DownloadStringAsync Method (Uri, Object)
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WebClient::DownloadStringAsync Method (Uri^, Object^)


Downloads the specified string to the specified resource. This method does not block the calling thread.

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

[HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)]
void DownloadStringAsync(
	Uri^ address,
	Object^ userToken


Type: System::Uri^

A Uri containing the URI to download.

Type: System::Object^

A user-defined object that is passed to the method invoked when the asynchronous operation completes.

Exception Condition

The address parameter is null.


The URI formed by combining BaseAddress and address is invalid.


An error occurred while downloading the resource.

The resource is downloaded asynchronously using thread resources that are automatically allocated from the thread pool.

After downloading the resource, this method uses the encoding specified in the Encoding property to convert the resource to a String. This method does not block the calling thread while downloading the resource. To download a resource and block while waiting for the server's response, use the DownloadString method. When the download completes, the DownloadStringCompleted event is raised. Your application must handle this event to receive notification. The downloaded string is available in the Result property.

You can use the CancelAsync method to cancel asynchronous operations that have not completed.

If the BaseAddress property is not an empty string ("") and address does not contain an absolute URI, address must be a relative URI that is combined with BaseAddress to form the absolute URI of the requested data. If the QueryString property is not an empty string, it is appended to address.

This method uses the RETR command to download an FTP resource. For an HTTP resource, the GET method is used.


This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

.NET Framework
Available since 2.0
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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