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HttpListenerElement Class

Represents the HttpListener element in the configuration file. This class cannot be inherited.

System.Object
  System.Configuration.ConfigurationElement
    System.Net.Configuration.HttpListenerElement

Namespace:  System.Net.Configuration
Assembly:  System (in System.dll)

public sealed class HttpListenerElement : ConfigurationElement

The HttpListenerElement type exposes the following members.

  NameDescription
Public methodHttpListenerElementInitializes a new instance of the HttpListenerElement class.
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  NameDescription
Public propertyCurrentConfigurationGets a reference to the top-level Configuration instance that represents the configuration hierarchy that the current ConfigurationElement instance belongs to. (Inherited from ConfigurationElement.)
Public propertyElementInformationGets an ElementInformation object that contains the non-customizable information and functionality of the ConfigurationElement object. (Inherited from ConfigurationElement.)
Protected propertyElementPropertyGets the ConfigurationElementProperty object that represents the ConfigurationElement object itself. (Inherited from ConfigurationElement.)
Protected propertyItem[ConfigurationProperty]Gets or sets a property or attribute of this configuration element. (Inherited from ConfigurationElement.)
Protected propertyItem[String]Gets or sets a property, attribute, or child element of this configuration element. (Inherited from ConfigurationElement.)
Public propertyLockAllAttributesExceptGets the collection of locked attributes. (Inherited from ConfigurationElement.)
Public propertyLockAllElementsExceptGets the collection of locked elements. (Inherited from ConfigurationElement.)
Public propertyLockAttributesGets the collection of locked attributes (Inherited from ConfigurationElement.)
Public propertyLockElementsGets the collection of locked elements. (Inherited from ConfigurationElement.)
Public propertyLockItemGets or sets a value indicating whether the element is locked. (Inherited from ConfigurationElement.)
Protected propertyPropertiesGets the collection of properties. (Inherited from ConfigurationElement.)
Public propertyTimeoutsGets the default timeout elements used for an HttpListener object.
Public propertyUnescapeRequestUrlGets a value that indicates if HttpListener uses the raw unescaped URI instead of the converted URI.
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  NameDescription
Protected methodDeserializeElementReads XML from the configuration file. (Inherited from ConfigurationElement.)
Public methodEqualsCompares the current ConfigurationElement instance to the specified object. (Inherited from ConfigurationElement.)
Public methodGetHashCodeGets a unique value representing the current ConfigurationElement instance. (Inherited from ConfigurationElement.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodInitSets the ConfigurationElement object to its initial state. (Inherited from ConfigurationElement.)
Protected methodInitializeDefaultUsed to initialize a default set of values for the ConfigurationElement object. (Inherited from ConfigurationElement.)
Protected methodIsModifiedIndicates whether this configuration element has been modified since it was last saved or loaded, when implemented in a derived class. (Inherited from ConfigurationElement.)
Public methodIsReadOnlyGets a value indicating whether the ConfigurationElement object is read-only. (Inherited from ConfigurationElement.)
Protected methodResetResets the internal state of the ConfigurationElement object, including the locks and the properties collections. (Inherited from ConfigurationElement.)
Protected methodResetModifiedResets the value of the IsModified method to false when implemented in a derived class. (Inherited from ConfigurationElement.)
Protected methodSerializeElementWrites the contents of this configuration element to the configuration file when implemented in a derived class. (Inherited from ConfigurationElement.)
Protected methodSerializeToXmlElementWrites the outer tags of this configuration element to the configuration file when implemented in a derived class. (Inherited from ConfigurationElement.)
Protected methodSetReadOnlySets the IsReadOnly property for the ConfigurationElement object and all subelements. (Inherited from ConfigurationElement.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodUnmergeModifies the ConfigurationElement object to remove all values that should not be saved. (Inherited from ConfigurationElement.)
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This class corresponds to the <httpListener> Element (Network Settings) configuration element. This class provides programmatic access to information that can be stored in configuration files.

The UnescapeRequestUrl property indicates if HttpListener uses the raw unescaped URI instead of the converted URI where any percent-encoded values are converted and other normalization steps are taken.

When a HttpListener instance receives a request through the http.sys service, it creates an instance of the URI string provided by http.sys, and exposes it as the HttpListenerRequest.Url property.

The http.sys service exposes two request URI strings:

  • Raw URI

  • Converted URI

The raw URI is the System.Uri provided in the request line of a HTTP request:

GET /path/

Host: www.contoso.com

The raw URI provided by http.sys for the request mentioned above, is "/path/". This represents the string following the HTTP verb as it was sent over the network.

The http.sys service creates a converted URI from the information provided in the request by using the URI provided in the HTTP request line and the Host header to determine the origin server the request should be forwarded to. This is done by comparing the information from the request with a set of registered URI prefixes. The HTTP Server SDK documentation refers to this converted URI as the HTTP_COOKED_URL structure.

In order to be able to compare the request with registered URI prefixes, some normalization to the request needs to be done. For the sample above the converted URI would be as follows:

http://www.contoso.com/path/

The http.sys service combines the Uri.Host property value and the string in the request line to create a converted URI. In addition, http.sys and the System.Uri class also do the following:

  • Un-escapes all percent encoded values.

  • Converts percent-encoded non-ASCII characters into a UTF-16 character representation. Note that UTF-8 and ANSI/DBCS characters are supported as well as Unicode characters (Unicode encoding using the %uXXXX format).

  • Executes other normalization steps, like path compression.

Since the request doesn't contain any information about the encoding used for percent-encoded values, it may not be possible to determine the correct encoding just by parsing the percent-encoded values.

Therefore http.sys provides two registry keys for modifying the process:

Registry Key

Default Value

Description

EnableNonUTF8

1

If zero, http.sys accepts only UTF-8-encoded URLs.

If non-zero, http.sys also accepts ANSI-encoded or DBCS-encoded URLs in requests.

FavorUTF8

1

If non-zero, http.sys always tries to decode a URL as UTF-8 first; if that conversion fails and EnableNonUTF8 is non-zero, Http.sys then tries to decode it as ANSI or DBCS.

If zero (and EnableNonUTF8 is non-zero), http.sys tries to decode it as ANSI or DBCS; if that is not successful, it tries a UTF-8 conversion.

When HttpListener receives a request, it uses the converted URI from http.sys as input to the Url property.

There is a need for supporting characters besides characters and numbers in URIs. An example is the following URI, which is used to retrieve customer information for customer number "1/3812":

http://www.contoso.com/Customer('1%2F3812')/

Note the percent-encoded slash in the Uri (%2F). This is necessary, since in this case the slash character represents data and not a path delimiter.

Passing the string to Uri constructor will lead to the following URI:

http://www.contoso.com/Customer('1/3812')/

Splitting the path into its segments would result in the following elements:

Customer('1

3812')

This is not the intent of the sender of the request.

If the UnescapeRequestUrl property is set to false, then when the HttpListener receives a request, it uses the raw URI instead of the converted URI from http.sys as input to the Url property.

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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