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.NET Framework Class Library

HttpWebRequest Class

Provides an HTTP-specific implementation of the WebRequest class.

Namespace:  System.Net
Assembly:  System (in System.dll)
<SerializableAttribute> _
Public Class HttpWebRequest _
	Inherits WebRequest _
	Implements ISerializable

The HttpWebRequest type exposes the following members.

  Name Description
Public method HttpWebRequest() Obsolete. Initializes a new instance of the HttpWebRequest class.
Protected method HttpWebRequest(SerializationInfo, StreamingContext) Obsolete. Initializes a new instance of the HttpWebRequest class from the specified instances of the SerializationInfo and StreamingContext classes.
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  Name Description
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps Accept Gets or sets the value of the Accept HTTP header.
Public property Address Gets the Uniform Resource Identifier (URI) of the Internet resource that actually responds to the request.
Public property AllowAutoRedirect Gets or sets a value that indicates whether the request should follow redirection responses.
Public property Supported in .NET for Windows Store apps AllowReadStreamBuffering Gets or sets a value that indicates whether to buffer the received from the Internet resource.
Public property AllowWriteStreamBuffering Gets or sets a value that indicates whether to buffer the data sent to the Internet resource.
Public property AuthenticationLevel Gets or sets values indicating the level of authentication and impersonation used for this request. (Inherited from WebRequest.)
Public property AutomaticDecompression Gets or sets the type of decompression that is used.
Public property CachePolicy Gets or sets the cache policy for this request. (Inherited from WebRequest.)
Public property ClientCertificates Gets or sets the collection of security certificates that are associated with this request.
Public property Connection Gets or sets the value of the Connection HTTP header.
Public property ConnectionGroupName Gets or sets the name of the connection group for the request. (Overrides WebRequest.ConnectionGroupName.)
Public property ContentLength Gets or sets the Content-length HTTP header. (Overrides WebRequest.ContentLength.)
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps ContentType Gets or sets the value of the Content-type HTTP header. (Overrides WebRequest.ContentType.)
Public property ContinueDelegate Gets or sets the delegate method called when an HTTP 100-continue response is received from the Internet resource.
Public property Supported in .NET for Windows Store apps ContinueTimeout Gets or sets a timeout, in milliseconds, to wait until the 100-Continue is received from the server.
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps CookieContainer Gets or sets the cookies associated with the request.
Public property CreatorInstance Obsolete. When overridden in a descendant class, gets the factory object derived from the IWebRequestCreate class used to create the WebRequest instantiated for making the request to the specified URI. (Inherited from WebRequest.)
Public property Supported in .NET for Windows Store apps Credentials Gets or sets authentication information for the request. (Overrides WebRequest.Credentials.)
Public property Date Get or set the Date HTTP header value to use in an HTTP request.
Public property Static member DefaultCachePolicy Gets or sets the default cache policy for this request.
Public property Static member DefaultMaximumErrorResponseLength Gets or sets the default maximum length of an HTTP error response.
Public property Static member DefaultMaximumResponseHeadersLength Gets or sets the default for the MaximumResponseHeadersLength property.
Public property Expect Gets or sets the value of the Expect HTTP header.
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps HaveResponse Gets a value that indicates whether a response has been received from an Internet resource.
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps Headers Specifies a collection of the name/value pairs that make up the HTTP headers. (Overrides WebRequest.Headers.)
Public property Host Get or set the Host header value to use in an HTTP request independent from the request URI.
Public property IfModifiedSince Gets or sets the value of the If-Modified-Since HTTP header.
Public property ImpersonationLevel Gets or sets the impersonation level for the current request. (Inherited from WebRequest.)
Public property KeepAlive Gets or sets a value that indicates whether to make a persistent connection to the Internet resource.
Public property MaximumAutomaticRedirections Gets or sets the maximum number of redirects that the request follows.
Public property MaximumResponseHeadersLength Gets or sets the maximum allowed length of the response headers.
Public property MediaType Gets or sets the media type of the request.
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps Method Gets or sets the method for the request. (Overrides WebRequest.Method.)
Public property Pipelined Gets or sets a value that indicates whether to pipeline the request to the Internet resource.
Public property PreAuthenticate Gets or sets a value that indicates whether to send an Authorization header with the request. (Overrides WebRequest.PreAuthenticate.)
Public property ProtocolVersion Gets or sets the version of HTTP to use for the request.
Public property Proxy Gets or sets proxy information for the request. (Overrides WebRequest.Proxy.)
Public property ReadWriteTimeout Gets or sets a time-out in milliseconds when writing to or reading from a stream.
Public property Referer Gets or sets the value of the Referer HTTP header.
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps RequestUri Gets the original Uniform Resource Identifier (URI) of the request. (Overrides WebRequest.RequestUri.)
Public property SendChunked Gets or sets a value that indicates whether to send data in segments to the Internet resource.
