nc-webservices-ws_service_close_channel_callback.md

UID	title	description	helpviewer_keywords	old-location	tech.root	ms.assetid	ms.date	ms.keywords	req.header	req.include-header	req.target-type	req.target-min-winverclnt	req.target-min-winversvr	req.kmdf-ver	req.umdf-ver	req.ddi-compliance	req.unicode-ansi	req.idl	req.max-support	req.namespace	req.assembly	req.type-library	req.lib	req.dll	req.irql	targetos	req.typenames	req.redist	ms.custom	f1_keywords	dev_langs	topic_type	api_type	api_location	api_name
NC:webservices.WS_SERVICE_CLOSE_CHANNEL_CALLBACK	WS_SERVICE_CLOSE_CHANNEL_CALLBACK (webservices.h)	Invoked when a channel is closed or aborted on an endpoint.	WS_SERVICE_CLOSE_CHANNEL_CALLBACK WS_SERVICE_CLOSE_CHANNEL_CALLBACK callback WS_SERVICE_CLOSE_CHANNEL_CALLBACK callback function [Web Services for Windows] webservices/WS_SERVICE_CLOSE_CHANNEL_CALLBACK wsw.ws_service_close_channel_callback	wsw\ws_service_close_channel_callback.htm	wsw	e2860015-219b-46be-921d-7ced0d95fc60	12/05/2018	WS_SERVICE_CLOSE_CHANNEL_CALLBACK, WS_SERVICE_CLOSE_CHANNEL_CALLBACK callback, WS_SERVICE_CLOSE_CHANNEL_CALLBACK callback function [Web Services for Windows], webservices/WS_SERVICE_CLOSE_CHANNEL_CALLBACK, wsw.ws_service_close_channel_callback	webservices.h		Windows	Windows 7 [desktop apps only]	Windows Server 2008 R2 [desktop apps only]													Windows			19H1	WS_SERVICE_CLOSE_CHANNEL_CALLBACK webservices/WS_SERVICE_CLOSE_CHANNEL_CALLBACK	c++	APIRef kbSyntax	UserDefined	WebServices.h	WS_SERVICE_CLOSE_CHANNEL_CALLBACK

WS_SERVICE_CLOSE_CHANNEL_CALLBACK callback function

-description

Invoked when a channel is closed or aborted on an endpoint. This callback is called right before we are about to close the channel.

For normal operation when service host is running and the client cleanly closed the channel, this implies that we have received a session closure from the client and we are about to close the channel.

The other scenario is when service host is going through an Abort Shutdown or during the processing of the message an unrecoverable error condition is met, as a result of this we attempt to abort and then close the channel. In this case as well right before the abort we will call upon this callback.

For session-based service contract, this notification signifies session tear down. Thus an application state scoped for the session can be destroyed within this callback.

-parameters

-param context [in]

The operation context.

-param asyncContext [in, optional]

Information on whether the function is getting invoked asynchronously.

-returns

This callback function does not return a value.

-remarks

The returned HRESULT is only used to see if the function is completing asynchronously. Failure or reporting failure through HRESULT does not in any way affects the service host infrastructure.

Irrespective of whether WS_SERVICE_ACCEPT_CHANNEL_CALLBACK competed successfully or not. This function will always be fired.

See also WS_SERVICE_ACCEPT_CHANNEL_CALLBACK which can be used by the application to associate state, and gets called when a channel gets accepted.

For an example implementation on how to use this callback for disassociating session state, see the session based calculator sample.

This callback is cancellable.

Examples

HRESULT CALLBACK FreeSessionCalculator (const WS_OPERATION_CONTEXT* context,
                                        const WS_ASYNC_CONTEXT* asyncContext)
{
     HRESULT hr = NOERROR;
     SessionfulCalculator* calculator = NULL;
     hr = WsGetOperationContextProperty (context, 
                                         WS_OPERATION_CONTEXT_PROPERTY_CHANNEL_USER_STATE, 
                                         &calculator, sizeof (SessionfulCalculator*), NULL);
     if (SUCCEEDED(hr) && (calculator != NULL))
     {                                                       
         delete calculator;
     }
     return NOERROR;
}