SOFTWARE ENVIRONMENTS

ENVIRONMENTS

Environment: - Environment is a combination of three layers

a.    Presentation layer

b.    Business layer

c.    Data base Layer

System: The application installed in to an environment combinable called as system.

1. Presentation Logic: The logic that is used for viewing application is known as presentation logic
2. Business Logic: - The logic that is used for performing the operations on the application is known as business logic.
3. Data Base Logic: - The logic that is used for sharing and retrieving the data is known as database logic.

Types of Environment:

There are four types of environments

1. Stand-alone environment or One-tier environment
2. Client –server environment or Two-tier Architecture
3. Web environment or Three-tier Architecture
4. Distributed environment or N-tier Architecture

a.    Stand Alone environment: -

 In this type of environment all the three layers that is presentation layer, Business layer& Database layer will be present in al single tier. This type of environment is suitable for single user application.

One-Tier Architecture

                            PL

                            BL            ÞOne tier Architecture
                            DBL

 

b.    Client –server environment:

In this type of environments there will be two tiers, one tier is for clients and other tier is for database servers. The presentation layer and the business layer will be present in each and every client. The database layer will be present in the database server. This type of environment is suitable for multi user application in a single or a limited area.

Two tier Architecture

 

                            PL+BL                                DBL
                           

                             PL+BL

                                  

                                PL+BL

                                Clients                              Server

c.    Web environment: - In his type of environment three tiers will be there. One is for client’s the middle one is for application server and the other one is for database servers. Presentation layer will be present at clients, Business layer will be present in the application server, and database layer will be present at the database servers. This type of environment is suitable for the applications that are used all over the world by limited number users

Three-tier Architecture:

 

               PL

                                                                                                      DBL

BL

                    PL

 

                                                                                                       DBL

Appl Server

Database server

Clients

                    PL

Web server: -

                   It is software, which provides web services to the clients.

E.g.: - Internet Information service (IIS).

Example for Application servers: Tom pact, Web logic, web sphere etc..,

d.   Distributed environment: -

It is similar to the web environment but the number of application servers are increased and represented in individual tiers in order to distribute the business logic so that the logic will be distributed.

Ws

N-tier Architecture:

 

PL                                                                                                    DBL

 

                                 BL                            BL                        BL

PL

 

PL

PL

Database server

Apl server2

Apl server2

Apl server1

Clients