Involve Services Layer

[alexbohomol]

We need service-layer

• to perform business-centric operations
• to provide business-ready workflows for controllers
• to decouple presentation layer from data-layer (as possible)

[alexbohomol]

• ContosoUniversity.Business project involved
• Introduced CoursesService implementing ICoursesService
• Refactored CourseController to use the ICoursesService instead of direct use of data-layer (UoW)

[alexbohomol]

• Introduced StudentsService implementing IStudentsService
• Refactored StudentController to use the IStudentService instead of direct use of data-layer (UoW)