Determining Plug-in Selection Order
The SelectionOrder property on the IWMSPlugin interface specifies and retrieves a zero-based index that is used by the server to determine the order in which plug-ins in a collection are selected for use. You can use this property to specify the default plug-in in a collection. For example, if you have multiple cache proxy plug-ins, you can specify the default plug-in by setting its SelectionOrder property to zero.
The selection order is particularly important for authentication plug-ins. For authentication plug-ins, the plug-in with the lowest selection order that uses an anonymous authentication scheme, such as the WMS Anonymous User Authentication plug-in, is used first. If anonymous authentication fails, the server will begin trying non-anonymous authentication plug-ins based on their selection order.
See Also
Reference
IWMSPlugin.SelectionOrder (C#)
IWMSPlugin.SelectionOrder (Visual Basic .NET)