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winrt class



Supports network communication that allows reading and writing streams using a WebSocket.


The StreamWebSocket class provides a stream-based abstraction of the message-based WebSocket protocol. This is useful for scenarios in which large files (such as photos or movies) need to be transferred. Using StreamWebSocket allows sections of a message to be read with each read operation, rather than requiring the entire message to be read in a single operation (as with MessageWebSocket).

StreamWebSocket only supports binary messages. For UTF-8 messages, MessageWebSocket must be used.

Handling exceptions

You must write code to handle exceptions when you call asynchronous methods on the StreamWebSocket class. Exceptions can result from parameter validation errors, name resolutions failures, and network errors. Exceptions from network errors (loss of connectivity, connection failures, and HTTP server failures, for example) can happen at any time. These errors result in exceptions being thrown. If not handled by your app, an exception can cause your entire app to be terminated by the runtime.

The Windows.Networking.Sockets namespace has a convenient helper method and enumeration for handling errors when using WebSockets. This can be useful for handling specific network exceptions differently in your app. An app can also use the HRESULT from the exception on parameter validation errors to learn more detailed information on the error that caused the exception.

For more information on possible exceptions and how to handle exceptions, see Handling exceptions in network apps.

Using StreamWebSocket on Windows Server 2012

On Windows Server 2012 and Windows Server 2012 R2, the Windows.Networking.dll that implements most of the classes in the Windows.Networking.Sockets namespace will fail to load unless the Media Foundation feature is enabled. As a result, apps that use StreamWebSocket and related WebSocket classes in the Windows.Networking.Sockets namespace will fail if the Media Foundation feature is disabled. Windows Server 2012 or Windows Server 2012 R2 installs with the Media Foundation feature disabled.

The Media Foundation feature can be enabled on Windows Server 2012 or Windows Server 2012 R2 using Server Manager or by entering the following text in a command prompt or a script:

dism /online /enable-feature /featurename:ServerMediaFoundation After the Media Foundation feature is enabled, the user is prompted to restart. Once the computer is restarted, classes for sockets and WebSockets in the Windows.Networking.Sockets namespace will work as expected.

Version history

Windows version SDK version Value added
1607 14393 ServerCustomValidationRequested



WebSockets, Handling exceptions in network apps, MessageWebSocket, StreamWebSocketControl, StreamWebSocketInformation, WebSocket sample, ControlChannelTrigger StreamWebSocket sample


internetClient, privateNetworkClientServer