Hi. Suppose I have an app (named MyApp) organized in the following way:

1. MyApp.WebUI : the user interface
2. MyApp.BOL : my entities, eg: Person, Departament, etc
3. MyApp.DAL : the data access layer

MyApp.WebUI references MyApp.BOL
MyApp.BOL references MyApp.DAL

In this scenario, if I want, I can access the DAL from the UI, thus breaking the 3tier aspect ... is there a way to avoid it? eg, to not let the UI access the DAL directly?