HttpWebRequest Class

Article
01/16/2013

[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]

Provides an HTTP-specific implementation of the WebRequest class.

Inheritance Hierarchy

System. . :: . .Object
  System. . :: . .MarshalByRefObject
    System.Net. . :: . .WebRequest
      System.Net..::..HttpWebRequest

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

Syntax

'Declaration
Public Class HttpWebRequest _
    Inherits WebRequest

public class HttpWebRequest : WebRequest

public ref class HttpWebRequest : public WebRequest

type HttpWebRequest =  
    class
        inherit WebRequest
    end

public class HttpWebRequest extends WebRequest

The HttpWebRequest type exposes the following members.

Properties

	Name	Description
	Accept	Gets or sets the value of the Accept HTTP header.
	Address	Gets the Uniform Resource Identifier (URI) of the Internet resource that actually responds to the request.
	AllowAutoRedirect	Gets or sets a value that indicates whether the request should follow redirection responses.
	AllowWriteStreamBuffering	Gets or sets a value that indicates whether to buffer the data sent to the Internet resource.
	ConnectionGroupName	When overridden in a descendant class, gets or sets the name of the connection group for the request. (Inherited from WebRequest.)
	ContentLength	Gets or sets the Content-length HTTP header. (Overrides WebRequest. . :: . .ContentLength.)
	ContentType	Gets or sets the value of the Content-type HTTP header. (Overrides WebRequest. . :: . .ContentType.)
	ContinueDelegate	Gets or sets the delegate method called when an HTTP 100-continue response is received from the Internet resource.
	Credentials	Gets or sets authentication information for the request.
	DefaultMaximumResponseHeadersLength	Gets or sets the default for the MaximumResponseHeadersLength property.
	Expect	Gets or sets the value of the Expect HTTP header.
	HaveResponse	Gets a value that indicates whether a response has been received from an Internet resource.
	Headers	Specifies a collection of the name/value pairs that make up the HTTP headers. (Overrides WebRequest. . :: . .Headers.)
	HttpsAuthentCerts	Gets or sets the array of certificates used to authenticate HTTPS servers.
	IfModifiedSince	Gets or sets the value of the If-Modified-Since HTTP header.
	KeepAlive	Gets or sets a value that indicates whether to make a persistent connection to the Internet resource.
	MaximumAutomaticRedirections	Gets or sets the maximum number of redirects that the request follows.
	MaximumResponseHeadersLength	Gets or sets the maximum allowed length of the response headers.
	Method	Gets or sets the method for the request. (Overrides WebRequest. . :: . .Method.)
	ProtocolVersion	Gets or sets the version of HTTP to use for the request.
	Proxy	Gets or sets proxy information for the request. (Overrides WebRequest. . :: . .Proxy.)
	ReadWriteTimeout	Gets or sets a time-out in milliseconds when writing to or reading from a stream.
	Referer	Gets or sets the value of the Referer HTTP header.
	RequestUri	Gets the original Uniform Resource Identifier (URI) of the request. (Overrides WebRequest. . :: . .RequestUri.)
	SendChunked	Gets or sets a value that indicates whether to send data in segments to the Internet resource.
	Timeout	Gets or sets the time-out value in milliseconds for the GetResponse and GetRequestStream methods. (Overrides WebRequest. . :: . .Timeout.)
	TransferEncoding	Gets or sets the value of the Transfer-encoding HTTP header.
	UserAgent	Gets or sets the value of the User-agent HTTP header.

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Methods

	Name	Description
	AddRange(Int32)	Adds a byte range header to a request for a specific range from the beginning or end of the requested data.
	AddRange(Int32, Int32)	Adds a byte range header to the request for a specified range.
	AddRange(String, Int32)	Adds a Range header to a request for a specific range from the beginning or end of the requested data.
	AddRange(String, Int32, Int32)	Adds a range header to a request for a specified range.
	Dispose() () () ()	Releases the resources used by the HttpWebRequest. (Inherited from WebRequest.)
	Dispose(Boolean)	Releases the unmanaged resources used by the HttpWebRequest and optionally releases the managed resources. (Overrides WebRequest. . :: . .Dispose(Boolean).)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Performs clean up operations. (Inherited from WebRequest.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetRequestStream	Gets a Stream object to use to write request data. (Overrides WebRequest. . :: . .GetRequestStream() () () ().)
	GetResponse	Returns a response from an Internet resource. (Overrides WebRequest. . :: . .GetResponse() () () ().)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	Reset	Clears values for the HttpWebRequest instance.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

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 #ctor 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.

When you want to send data to the resource, the GetRequestStream method returns a Stream object to use to send data.

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

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.

Thread Safety

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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