Data Base Architecture:

• A database architecture is represented as DBMS Design.
• Helps to design, develop, implement and maintain the database management system.
• Database system that can be divided into individual components which can be modified, changed, replaced and altered can be achieved by using DBMS Architecture.
• Components of database can also be understood by this architecture.
• Critical information can be stored in a database which helps to access the data quickly and securely.

Types of DBMS Architecture:

One Tier Architecture:

• It is a simplest architecture in which client, server, and database are in the same system.
• Database is directly available to the user in this architecture. User can directly use the DBMS.
• Any modification done in this architecture will be directly done on the database. It does not provide any tool for the users.
• This type of architecture is used for the local application development, where programmers can directly communicate with the database for speedier response.

Two Tier Architecture:

• It is a database architecture where the presentation layer runs on client and data is stored on a server called second tier.
• It is not exposed to user directly and provides security to the database.
• It provides direct and speed communication.
• It i s same as the basic client server. In this architecure applications on the client end can directly interact with database at the server side.
• At the client end the user interfaces and application programs are executed.
• Query processing and transaction management functions are done by the server.
• To communicate with the DBMS, client-side application establishes a connection with the server side.

Three Tier Architecture:

• Contains another layer between the client and server. In this architecture, communication between client to server is not possible.
• Client end application interacts with application server which further communicates with the database.
• In the application server, end user does not have any idea about the existence of the database
• The database also has no idea about any other user beyond the application.
• The 3-Tier architecture is used in case of large web application.

This architecture divides the entire system into a three inter related and independent modules.

Physical Level:

• In data, information about the location of database objects in the data store is kept in this level.
• Various DBMS users are unaware of the object locations.
• Information of data storage in secondary devices like disc, tapes  are provided in the level.

Conceptual Level:

• In this level data is represented in the form of database tables.
• Example student database contain STUDENT and COURSE Table which is visible to users but they don`t  know where data is stored.
• In this level, data is referred as logical schema, which describes the kind of data stored in the database.

External Level:

• Data in terms of conceptual level tables can be specified in this level.
• To cater the particular needs of user external level view is used.
• For Example, university FACULTY is interested in looking course details of students and STUDENTS are interested in looking at all details related to academics, accounts, courses and hostel details as well.
• Different user generates different views. So the main focus of external level is data abstraction.

Three Tier Architecture