CENTRALISED

AND

CLIENT / SERVER DBMS

Topics To Be Discussed……………………….

(A) Centralized DBMS (i) Introduction

(ii) Advantages (ii) Disadvantages

(B) Client/Server DBMS (i) Introduction

(ii) Advantages (ii) Disadvantages

Centralized DBMS

The centralized database system consist of a single processor together with

its associated data storage devices and other peripherals. Database files

resides on centralized computer. Centralized computer may be a personal

computer, mini computer or mainframe computer depending upon the size

of enterprise. The application are run on the centralised computer. Multiple

users access the applications through simple terminals that have no

processing power of their own. Theuser interface is generally text-mode

screen.

Terminal 1

Terminal 1

Terminal 1

Terminal 1Physical Data

Advantages

Main advantages are :

1. The control over applications

2. Security is very good.

3. High reliable system

4. The incremental cost per user is very low.

5. Many functions such as update, query, backup control access are easier to

accomplish

Disadvantages

Main disadvantages of centralized database system are:

1. The failure of central computer blocks every user from using the system until

the system comes back.

2. The communication costs from the terminal to the central computer is a

3. matter of concern.

4. The users are not able to effectively manipulate data outside of standard

applications

Client/ Server DBMS

Client server architecture of database system has two logical components

client and server. Clients are generally personal computers or workstations

whereas server is a large workstations. The applications and tools of

DBMS run on one or more client platforms, while the DBMS software

reside on the ser ver. These server and client computers are connected into

a network. The applications and tools act as clients of the DBMS, making

request for its services. The DBMS processes thsese requests and returns

the results to the client. Client/Server architecture uses the graphical user

interface(GUI).

COMMUNICATION NETWORK

Physical Data

Client 1(Applications and Tools)

Client 2(Applications and Tools)

Client 3(Applications and Tools)

Client 4(Applications and Tools)

Server(DBMS Software)

Advantages

Advantages of client/Server computing are:

1. It can be used to develop highly complex multiuser application.

2. It offers expandability.

3. It allows connectivity with heterogeneous machines.

4. It provides better DBMS performance.

5. It avoids the requirement to write large number of redundant piece of code

dealing with database field validation and referential integrity.

6. It caters low cost and user friendly environment.

7. If the load on the database machine grows, the same application can be run

upgraded on machine provided

8. Parallel processing is possible. Response time and throughout thus be

improved.

9. A single database might be shared across several distinct client systems.

10. It provides better interfaces, high availability faster responses and overall

improved ease of use to the user.

Disadvantages

Disadvantages of client/server database system are:

1. Labour or programming cost is high in client/server environments,

particularly in initial phases.

2.There is a lack of management tools for diagnostics, performance,

monitoring and tuning and security controls for the DBMS client and

operating systems and networking environments.

THANKS