Public property ServerCertificateValidationCallback Gets or sets a callback function to validate the server certificate.
Public property ServicePoint Gets the service point to use for the request.
Public property Supported by Portable Class Library Supported in .NET for Windows Store apps SupportsCookieContainer Gets a value that indicates whether the request provides support for a CookieContainer.
Public property Timeout Gets or sets the time-out value in milliseconds for the GetResponse and GetRequestStream methods. (Overrides WebRequest.Timeout.)
Public property TransferEncoding Gets or sets the value of the Transfer-encoding HTTP header.
Public property UnsafeAuthenticatedConnectionSharing Gets or sets a value that indicates whether to allow high-speed NTLM-authenticated connection sharing.
Public property Supported in .NET for Windows Store apps UseDefaultCredentials Gets or sets a Boolean value that controls whether default credentials are sent with requests. (Overrides WebRequest.UseDefaultCredentials.)
Public property UserAgent Gets or sets the value of the User-agent HTTP header.
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  Name Description
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps Abort Cancels a request to an Internet resource. (Overrides WebRequest.Abort().)
Public method AddRange(Int32) Adds a byte range header to a request for a specific range from the beginning or end of the requested data.
Public method AddRange(Int64) Adds a byte range header to a request for a specific range from the beginning or end of the requested data.
Public method AddRange(Int32, Int32) Adds a byte range header to the request for a specified range.
Public method AddRange(Int64, Int64) Adds a byte range header to the request for a specified range.
Public method AddRange(String, Int32) Adds a Range header to a request for a specific range from the beginning or end of the requested data.
Public method AddRange(String, Int64) Adds a Range header to a request for a specific range from the beginning or end of the requested data.
Public method AddRange(String, Int32, Int32) Adds a range header to a request for a specified range.
Public method AddRange(String, Int64, Int64) Adds a range header to a request for a specified range.
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps BeginGetRequestStream Begins an asynchronous request for a Stream object to use to write data. (Overrides WebRequest.BeginGetRequestStream(AsyncCallback, Object).)
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps BeginGetResponse Begins an asynchronous request to an Internet resource. (Overrides WebRequest.BeginGetResponse(AsyncCallback, Object).)
Public method CreateObjRef Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps EndGetRequestStream(IAsyncResult) Ends an asynchronous request for a Stream object to use to write data. (Overrides WebRequest.EndGetRequestStream(IAsyncResult).)
Public method EndGetRequestStream(IAsyncResult, TransportContext) Ends an asynchronous request for a Stream object to use to write data and outputs the TransportContext associated with the stream.
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps EndGetResponse Ends an asynchronous request to an Internet resource. (Overrides WebRequest.EndGetResponse(IAsyncResult).)
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps Equals(Object) Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected method Supported by Portable Class Library Supported in .NET for Windows Store apps Finalize Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps GetHashCode Serves as the default hash function. (Inherited from Object.)
Public method GetLifetimeService Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected method GetObjectData Infrastructure. Populates a SerializationInfo with the data required to serialize the target object. (Overrides WebRequest.GetObjectData(SerializationInfo, StreamingContext).)
Public method GetRequestStream() Gets a Stream object to use to write request data. (Overrides WebRequest.GetRequestStream().)
Public method GetRequestStream(TransportContext) Gets a Stream object to use to write request data and outputs the TransportContext associated with the stream.
Public method Supported in .NET for Windows Store apps GetRequestStreamAsync When overridden in a descendant class, returns a Stream for writing data to the Internet resource as an asynchronous operation. (Inherited from WebRequest.)
Public method GetResponse Returns a response from an Internet resource. (Overrides WebRequest.GetResponse().)
Public method Supported in .NET for Windows Store apps GetResponseAsync When overridden in a descendant class, returns a response to an Internet request as an asynchronous operation. (Inherited from WebRequest.)
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps GetType Gets the Type of the current instance. (Inherited from Object.)
Public method InitializeLifetimeService Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected method Supported by Portable Class Library Supported in .NET for Windows Store apps MemberwiseClone() Creates a shallow copy of the current Object. (Inherited from Object.)
Protected method MemberwiseClone(Boolean) Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Public method Supported by Portable Class Library Supported in .NET for Windows Store apps ToString Returns a string that represents the current object. (Inherited from Object.)
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  Name Description
Explicit interface implemetation Private method ISerializable.GetObjectData Infrastructure. Populates a SerializationInfo with the data needed to serialize the target object.
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The HttpWebRequest class provides support for the properties and methods defined in WebRequest and for additional properties and methods that enable the user to interact directly with servers using HTTP.

