DBMS Architecture Lecture Notes

Centralized DBMS Architecture

• Early Systems: Mainframe Computers

  • Used to process all system functions
  • Users accessed via computer terminals (display only, no processing capability)
  • Processing done remotely; results displayed on terminals
  • Network connection between terminals and mainframe

• Evolution with Hardware Cost Reduction

  • Terminals replaced by personal computers and workstations
  • Early DBMS mirrored display terminal setup but centralized
  • All processing on one machine; display info sent to terminals

• Shift to Client-Server Architecture

  • Utilized processing power on user side
  • Led to development of client-server models

Client-Server Architecture

Overview

• Purpose: Manage large number of PCs, workstations, printers, file servers etc., via a network
• Specialized Servers: Servers dedicated to specific functionalities (e.g., file servers, printer servers)
• Client Machines: Provide user interfaces to access server resources
• Diagrams: Illustrate logical and physical levels

Client-Server Interaction

• Client: User machine with interface capabilities and local processing
  • Requests additional functionalities from servers
• Server: Provides services like file access, printing, database access

Types of Client-Server Architectures

Two-Tier Architecture

• Initial Setup: RDBMS started as centralized; evolved with client-server models
• Division of Components:
  • Client Side: User interfaces, application programs
  • Server Side: Query and transaction functionality
  • Server termed as Query Server/Transaction Server or SQL Server
• Connectivity:
  • ODBC: API for client programs to call DBMS on server side
  • JDBC: Java API for accessing DBMS
• Advantages:
  • Simplicity
  • Compatibility with other systems

Three-Tier Architecture

• Emergence: Driven by WWW, changing client-server roles
• Intermediate Layer: Between client and database server
  • Application server/Web server
  • Stores rules for data access
  • Processes client requests, sends database commands
  • Channels processed data to client, making it presentable (GUI format)
• Components:
  • User Interface (Client)
  • Application Rules (Intermediate Layer)
  • Data Access (Database Server)

Conclusion

• Discussed Centralized DBMS Architecture
• Explored Client-Server Architectures (Two-Tier and Three-Tier)
• Key Concepts Understanding: Centralized DBMS, Client-Server Models, ODBC, JDBC

End of Lecture