Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
DownloadDataAsync Method (Uri)
Collapse the table of content
Expand the table of content

WebClient.DownloadDataAsync Method (Uri)

Downloads the resource as a Byte array from the URI specified as an asynchronous operation.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public void DownloadDataAsync(
	Uri address
)

Parameters

address
Type: System.Uri

A Uri containing the URI to download.

ExceptionCondition
ArgumentNullException

The address parameter is null.

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

An error occurred while downloading the resource.

This method retrieves the specified resource using the default method for the protocol associated with the URI scheme specified in address. The data is downloaded asynchronously using thread resources that are automatically allocated from the thread pool.

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 one of the DownloadData methods. When the download completes, the DownloadDataCompleted event is raised. Your application must handle this event to receive notification. The downloaded data is available in the Result property.

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

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

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.

NoteNote

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

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Show:
© 2015 Microsoft