app/model/README.md

   1 This is the model LAYER. In here there should probably be three factory classes:
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   3 BusinesObjectFactory - this knows how to build a business object.
   4 DataMapperFactory - this knows how to build a datamapper. DataMappers populate/save business objects by communicating with the database
   5 ServiceFactory - to build services. Services facilitate communication between business objects and datamappers.
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   8 Since the model is a LAYER in this application there is no one model class, instead we pass the same instance of the ServiceFactory to views
   9 and controllers. The services contain the DataMapperFactory and BusinessObjectFactory.