Architecture in DBMS : client server architecture

 Database System Architecture

Client Server Architecture-

The client server architecture was developed to deal with computing environments where a large number of pcs worth stations, file servers, printers, database servers, web servers and the other equipment are connected together via a network. The idea is to define. Specialized server with specific functionalities. 

       The concept of client server architecture assumes an underlying framework that consists of many PCs and workstation, as well as a smaller number of mainframe machines connected via local area network and other type of computer networks. 

A client in this framework is typically a user machine that provides user interface capabilities and local processing. While when a client require access to additional functionality, such as database access, that does not exist at the machine it connect to server that provide the needed functionality. 

A server easy machine that can provide service to the client machine, such as printing, archiving of database access. The client server architecture is increasing being incorporated into commercial DBMS packages in relational DBMS many of which started a centralized system. The system components that user first move to the client side were the user interface and application programs. 

Because SQL provided a standard language for RDBMS, it created a logical dividing point between client and server. Hence the query transaction functionality remained at the server side in such a literature. The server is often called a query server of transaction, server because it provides these two functionalities.

    In such a client server architecture, the user interface program and application programs common at the client side, where DBMS access is required, the program establishes a connection to the DBMS, which is on the server side. And once of the connection is created, the client program can communicate with the DBMS, a standard called open database connectivity, (ODBC) provides an application programming interface(API), which allow client side program to call the DBMS as long as both client and server machine have the necessary software installed.

Database functionality can be broadly divided into 2 parts:

The front-end and the back-end. The back-end manages excess structure, query evaluation and optimization concurrency control and recovery. The front-end of a database system consists of tools such as form, report, writers and graphical user interface facilities. The interface between the front-end and the back-end is through SQL or through an application program.

THREE LEVEL ARCHITECTURE OF DATABASE SYSTEM

The goal of the three schema architecture is to separate the user application and the physical database in this architecture, schemas can be defined at three levels:

Physical Level or Internal Level -

This is the lowest level of abstraction and describe how the data actually stored. The physical level described complex, low level data structure and details.

Internal level describes physical storage structure of the database it uses physical data model, and it describes complete detail of data storage and access path of the database. The internal view is expressed by the internal schema, which contain the information of a stored record.

Logical Level or Conceptual Schema -

This is the next higher level of abstraction, and it describes what data stored in the database and what relationship exists among those data, the logical level, thus described the entire database in terms of a small number of relatively simple structures.

Conceptual schema describes the structure of hold database. It describes entities, data types, relationship, operations and constraints, etc. Conceptual schemas, hide details of physical storage. 

View Level or External Level -

This is the highest level of abstraction. Describe only part of the entire database, even though the logical levels uses simpler structure, complexity remains because of the variety of information is stored in the large database. The view level of abstraction exists to simplify their interaction with the system. The system may provide many views for the same database.

External schema describe the part of the database that a particular user group is interested in and hide the rest of the database from the user group.

Advantages of three level architecture of DBMS-

The DBMS serves as the intermediately between the user and the database. The database structure itself is stored as a collection of files, and the only way to access the data in those file is through the DBMS. The DBMS receives all application requests and translate them into the complex operations required. To fulfill those requests, the DBMS hides much of the database internal complexity from the applications programs and users.

The different advantages of DBMS are as follows:

1. Improved Data Sharing-

The DBMS help create an environment in which end user have better access to more and better manage data. Such access makes it possible for end user to respond quickly to changes in their environment.

2. Improved Data Security-

The more users access the data, the greater the risk of data security breaches. Corporations invest considerable amount of time, effort and money to assure that corporate data are used properly. Our DBMS provides a framework for better. Enforcement of data privacy and security policies.

3. Better Data Integration-

Wider access to bail many startup promotes an integrated view of the organizations operation and a clear view of the big picture. It become much easier to see how action it one segment of the company affect other segments.

4. Minimize Data Inconsistency-

Data inconsistency exists when different version of the same data appear in different places. For example, data inconsistency exists when a company sales department store a sales representative name and Bill Brown and the company's personal department is stored that same person name as William G Brown, or when the company regional sales. Office shows the price of a product as $45.95. and its national sales office shows the same products, prices, $43.95, the probability of the data inconsistency is greatly reduced in a properly designed database.

5. Improved Data Access-

The DBMS make it possible to produce quick answer to ad hoc queries from a database Perspective, a query is a specific request issued to the DBMS for data manipulation. For example, end-users when dealing with large amount of sales data might want quick answer to questions (ad hoc queries), such as:

What was the dollar volume of sales by product during the past six months?

6. Improved Decision Making-

Better managed data and improved data access make it possible to generate better quality information on which better decisions are based. The quality of the information generated depends on the quality of the underlying data. Data quality is a comprehensive approach to promoting the accuracy. Validity and timeless of the data. While the DBMS does not guarantee data quality, it provide a framework to facilitate data quality initiatives. 

7. Increased End-User Productivity-

The availability of data combined with the tools that transform data into usable information empowers and user to make quick informed decision that can make the difference between success and failure in the global economy.

Conclusion-

These were some of the point discussed in the post-  Database system architecture and  its type.

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