Notification Services applications are based on a subscriber/subscription model.
The Key components in a Notification Services application are
Subscriber: A user or application that requests and receives the notification
Subscription: A request for information, delivery mechanism, and destination for requested notifications. For example change of a stock price.
Event: A piece of information, in which the subscriber is interested. For example as soon as a stock price has changed an event can be generated that's processed within SQLNS.
Notification: A message containing the information requested by the subscriber in the subscription.
SQLNS executes the following steps whenever it generates a new notification and sends it to registered subscribers:
.Subscribers create subscriptions with a subscription management application, such as an ASP.NET or Windows Forms front end.
.Subscription management is the only part of an SQLNS application where users or applications are actively involved in the process. You generate subscriptions using a managed assembly shipped with SQLNS.
.The Notification Application collects events, which are processed within the SQLNS application.
.SQLNS uses T-SQL statements to assign events to the subscriptions registered in the first step.
.SQLNS generates new notifications whenever it finds an assignment.
.A Formatter formats the new notification, and SQLNS delivers it through a delivery channel to the registered target device of the subscriber.