In the 3 tier architecture there is Presentation/Web Layer, Service Layer and DB Layer. However in a recent project I worked on I saw a Manager Layer which is new to me. Can you please explain the difference between Service Layer/ Classes vs Manager Layer/ Classes?
Also please suggest some good books for learning 3 - tier architecture and related patterns. (For Java/ Java EE applications)
As per me : Manager Layer is a part of Service Layer in small applications. In complex applications we need to provide Manager Layer on the top of Service Layer.
Normally we don't need both in simple applications with a single UI, in this case we only manage Business Logic Layer / Manager Layer. In case of multiple UIs and Clients we divide Service Layer in 2 parts to handle UIs and to provide another services in application.