I'm in the middle of writing a custom DTS transform to perform fast key lookups for dimensioning facts as they are streamed into the database. I'll post more when I have completed it but for now I'm disappointed to find out that there is no way to provide any sort of user interface beyond the standard property dialog.

This strikes me as a major oversight on Microsoft's part considering they managed to do it for custom tasks. I have to question why they didn't add the capability. A number of the built in transforms have custom dialogs that appear when you click the properties button so it must be possible.

There are two reasons that I can think of. The first is that there is a way to provide custom transform dialogs and this is how they implement their own transform UIs but the interface is undocumented. The second is that the main transform task also implements all the UIs for the transforms.

Subscribers to the "evil empire" theory will probably favour the first reason. I can't agree because keeping the interface private would only benefit Microsoft if they were selling their own custom transforms. If the second is true then they are responsible for some pretty poor design. This is especially true because they managed to get the design right for custom tasks. The teams can't be that big that communication breaks down so it must be those little private offices they all have.

Maybe someone on the DTS team can enlighten me?