Database System Architectures Centralized vs ClientServer Architectures 1
Database System Architectures Centralized vs. Client-Server Architectures 1
Centralized m Mainframe / Centralized DBMS ® Processing ® User application programs ® User interface programs ® DBMS functionality m Dumb Terminals ® Display capabilities only ° 2
Client-Server m Decline of Hardware Prices m Dumb Terminals replaced with Personal Computers m Gradual Use of Processing Power on Client-Side m Two-Tier Architectures ® Servers with specialized functionality ® Clients provide user application programs and interface programs ° 3
Client-Server (two-tier) ° 4
Client-Server (two-tier) m Client side presented two problems preventing true scalability: ® ‘Fat’ client, requiring considerable resources on client’s computer to run effectively. ® Significant client side administration overhead. m By 1995, three layers proposed, each potentially running on a different platform. ° 5
Client-Server (three-tier) ° 6
Client-Server (three-tier) m Advantages: ® ‘Thin’ client, requiring less expensive hardware. ® Application maintenance centralized. ® Easier to modify or replace one tier without affecting others. ® Separating business logic from database functions makes it easier to implement load balancing. ® Maps quite naturally to Web environment. ° 7
Client Server Architecture ° 8
Thick client architecture ° 9
Thin ° client architecture 10
Application server architecture ° 11
Transactional application server architecture ° 12
The client-server architecture ° 13
(Totally) Distributed database systems ° 14
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