Concept of Three Tier Architecture

The advantage of three tier Architecture is code reusability. In starting live practice for three tier Architecture, there are three layers,

  1. BAL
  2. DAL
  3. UI (PAL)

BAL (Business Access Layer)

This layer defines a function or class to use to transfer data into Data Access Layer and Presentation Access Layer.

DAL(Data Access Layer)

This layer provides contents of logic to implement a program, for example, a  program to add, insert, or update; then all logic of this code is DAL Layer.

UI (PAL) User Interface Presentation Access Layer

The design purpose to use this Layeris simple --  to view all design layout from your program's webpage code.