When we implemented BookInventoryMockImpl in Chapter 5, The Book Inventory Bundle, we used a BundleActivator and the BookInventoryMockImplActivator to register it with the framework on start. It was actually a good idea then, because, while in validation mode, we've also inserted books on start.

As all we need to do is register the service, we'll move it to iPOJO. It's an easy thing to do.