Initiates an asynchronous reverse lookup operation that has a specified state object. This overload receives notification, through a callback, of the identity of the event handler for this operation.
AsyncCallback that will receive the notification of the asynchronous operation completion.The IAsyncResult that identifies the posted asynchronous request.
When you use this overload, the callback specified in the callback parameter is invoked directly when the reverse lookup operation has completed; the LookupCompleted event is not raised. The other overloads of BeginReverseLookup rely on this component to raise the LookupCompleted event.
To use BeginReverseLookup, define an asynchronous callback method. BeginReverseLookup initiates an asynchronous reverse lookup operation; the DnsClient is notified, through a call to the callback method, when the reverse lookup operation is completed. The DnsClient can then access the reverse lookup status by calling EndReverseLookup.
Use this overload to associate information with the operation that will be preserved throughout the operation's lifetime. The event handler can detect this information by looking at the AsyncState of the IAsyncResult that is associated with the operation.
Note: The BeginReverseLookup method returns immediately, but the asynchronous operation is not completed until the event handler is called.
Because BeginReverseLookup is asynchronous, you can call it to receive the reverse lookup status without blocking the current thread of execution. To synchronously reverse lookup, use the ReverseLookup method.
Once an asynchronous operation completes, you can call BeginReverseLookup again in the event handler to keep receiving notifications.
The IAsyncResult that BeginReverseLookup returns identifies the asynchronous operation that the method call started. You can use this IAsyncResult throughout the lifetime of the operation, although you generally do not use it until EndReverseLookup is called. However, if you start several asynchronous operations, you can place their IAsyncResult values in an array and specify whether to wait for all operations or any operation to complete. In this case, you use the AsyncWaitHandle property of the IAsyncResult to identify the completed operation.
The state object associates state information with the operation. For example, if you call BeginReverseLookup multiple times to initiate multiple operations, you can identify each operation through a separate state object that you define.
You can also use the state object to pass information across process threads. If a thread is started but the callback is on a different thread in an asynchronous scenario, the state object is marshaled and passed back along with information from the event.
DnsClient Class | ComponentSpace.Dns Namespace | DnsClient.BeginReverseLookup Overload List