error occurs.

type="MyConfigSectionHandler.MyHandler,MyCustomConfigurationHandler,Version=1.0.0.0,Culture=neutral,PublicKeyToken=null"

The assembly file must be located in the same application directory as the Web.config file that defines the assembly file. In the case of the root Web.config file or the Machine.config file, the assembly file must be in %SystemRoot%\Microsoft.NET\Framework\version.

Child Elements

None.

Parent Elements

Element Description

configuration

Specifies the required root element in every configuration file that is used by the common language runtime and the .NET Framework applications.

configSections

Specifies configuration section and namespace declarations.

sectionGroup

Defines an association between a configuration section handler and a configuration section.

Remarks

A section element associates a configuration section handler with a configuration element or section. This is required because ASP.NET makes no presumptions about how to handle settings within a configuration file. Instead, ASP.NET delegates the processing of configuration data to configuration section handlers. Each section element identifies a configuration section or element and the associated class that is derived from ConfigurationSection that handles the configuration section or element. The section elements can be logically grouped in sectionGroup elements for organization and to help avoid naming conflicts. The section and sectionGroup elements are contained in the configSections element.

Default Configuration

Configuration sections for the .NET Framework configuration elements are defined in the Machine.config file and are too numerous to list here. The following excerpt from the Machine.config file defines the configuration section handler for the authentication element of the system.web section. Then, configuration settings are defined for the authentication element.

If a configuration section handler is not associated with a configuration element, ASP.NET issues the server error, "Unrecognized configuration section element_name."

<configuration>
    <configSections>
        <sectionGroup name="system.web" type="System.Web.Configuration.SystemWebSectionGroup, System.Web, Version=%ASSEMBLY_VERSION%, Culture=neutral, PublicKeyToken=%MICROSOFT_PUBLICKEY%">
            <section name="authentication" type="System.Web.Configuration.AuthenticationSection, System.Web, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" allowDefinition="MachineToApplication" />
            <!-- Other system.web sections -->
        </sectionGroup>
        <!-- Other configuration sections -->
    </configSections>

    <system.web>
        <authentication mode="Windows">
            <forms name=".ASPXAUTH" 
                   loginUrl="login.aspx" defaultUrl="default.aspx" 
                   protection="All" 
                   timeout="30" 
                   path="/" 
                   requireSSL="False" 
                   slidingExpiration="True" 
                   cookieless="UseCookies" 
                   domain="" 
                   enableCrossAppRedirects="False">
                <credentials passwordFormat="SHA1" />
            </forms>
            <passport redirectUrl="internal" />
        </authentication>
        <!-- Other system.web elements -->
    </system.web>
    <!-- Other configuration settings -->
</configuration>

Example

The following code example shows how to define a custom configuration section and define settings for that section.

<configuration>

   <configSections>
      <section name="sampleSection"
               type="System.Configuration.SingleTagSectionHandler" />
   </configSections>

   <sampleSection setting1="Value1" 
                  setting2="value two" 
                  setting3="third value" />

</configuration>

Element Information

Configuration section handler

Does not apply.

Configuration member

ConfigurationSection

Configurable locations

Machine.config

Root-level Web.config

Application-level Web.config

Virtual or physical directory–level Web.config

Requirements

Microsoft Internet Information Services (IIS) 5.0, 5.1, or 6.0

The .NET Framework version 1.0, 1.1, or 2.0

Microsoft Visual Studio 2003 or Visual Studio 2005

See Also

Reference

configSections Element (General Settings Schema)
sectionGroup Element for configSections (General Settings Schema)
clear Element for configSections (General Settings Schema)
remove Element for configSections (General Settings Schema)
configuration Element (General Settings Schema)

Concepts

ASP.NET Configuration File Hierarchy and Inheritance
Format of ASP.NET Configuration Files
ASP.NET Configuration Scenarios

Other Resources

General Configuration Settings (ASP.NET)
ASP.NET Configuration Settings
ASP.NET Configuration Files
Configuring ASP.NET Applications
ASP.NET Configuration API