IFWXIOCompletion interface

Applies to: desktop apps only

The IFWXIOCompletion interface includes a method that receives a notification from the Microsoft Firewall service when an asynchronous I/O send, sendto, or receive operation is completed on an IFWXSocket interface. These overlapped operations require that the filter implement this interface to carry out data pumping.

For more information about how the IFWXIOCompletion interface is used in application filters, see Filter Object Model.

When to implement

An application filter that initiates overlapped operations by calling the asynchronous methods on an IFWXSocket interface must implement this notification interface.


The IFWXIOCompletion interface inherits from the IUnknown interface. IFWXIOCompletion also has these types of members:

  • Methods


The IFWXIOCompletion interface has these methods.

Method Description

Receives a notification from the Firewall service when an asynchronous I/O operation that was initiated on an IFWXSocket interface completes.



When calling a method that begins an overlapped operation, the filter must pass a pointer to its IFWXIOCompletion interface to that method. The Firewall service calls CompleteAsyncIO on the IFWXIOCompletion interface of the filter when the overlapped operation completes.

Forefront TMG has two other notification methods for overlapped operations. The IFWXExternalIOCompletion::CompleteAsyncIO notification method is used for notification when a Windows overlapped operation completes, and the IFWXAcceptCompletion::CompleteAsyncAccept method is used for notification when the IFWXNetworkSocket::Accept method completes.


Minimum supported client

None supported

Minimum supported server

Windows Server 2008 R2, Windows Server 2008 with SP2 (64-bit only)


Forefront Threat Management Gateway (TMG) 2010



See also

Filter Interfaces






Build date: 7/12/2010