Really the code for the ObjectDataSource select, update, delete,
insert methods should be contained in a separate class file in the
App_Code folder. When the ObjectDataSource executes these methods it
creates an instance of the class. If the code for these methods is
within the page code-behind then merely assigning the method names to
the ObjectDataSource will not work because it will expect a class name
reference.

You don't need a host project to do this. It works perfectly well
within a single web-site in the solution.