Where to write business rules/validations in ADF and why?

Validations like a field should have atleast 6 chars or it should have atleast one number and rest chars or any other kinds of validations can be coded in adf. There are different places where you can put validations depending on your requirement like when you want to fire them. Validations can be attribute level, entity level, transaction level etc- these all are declarative validations. They can also be coded inside a method, which will be programmatical validation. read less