SQL Server 2005 Notification Services is what you would traditionally call “middle ware” or part of an application server. SQL Server is traditionally a “back end” or an infrastructure component to your architecture. SSNS is middleware provided by Microsoft as part of the SQL Server 2005 package. Microsoft has not traditionally provided a lot of middleware, but ever since the success of “Viper” or Microsoft Transaction Server (MTS), Microsoft has been providing more and more reliable and scalable middleware. Since SSNS is middleware and not part of the core database engine, SSNS is a separate setup option that is turned off by default when you initially set up your SQL Server 2005 server. You will need to select SSNS to install it at initial setup. 

If you choose to install SQL Server 2005 Notification Services, all of its components and support files install in a separate subdirectory (typically the \Notification Services subdirectory of your default SQL Server installation.). If you are like me and need to know what everything is, you can see by inspecting the subdirectory that SSNS is made up of a few components, the important ones are explained here:

microsoft.sqlserver.notificationservices.dll-this is the actual guts of Notification Services. A managed .NET assembly that contains the core code for SSNS and the built-in providers you use to retrieve data and create notifications and subscriptions.

NSService.exe-the executable shell of microsoft.sqlserver.notificationservices.dll used for running as a Windows Service. Each instance of NSService.exe runs as a Windows Service and can be managed by SQL Management Studio. Instances of NSService.exe are independent of SQL Server 2005 instances.

Providers-is the extensible framework that SSNS is built around: event providers, formatters and delivery protocol providers.

Nscontrol.exe-this is a utility program that is used when you compile your application and generates the SQL Server Database and objects that the Windows Service application uses to retrieve data and create notifications.

XML Schemas-When you generate a SSNS application, you use configuration files that are XML based. The schemas provided as part of the framework validate those documents.

Sample applications-more than most other tools, the community has used the sample applications to fully show the power of Notification Services. We will explore them as well.

This is good stuff. More later..