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Virtual University of Pakistan
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Distributed DatabaseDistributed DatabaseManagement SystemsManagement Systems
Lecture - 01
Virtual University of Pakistan
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1-Distributed Database Systems (2nd Edition) by T.M., Ozsu, P. Valdusiez
2- Distributed Database Systems. By D. Bell, J. Grimson, Addison-
Wesley, 1992
References
Virtual University of Pakistan
References
3- Distributed Systems: Concepts and Design, 4th Edition, by G. Coulouris, J. Dollimore, T. Kindberg, Addison-Wesley
Prerequisites: Database Management Systems, Computer Networks
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Course of Course
Introduction to database and Distributed Systems in general
Architectures and Design Issues of DDBS
Technological TreatmentTheoretical Aspects of the
topic
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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
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Program and Data Interdependence
RegistrationApplications
RegistrationDataFiles
RegistrationExaminationApplications
ExaminationDataFiles
Examination
LibraryApplications
LibraryDataFiles
Library
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Library Exam Registration
Reg_Number Reg_Number Reg_Number
Name Name Name
Father Name Address Father Name
Books Issued Class Phone
Fine Semester Address
Grade Class
File Processing Systems
Duplication of DataVulnerable to Inconsistency
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History continues
Database Approach: (Also called centralized database) Database is a shared collection of logically related data
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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
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Distributed Computing SystemA number of autonomous processing elements that are connected through a computer network and that cooperate in performing their assigned tasks
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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
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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)
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Classifications of DCS Interconnection structure
Could be point to point or a common interconnection channel
Interdependence of Components Synchronization Factors are not totally independent
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Why DCS?
Suits some of the Organizational Structures; more reliable and responsive
Nature of some applications Technological Push
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DCS’s Alerts
Information Islands and Lack of Standards Difficulties in Large Application Design Too Many Options Available
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