I/O Event Callbacks

The framework can perform any one of the following actions when it receives an I/O request:

  • Place the request in a queue.

  • Call one of the driver’s callback functions without queuing the request.

  • Handle the request for the driver.

  • Forward the request to the default I/O target.

  • Fail the request.

The action that the framework performs depends on the type of request, the configuration of the driver’s queues, and the type of driver. Drivers should implement the I/O event callbacks and configure their queues so that WDF handles each type of request in a manner that is appropriate for the request and the device.

File Objects for I/O

From the point of view of a user-mode application, all I/O takes place through a file handle. From the point ...

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