Type Of Application Architectures

Applications are developed to support the organisations in their business operations.Application receives input and accept it and process the data based on business rules and provides data as output.The functions performed by an application can be classified into three types

1. User Service
2. Business Service
3. Data Service

• User Service

This is regarded as the front end of the solution.This is also called presentation layer because it provides interactive user interface.

• Business Service

It controls the enforcement of business rules of the data of an organisation. Business rules encircle those practices and activities that define the behaviour of an organisation. Eg: an organisation decides that the credit limit of all client cannot exceed $200000. Business service layer sets rules or validations to pertain these functions.This means the back end does not receive incorrect data

• Data Service

It comprises the data and functions for manipulating this data.

These three layer form the base of models or architecture used in application development in an organisation.Applications can be

Single-Tier Architecture

Early we have discussed about the application architecture .On the basis of that we can explain what is single tier architecture?.In case of Single-tier architecture a single executable file handles all the functions relating to the user,business and data service layers.This is also called Monolithic application.

Some of early COBOL programs using this architecture.

Two-Tier Architecture

In case of two-tier architecture, an application is broadly divided into two

• Client:Implements the user interface
• Server:Storage of data

In case of this architecture the user and data services are either on the same machine or on the different machines.In two-tier architecture,the business layers are implemented in either of the following methods:

1. Fat Client

   In this type of method business service layer is combined with user service layer.Clients execute the presentation logic and enforce business logic.server stores data and process transactions.this is used when server is loaded with transaction processing activities and is not equipped to process business logic

2. Fat Server

   Here business service layer is combined with data service layer.As business service is stored on the server, most of the processing takes place on server.

3. Dividing business services between the user and data services

   You can also implemented in such a way that business services are distributed between user and data services.Here processing of business logic is distributed between data and user services.

Three-Tier Architecture

In case of three-tier architecture all the three layers reside separately,either on the same machine or on different machine which is entirely different from single-tier and two-tier architecture.

• The user interface interacts with business logic

• The business logic validates the data send by the interface and forwards it to the database if it confirms to the requirements

• The front end interacts with business logic in turn interacts with the database