How to: Add a Failure Notification Callback (Velocity)

[This topic is pre-release documentation and is subject to change in future releases. Blank topics are included as placeholders.]

Microsoft project code named "Velocity" allows your cache-enabled application to receive cache notifications. This topic describes how to add a failure notification callback to your application. Failure notifications are triggered when the cache client misses one or more cache notifications. For more information about cache notifications in general, see Cache Notifications (Velocity).

Similar to adding a callback for cache notifications, adding a callback for failure notifications involves two steps. First, create a method that should be invoked when a failure notification is triggered. The method you invoke with the failure notification must accept the same parameters as the DataCacheFailureNotificationCallback delegate. Second, add a callback for the failure notification using the AddFailureNotificationCallback method. Use the name of the method you created in the first step for the failureDelegate parameter.

Note

In order for your application to use notifications, you need to enable them on a named cache. Use the notificationsEnabled parameter with the New-Cache or Set-CacheConfig commands. For more information, see Cache Administration with PowerShell (Velocity).

How to add a failure notification callback

1. Create the method you want to be triggered by the failure notification. Make sure that the method you invoke with the failure notification accepts the same parameters as the DataCacheFailureNotificationCallback delegate.

2. Add a callback for the failure notification using the AddFailureNotificationCallback method. Use the name of the method that you want to invoke when the failure notification occurs in the failureDelegate parameter.

Example

The first step when adding a failure notification callback is to create a method that you want to be invoked by the notification. The method called by the notification must accept the same parameters as the DataCacheFailureNotificationCallback delegate. This example shows one example of a method that can be invoked by a failure notification.

'method invoked by failure notification "ndNotificationFailure"
Public Sub myNotificationFailureDelegate(ByVal myCacheName As String, _
    ByVal nd As DataCacheNotificationDescriptor)

    Console.WriteLine("===============================")
    Console.WriteLine("Invoked by failure notification")
    Console.WriteLine("===============================")
End Sub

//method invoked by failure notification "ndNotificationFailure"
public void myNotificationFailureDelegate(string myCacheName,
    DataCacheNotificationDescriptor nd)
{
    Console.WriteLine("===============================");
    Console.WriteLine(" Invoked by failure notification");
    Console.WriteLine("===============================");
}

The second step is to add a callback for the failure notification. In this example, a failure notification is created to invoke the method from the previous example.

'add failure notification callback
Dim ndNotificationFailure As DataCacheNotificationDescriptor
ndNotificationFailure = _
    myTestCache.AddFailureNotificationCallback(AddressOf myNotificationFailureDelegate)

//add failure notification callback
DataCacheNotificationDescriptor ndNotificationFailure
    = myTestCache.AddFailureNotificationCallback(myNotificationFailureDelegate);

See Also

Tasks

How to: Add a Cache Notification Callback (Velocity)
How to: Remove a Cache Notification Callback (Velocity)

Concepts

Cache Notifications Methods (Velocity)
Cache Administration with PowerShell (Velocity)