2-Tier Vs 3-Tier

January 13, 2008 at 5:15 am (Unit 1) (Middleware)

• Instead of Fat clients and fat servers these terms can be used.
• It is all about how you split the client/server applications into functional units.
• These functional units can be assigned to either the client or to one or more servers.
• The most typical functional units are:
  • User Interface
  • Business Logic and
  • the Shared Data
• In 2-tier, the application logic is either buried inside the User Interface on the client or within the database on the server (or both)
• 2-tier system examples: File Servers and Database Servers with stored procedure.
• In 3-tier, the application logic (or) process lives in the middle-tier, it is separated from the data and the user interface.
• 3-tier systems are more scalable, robust and flexible. In addition, they can integrate data from multiple sources.
• Examples: TP Monitors, Distributed Objects and the Web.

Different Meanings for 3-tier:

First:

tier 1 – Application in PC

tier 2 – Departmental Servers

tier 3 – Enterprise Servers

Then:

tier 1 – Partitions across client

tier 2 – local database

tier 3 – enterprise database

Now:

tier 1 – Client

tier 2 – Application Server

tier 3 – Database Server