1. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Database Architecture Overview Client-Server and Distributed Architectures

2. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Agenda Traditional Client-Server Architecture 3-Tier Client-Server and the WWW Distributed Database Architecture Changes since the 1997 Kramer paper

3. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Client-Server Architecture

4. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Spreading the Server Responsibilities

5. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Benefits of n-tier Architectures Allows for cleaner separation of –Presentation (user interface) –Business logic –Database server But where are the lines to be drawn?

6. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Implementations on the WWW Web browser as client –HTML, JavaScript for lightweight –Java Applets for heavyweight Web server as application server –Dynamic content from CGI, Java servlets, JSP, ASP Database engine in the background –Oracle, MySQL, SQL Server

7. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Why Distributed Database Systems? Transparency Reliability and Availability Performance Expandability

8. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Transparency Distribution or network transparency –location –naming Replication transparency Fragmentation transparency –horizontal –vertical

9. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Reliability and Availability Reliability is the probability that a system will be running at some particular time. Availability is the probability that a system will be running and usable over a time interval.

10. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Performance Remote data that feels local

11. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Expandability Easier to grow something that is already spread around.

12. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Horizontal Fragmentation Derived Horizontal Fragmentation –Split whole relations

13. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Vertical Fragmentation Splitting the attributes between fragments, duplicating the primary key to allow full reconstruction of the tuple.

14. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Additional DDBMS Issues Keeping track of where data is Distributed query processing Distributed transaction management Management of data replication New problems for recovery Security Distributed directory management

15. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Types of Distributed Database Systems Homogeneous Heterogeneous Federated databases Multi-database

16. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Since 1997 Java to the backend server CORBA alternatives Applets replaced by server-side dynamic processing CGI no longer in favor

17. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Diagram

18. March 24, 2004Craig E. Ward, CMSI 698 Advanced Topics in Database Systems Questions and Discussion