Creating a Notification Port

Applications perform the following steps to create a notification port.

1. Spawn a separate thread to create and monitor the port.

2. Call CreateClusterNotifyPort. For the initial call, set hChange to INVALID_HANDLE_VALUE so that a new handle will be created. Subsequent calls can specify hChange to add more events to the port.

3. Set the dwFilter parameter to one or more events of interest, using the OR operator ( | ) to specify multiple events. For example, if an application should be informed when there is any change to the cluster'sresource types, it would set dwFilter as follows:

   dwFilter = CLUSTER_CHANGE_RESOURCE_TYPE_ADDED | CLUSTER_CHANGE_RESOURCE_TYPE_DELETED;

4. Set the dwNotifyKey parameter to a value that identifies the events specified by dwFilter. When you retrieve events from the port, all events of type <dwFilter> will be "flagged" with a value of <dwNotifyKey>. You can use dwNotifyKey like an index to differentiate different event types in the same port. For example, the following code fragment creates a notification port for monitoring resource and cluster database events such that any resource-related event will return a dwNotifyKey value of ResourceEvents, and any cluster database event will return a dwNotifyKey value of DatabaseEvents:

   HCHANGE hChange;
   
   DWORD ResourceEvents = CLUSTER_CHANGE_RESOURCE_ADDED    |
                          CLUSTER_CHANGE_RESOURCE_DELETED  |
                          CLUSTER_CHANGE_RESOURCE_PROPERTY |
                          CLUSTER_CHANGE_RESOURCE_STATE;
   
   DWORD DatabaseEvents = CLUSTER_CHANGE_REGISTRY_ATTRIBUTES |
                          CLUSTER_CHANGE_REGISTRY_NAME       |
                          CLUSTER_CHANGE_REGISTRY_SUBTREE    |
                          CLUSTER_CHANGE_REGISTRY_VALUE;
   
   hChange = CreateClusterNotifyPort( (HCHANGE)INVALID_HANDLE_VALUE,
                                      hCluster,
                                      ResourceEvents,   // dwFilter
                                      ResourceEvents ); // dwNotifyKey
   
   hChange = CreateClusterNotifyPort( hChange,
                                      hCluster,
                                      DatabaseEvents,
                                      DatabaseEvents );