在c＃3层应用程序上创建PDF：哪一层？

Question

I am developing a C# 3-layer application: DAL ( Data Access Layer ), BLL ( Business Logic Layer ) and UI (User Interface). Now I need to create reports on PDF with data coming from DAL so I thought I should create a new class to do it, the question is, where do I put the class in terms of layering? (PS: I'll be using iTextSharp for the process)

The expected result is: User clicks a button on the form, and the new pdf appears on a specified folder.

It's an important project so I can't afford to mess up :(

Answer 1

It seems obvious that creating a report based on fetched data is a business logic task, so putting it in that layer initially seems a no-brainer.

You definitely do not want it in the UI in any case, and the DAL does not seem logical either. Let the BLL call the DAL and receive the data, then pass that data to a separate component in the BLL which can handle the job of generating the report. You can say that that component belongs to the BLL if you want, but I'd consider it more important to ensure it is as separate as possible from the rest of the system (hint: Hide it behind an interface, and only call it via that).