Edytuj

Udostępnij za pośrednictwem

Binding an Event Filter with a Logical Consumer

  • Artykuł

After you create the logical event consumer and the event filter you must link them, which registers the logical consumer to receive notification about the events specified by the filter.

The following procedure describes how to bind an event filter with a logical consumer.

To bind an event filter with a logical consumer

  1. Create an instance of the __FilterToConsumerBinding system class in the WMI repository.

    The __FilterToConsumerBinding class is an association class that links the event filter instance and the logical consumer instance together through the Filter and Consumer reference properties. For more information, see Declaring an Association Class.

  2. Set the Filter property to the instance of your filter.

  3. Set the Consumer property to the instance of your logical consumer.

  4. Set the DeliverSynchronously property to determine the type of delivery you want.

    The DeliverSynchronously property determines when WMI delivers event notifications synchronously or asynchronously. Setting this property to TRUE requests a synchronous delivery. Use synchronous delivery only when the permanent consumer can process events within approximately 100 microseconds.

    Note

    Because the callback to the sink might not be returned at the same authentication level as the client requires, it is recommended that you use semisynchronous instead of asynchronous communication. For more information, see Calling a Method.

     

  5. When unregistering your logical event consumer, ensure you delete the __FilterToConsumerBinding instance.

    Each __FilterToConsumerBinding instance represents a registration for a specific event notification. When you delete a binding, WMI deactivates the registration. You might have to delete the logical consumer and event filter instances to deactivate registration, depending on the implementation.

The following code example shows you a __FilterToConsumerBinding instance that associates an instance of an ActiveScriptEventConsumer class with a specific event filter (the instance of the event consumer was created in the Creating a Logical Consumer topic, and the event filter was created in the Creating an Event Filter topic).

instance of __FilterToConsumerBinding
{
    Filter = $FILTER;
    Consumer = $CONSUMER;
    DeliverSynchronously=FALSE;

    // this is the Administrators SID in array of bytes format
    CreatorSID = {1,2,0,0,0,0,0,5,32,0,0,0,32,2,0,0}; 
};

Two consumers, ActiveScriptEventConsumer and CommandLineEventConsumer, will not work unless their creator is a member of the local Administrators group.

: When an administrator creates a subscription, his SID is not used for the CreatorSID property, but the SID of the local Administrators group is used instead. Therefore, instances can be created by different administrators and the subscription will still work. For more information, see Receiving Events Securely.

When a filter is bound to a logical consumer the event is recorded by Event Tracing for Windows (ETW). For more information, see Tracing WMI Activity.

Receiving Events at All Times