What are system services?

System services are automatically installed when the Application Object Server is installed and are available when the AOS instance is running. They are written by Microsoft in managed code and hence they cannot be customized.

As mentioned, there are three system services, as follows:

• Metadata service

• Query service

• User session service

We will have a detailed discussion of these later in the chapter. We will not be able to go into every detail of all service operations, but it will be more than enough to get you started. Fortunately, for those who want to dig deeper, these services are well documented on MSDN.

A demo application

To demonstrate the usage of the different system services, we start with a demo application. The application is a Windows Forms application that contains the following elements:

• A combobox containing the Contoso Video Rental queries

• A DataGridView control to contain the resulting data

• Previous page and Next page buttons to provide paging of the result...