DDEX Data Connection UI
Visual Studio provides data connection user interface (UI) to enable point-and-click connectivity to data sources. Data connection UI comprises three dialog boxes:
Data Source dialog box, which allows the user to select or change a data source and the associated data provider.
Data Connection dialog box, which allows the user to specify or change data connection information.
Advanced Connection Properties dialog box, which provides a property grid in which to edit or apply connection property values.
About Data Connection UI
The assembly Microsoft.VisualStudio.Data.Services.DLL provides the base interfaces that need to be implemented to supply data connection UI that works inside Visual Studio.
While Visual Studio is the primary consumer of this data connection UI, it is also consumed by a selection of other Microsoft products. In these cases, where Microsoft.VisualStudio.Data.Services.DLL is not shipped, another assembly, Microsoft.Data.ConnectionUI.DLL, supplies IDataConnectionUIControl and IDataConnectionProperties interfaces that should be implemented by third parties. The IVsDataConnectionUIControl and IVsDataConnectionProperties interfaces are implemented in the DDEX Framework classes, so a DDEX provider implementation from these classes will automatically inherit the ability to work in other Microsoft products.
To summarize:
To handle data connection UI inside of Visual Studio, you need a reference to Microsoft.VisualStudio.Data.Services.DLL, which provides access to the IVsDataConnectionUIControl and IVsDataConnectionProperties interfaces. This provides the support required for non-Visual Studio scenarios automatically.
To handle data connection UI outside of Visual Studio, you need to implement the IDataConnectionUIControl and IDataConnectionProperties interfaces directly, which are defined in Microsoft.Data.ConnectionUI.DLL.
If you intend to handle both scenarios, or if you are working inside of Visual Studio presently but intend in future versions to add a non-Visual Studio scenario, you should follow item #1, above. Implementing the IVsDataConnectionUIControl and IVsDataConnectionProperties interfaces implements the corresponding interfaces without additional effort.