Do not use the HttpWebRequest constructor. Use the WebRequest.Create method to initialize new HttpWebRequest objects. If the scheme for the Uniform Resource Identifier (URI) is http:// or https://, Create returns an HttpWebRequest object.

The GetResponse method makes a synchronous request to the resource specified in the RequestUri property and returns an HttpWebResponse that contains the response. You can make an asynchronous request to the resource using the BeginGetResponse and EndGetResponse methods.

When you want to send data to the resource, the GetRequestStream method returns a Stream object to use to send data. The BeginGetRequestStream and EndGetRequestStream methods provide asynchronous access to the send data stream.

For client authentication with HttpWebRequest, the client certificate must be installed in the My certificate store of the current user.

The HttpWebRequest class throws a WebException when errors occur while accessing a resource. The WebException.Status property contains a WebExceptionStatus value that indicates the source of the error. When WebException.Status is WebExceptionStatus.ProtocolError, the Response property contains the HttpWebResponse received from the resource.

HttpWebRequest exposes common HTTP header values sent to the Internet resource as properties, set by methods, or set by the system; the following table contains a complete list. You can set other headers in the Headers property as name/value pairs. Note that servers and caches may change or add headers during the request.

The following table lists the HTTP headers that are set either by properties or methods or the system.

Header

Set by

Accept

Set by the Accept property.

Connection

Set by the Connection property, KeepAlive property.

Content-Length

Set by the ContentLength property.

Content-Type

Set by the ContentType property.

Expect

Set by the Expect property.

Date

Set by the system to current date.

Host

Set by the system to current host information.

If-Modified-Since

Set by the IfModifiedSince property.

Range

Set by the AddRange method.

Referer

Set by the Referer property.

Transfer-Encoding

Set by the TransferEncoding property (the SendChunked property must be true).

User-Agent

Set by the UserAgent property.

Note Note

HttpWebRequest is registered automatically. You do not need to call the RegisterPrefix method to register System.Net.HttpWebRequest before using URIs beginning with http:// or https://.

The local computer or application config file may specify that a default proxy be used. If the Proxy property is specified, then the proxy settings from the Proxy property override the local computer or application config file and the HttpWebRequest instance will use the proxy settings specified. If no proxy is specified in a config file and the Proxy property is unspecified, the HttpWebRequest class uses the proxy settings inherited from Internet Explorer on the local computer. If there are no proxy settings in Internet Explorer, the request is sent directly to the server.

The HttpWebRequest class parses a proxy bypass list with wildcard characters inherited from Internet Explorer differently than the bypass list is parsed directly by Internet Explorer. For example, the HttpWebRequest class will parse a bypass list of "nt*" from Internet Explorer as a regular expression of "nt.$". This differs from the native behavior of Internet Explorer. So a URL of "http://intxxxxx" would bypass the proxy using the HttpWebRequest class, but would not bypass the proxy using Internet Explorer.

Note Note

The Framework caches SSL sessions as they are created and attempts to reuse a cached session for a new request, if possible. When attempting to reuse an SSL session, the Framework uses the first element of ClientCertificates (if there is one), or tries to reuse an anonymous sessions if ClientCertificates is empty.

Note Note

For security reasons, cookies are disabled by default. If you want to use cookies, use the CookieContainer property to enable cookies.

The following code example creates an HttpWebRequest for the URI http://www.contoso.com/.


        Dim myReq As HttpWebRequest = _
            WebRequest.Create("http://www.contoso.com/")

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1
  • WebPermission  

    to access the requested URI or any URI that the request is redirected to. Associated enumeration: Connect

Windows Phone 8.1, Windows Phone 8, 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.