FileWebRequest.BeginGetRequestStream Method (AsyncCallback, Object)

 

Begins an asynchronous request for a Stream object to use to write data.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public override IAsyncResult BeginGetRequestStream(
	AsyncCallback callback,
	object state
)

Parameters

callback
Type: System.AsyncCallback

The AsyncCallback delegate.

state
Type: System.Object

An object that contains state information for this request.

Return Value

Type: System.IAsyncResult

An IAsyncResult that references the asynchronous request.

Exception Condition
ProtocolViolationException

The Method property is GET and the application writes to the stream.

InvalidOperationException

The stream is being used by a previous call to BeginGetRequestStream.

ApplicationException

No write stream is available.

WebException

The FileWebRequest was aborted.

The BeginGetRequestStream method starts an asynchronous request for a stream used to send data to a file system resource. The callback method that implements the AsyncCallback delegate uses the EndGetRequestStream method to return the request stream.

The following code example uses BeginGetRequestStream to make an asynchronous request for a Stream object.


public class RequestDeclare
{
	 public FileWebRequest myFileWebRequest;	
	 public String userinput;

		public RequestDeclare()
	{
		myFileWebRequest = null;
	}
}

class FileWebRequest_reqbeginend
{
	public static ManualResetEvent allDone = new ManualResetEvent(false);

	static void Main(string[] args)
	{
	  if (args.Length < 1)
	  {
  		    Console.WriteLine("\nPlease enter the file name as command line parameter:");
		       Console.WriteLine("Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>\nExample:FileWebRequest_reqbeginend shafeeque/shaf/hello.txt");

	  }  
	  else
	  {

	    try
		 {

		      // Place a webrequest.
		      WebRequest myWebRequest= WebRequest.Create("file://"+args[0]);

    	      // Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.		
		      RequestDeclare requestDeclare = new RequestDeclare();
		      requestDeclare.myFileWebRequest = (FileWebRequest)myWebRequest;
		      // Set the 'Method' property of 'FileWebRequest' object to 'POST' method.
		      requestDeclare.myFileWebRequest.Method="POST";
		      Console.WriteLine("Enter the string you want to write into the file:");
		      requestDeclare.userinput = Console.ReadLine();

		      // Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
		      IAsyncResult r=(IAsyncResult) requestDeclare.myFileWebRequest.BeginGetRequestStream(new AsyncCallback(ReadCallback),requestDeclare);			
		      allDone.WaitOne();

		      Console.Read();
	    }
	    catch(ProtocolViolationException e)
	    {
	          Console.WriteLine("ProtocolViolationException is :"+e.Message);
	    }
	    catch(InvalidOperationException e)
	    {
		   	Console.WriteLine("InvalidOperationException is :"+e.Message);
	    }
	    catch(UriFormatException e)
	    {
			Console.WriteLine("UriFormatExceptionException is :"+e.Message);
		 }
	 }
	}

	private static void ReadCallback(IAsyncResult ar)
	{	

     try
  	  {

		  // State of the request is asynchronous.
		  RequestDeclare requestDeclare=(RequestDeclare) ar.AsyncState;
		  FileWebRequest myFileWebRequest=requestDeclare.myFileWebRequest;
		  String sendToFile = requestDeclare.userinput;

		  // End the Asynchronus request by calling the 'EndGetRequestStream()' method.
		  Stream readStream=myFileWebRequest.EndGetRequestStream(ar);

		  // Convert the string into byte array.

		  ASCIIEncoding encoder = new ASCIIEncoding();
		  byte[] byteArray = encoder.GetBytes(sendToFile);

		  // Write to the stream.
		  readStream.Write(byteArray,0,sendToFile.Length);
		  readStream.Close();
		  allDone.Set();

		  Console.WriteLine("\nThe String you entered was successfully written into the file.");
   	  Console.WriteLine("\nPress Enter to continue.");	


        }
       catch(ApplicationException e)
	  {
		  Console.WriteLine("ApplicationException is :"+e.Message);
	  }				

	}

.NET Framework
Available since 1.1
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