2 Tier and 3 Tier Architecture in DBMS

Introduction

• Importance: Commonly asked in theory exams and crucial for CSE students.
• Real-life examples provided.

2 Tier Architecture

• Definition: Two layers - Client Layer and Database Server.
• Functionality:
  • Client Layer: Interface on client machine helps fetch data from the database server using APIs (e.g., JDBC-ODBC).
  • Communication: May occur over different locations.
  • Application Program: Written in any language, executed on the server.
• Examples:
  • Indian Railways: Ticket reservation through client machines at stations.
  • Banks: Transactions processed via client machines at bank branches.
• Advantages:
  • Simplicity: Easy maintenance with limited, authorized clients.
• Disadvantages:
  • Scalability: Not suited for large numbers of users accessing data 24/7.
  • Security: Direct client-database interaction poses vulnerability risks.

3 Tier Architecture

• Definition: Three layers - Application Layer (Client), Business Layer, and Data Layer.
• Functionality:
  • Client Layer: Normal user interface, e.g., IRCTC website.
  • Business Layer: Processes queries, reduces load on database server.
  • Data Layer: Stores data, interacts only through the business layer.
• Advantages:
  • Scalability: Business layer handles multiple users effectively.
  • Security: User does not directly interact with data; interaction is through the business layer.
• Disadvantages:
  • Maintenance: More complex due to additional layer.

Comparison and Use Cases

• 2 Tier Architecture: Used in physical locations like banks and railway stations.
• 3 Tier Architecture: Used in web applications, emphasizing security and scalability.

Conclusion

• 3 Tier Architecture is more prevalent due to its adaptability to modern user demands for secure, scalable, and always-available data handling.