Internal Events

Article
09/04/2009

You can use event notices to respond to changes in the state of the server. You can obtain event notices internally by using either the IWMSEventNotificationPlugin interface or the IWMSEventAuthorizationPlugin interface. You can use the WMS WMI Event Handler plug-in included with Windows Media Services to obtain an event notice externally. For more information, see External Events.

To retrieve event notices internally, you must use one of the event notification and authorization plug-ins included with Windows Media Services, or create your own. An event notification plug-in indicates the event notices that it must receive by implementing the GetHandledEvents method on the IWMSEventNotificationPlugin interface. An authorization plug-in indicates the event notices that it must receive by implementing the GetAuthorizedEvents method on the IWMSEventAuthorizationPlugin interface.

When a registered event occurs, the server calls either the OnEvent method on the IWMSEventNotificationPlugin interface or the AuthorizeEvent method on the IWMSEventAuthorizationPlugin interface and fills a WMS_EVENT structure to identify the type of event that occurred. The server also fills in a command context, user context, and presentation context.

The WMS_EVENT structure contains a WMS_EVENT_TYPE enumeration type.

struct WMS_EVENT
{
    long Version;
    enum WMS_EVENT_TYPE Type;
    long hr;
};

The following table identifies the internal event notices that can be sent by the server. The value column lists the numeric value associated with each event. You must supply the numeric value when you use Visual Basic Scripting Edition (VBScript). The notification event and authorization event columns indicate whether a notification plug-in or an authorization plug-in can subscribe to the event. Authorization events that are associated with read/write access require that an authentication plug-in be enabled before authorization can occur. This is indicated in the table by the "Authentication required" column. The event notices in the following table are members of the WMS_EVENT_TYPE enumeration type.

Event	Value	Notification event	Authorization event	Authentication required
WMS_EVENT_UNKNOWN_EVENT	0	Yes	No	n/a
WMS_EVENT_CONNECT	1	Yes	Yes	No
WMS_EVENT_DISCONNECT	2	Yes	No	n/a
WMS_EVENT_BEGIN_USER_SESSION	3	Yes	Yes	No
WMS_EVENT_END_USER_SESSION	4	Yes	No	n/a
WMS_EVENT_LOGICAL_URL_TRANSFORM	5	No	Yes	No
WMS_EVENT_PHYSICAL_URL_TRANSFORM	6	No	Yes	No
WMS_EVENT_DESCRIBE	7	Yes	Yes	Yes
WMS_EVENT_OPEN	8	Yes	Yes	Yes
WMS_EVENT_SELECT_STREAMS	9	Yes	Yes	Yes
WMS_EVENT_INITIALIZE_PLAYLIST	10	No	Yes	No
WMS_EVENT_PLAY	11	Yes	Yes	Yes
WMS_EVENT_PAUSE	12	Yes	No	n/a
WMS_EVENT_STOP	13	Yes	No	n/a
WMS_EVENT_CLOSE	14	Yes	No	n/a
WMS_EVENT_SET_PARAMETER	15	Yes	No	n/a
WMS_EVENT_GET_PARAMETER	16	Yes	Yes	Yes
WMS_EVENT_VALIDATE_PUSH_DISTRIBUTION	17	Yes	Yes	Yes
WMS_EVENT_CREATE_DISTRIBUTION_DATA_PATH	18	Yes	No	n/a
WMS_EVENT_DESTROY_DISTRIBUTION_DATA_PATH	19	Yes	No	n/a
WMS_EVENT_LOG	20	Yes	No	n/a
WMS_EVENT_SERVER	21	Yes	No	n/a
WMS_EVENT_PUBLISHING_POINT	22	Yes	No	n/a
WMS_EVENT_LIMIT_CHANGE	23	Yes	No	n/a
WMS_EVENT_LIMIT_HIT	24	Yes	No	n/a
WMS_EVENT_PLUGIN	25	Yes	No	n/a
WMS_EVENT_PLAYLIST	26	Yes	No	n/a
WMS_EVENT_CACHE	27	Yes	No	n/a
WMS_EVENT_REMOTE_CACHE_OPEN	28	Yes	No	n/a
WMS_EVENT_REMOTE_CACHE_CLOSE	29	Yes	No	n/a
WMS_EVENT_REMOTE_CACHE_LOG	30	Yes	No	n/a

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Internal Events

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