HttpListenerContext.AcceptWebSocketAsync Method (String, TimeSpan)

.NET Framework (current version)

Accept a WebSocket connection specifying the supported WebSocket sub-protocol and WebSocket keep-alive interval as an asynchronous operation.

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

Public Function AcceptWebSocketAsync (
	subProtocol As String,
	keepAliveInterval As TimeSpan
) As Task(Of HttpListenerWebSocketContext)


Type: System.String

The supported WebSocket sub-protocol.

Type: System.TimeSpan

The WebSocket protocol keep-alive interval in milliseconds.

Return Value

Type: System.Threading.Tasks.Task(Of HttpListenerWebSocketContext)

Returns Task(Of TResult).

The task object representing the asynchronous operation. The Result property on the task object returns an HttpListenerWebSocketContext object.

Exception Condition

subProtocol is an empty string


subProtocol contains illegal characters.


keepAliveInterval is too small.


An error occurred when sending the response to complete the WebSocket handshake.

This operation will not block. The returned Task(Of TResult) object will complete after the WebSocket connection has been accepted.

The size of the receive buffer is 16,385 bytes.

.NET Framework
Available since 4.5
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