Virtual University of Pakistan In the name of Allah

Virtual University of Pakistan 2 Distributed Database Management Systems Lecture - 01

Virtual University of Pakistan 3 1- Distributed Database Systems (2 nd Edition) by T.M., Ozsu, P. Valdusiez 2- Distributed Database Systems. By D. Bell, J. Grimson, Addison- Wesley, 1992 References

Virtual University of Pakistan 4 References 3- Distributed Systems: Concepts and Design, 4 th Edition, by G. Coulouris, J. Dollimore, T. Kindberg, Addison- Wesley Prerequisites: Database Management Systems, Computer Networks

Virtual University of Pakistan 5 Course of Course  Introduction to database and Distributed Systems in general  Architectures and Design Issues of DDBS  Technological Treatment  Theoretical Aspects of the topic

Virtual University of Pakistan 6 Little bit of History  Traditional File Processing System: the very first form of business data processing  Each program contains data description that it manipulates  Redundancy of data  Problems in maintenance

Virtual University of Pakistan 7 Program and Data Interdependence Registration Applications Registration Data Files Registration Examination Applications Examination Data Files Examination Library Applications Library Data Files Library

Virtual University of Pakistan 8 LibraryExamRegistration Reg_Number Name Father NameAddressFather Name Books IssuedClassPhone FineSemesterAddress GradeClass File Processing Systems Duplication of Data Vulnerable to Inconsistency

Virtual University of Pakistan 9 History continues Database Approach: (Also called centralized database) Database is a shared collection of logically related data

Virtual University of Pakistan 10 Database Data Description Data Manipulation …. PROGRAM 1 PROGRAM 2 PROGRAM 3 Database Approach Takes care of all major drawbacks of File System Environment plus more

Virtual University of Pakistan 11 Distributed Computing System A number of autonomous processing elements that are connected through a computer network and that cooperate in performing their assigned tasks

Virtual University of Pakistan 12 Distributed Computing Systems  Distributed System Software enables computers to coordinate and share  The thing being distributed? –Processing logic –Functions –Data –Control; All are relevant and important here

Virtual University of Pakistan 13 Classifications of DCS  Degree of Coupling –How closely systems are connected –May be the measured as ratio of messages interchanged to the local processing –Could be Weak (over the network) or Strong (if components are shared)

Virtual University of Pakistan 14 Classifications of DCS  Interconnection structure –Could be point to point or a common interconnection channel  Interdependence of Components  Synchronization  Factors are not totally independent

Virtual University of Pakistan 15 Why DCS?  Suits some of the Organizational Structures; more reliable and responsive  Nature of some applications  Technological Push

Virtual University of Pakistan 16 DCS’s Alerts  Information Islands and Lack of Standards  Difficulties in Large Application Design  Too Many Options Available