Plasma should be able to have different themes for same data.For example there should be 10 different Clocks, while all of them are showing one thing: Time. So Plasma Provides Data Engines. Data Engines will provide Data for Plasmoids.

So to have a Clock Plasmoid:

Plasma --> Time Data Engine

                                          |---> Clock Plasmoid 1
                                          |---> Clock Plasmoid 2