Spring, Hibernate, Java EE in the 3 Tier architecture

Question

I need to get a start as to where I put those technologies in the 3 Tier architecture: This is what I have...

• presentation layer: HTML, JSP

• app. layer: Java EE, Spring

• data access layer: Hibernate, PostgreSQL database

Answer 1

You are mixing Tier and Layer which makes things pretty confusing, especially for yourself! If your question is about layers, then ask a question about layers.

Anyway, let me try to clarify...

In a Three Tier architecture, the Tiers consist of:

• the Client Tier (or Presentation Tier),
• the Business Tier (or Middle Tier or Logic Tier or Application Tier, etc),
• the Enterprise Information Systems (EIS) Tier (or Data Tier).

And here are the typical layers of a multi layered application:

• the Presentation Layer: Servlet/JSP
• the Service Layer: Spring Services + Spring Transactions or EJB Session Beans
• the Domain Layer: POJOs
• the Data Access Layer: Hibernate/JPA
• the Physical Layer: Database, LDAP, file system, etc.

Hibernate would be part of the Data Access Layer (but PostgreSQL is part of the Physical Layer).

The Presentation, Service, Domain, Data Access Layers map to the Business Tier. The Physical Layer maps to the Data Tier.

Answer 2

Yes, I would put Hibernate in the data access layer. In fact the 3rd layer is the "Data layer" and not the data access layer, maybe this confuses you. So everything that's business logic related goes into the app (or business) layer.