Each Microsoft Lync Controls application connects to Microsoft Lync Server 2010 using a single out-of-process connection to Microsoft Lync 2010. The application is either a Microsoft Windows Presentation Foundation (WPF) or Microsoft Silverlight application containing Lync Controls.

The application's connection to Lync 2010 is created by the first Lync Control instantiated by the application. This first control configures the layer between Lync 2010 and the application. The initial Lync Control automatically performs the following tasks.

• Adds Lync 2010 connectivity to a WPF or Silverlight application without requiring code-behind.

• Allows use of multiple interfaces between Lync Controls and Lync 2010 in a single application.

• Handles and exposes run-time errors.

• Ensures shut down of the layer between the Lync Controls application and Lync 2010.

Each subsequent Lync Control opened by the application uses the existing connection. To get the connection state, check the following properties.

• IsSignedIn property

• InitializationError property

• IsInResiliencyMode property

• InitializationErrorMessage property

For more information about checking connection state, see Troubleshooting Lync Control Applications .