I am trying to estimate how long it will take to migrate a Classic ASP application to .NET and came across hundreds of COM functions written in VB 6.
A majority of these functions only do parameter validation and actually calls the SQL server. Is this something that should be replace with an ORM? (Linq, nHibernate, Entity Framework)... or should there be more to this picture?
The COM middle layer is not needed any more, you can have all the business logic inside classes in the same ASP.net project.
The good news is that you can use all this classes with little or no change, the only problem will be translating the DB calls (it depends how it is coded). If the ADO calls are wrapped inside internal functions, you only need to change the internal functions. If not, you will need to migrate all the methods.
Using an ORM will depend on this scenario, but I will say that it will add tons of more hours of work as you translate a perfectly valid SQL statement into a Linq or whatever statement.