1. Distributed Database Management Systems
Lecture 09

2. In the previous lecture
Derived Relational Algebra Ops…..
Relational Calculus
Computer Networks

3. In this Lecture
Networks continued
DDBMS Architecture

4. Scale

5. Local Area Network
Metropolitan Area Network
Wide Area Network

6. WANs Used Inter-City, country or even continental
Gives low bandwidth, high latency

7. Can be Broadcast and Point to Point
In Point to Point
Circuit Switching
Packet Switching

8. Circuit Switching Dedicated link b/w Sender Receiver
Maintained during conversation

9. Packet Switching
Message into Packets
May take different routes
Need to be sorted

10. Advantages of Packet Switching
Better Link Utilization
Bursty Nature of communication
Parallel transmission

11. LANs Small geographical area (usu. 2 km) High bandwidth Low latency
Technology
– Mainly Ethernet, now 100/1000Mbps

12. MANs
Between LAN and WAN
Cover city or portion
Larger LANs

13. Protocol Standards

14. Set of rules and formats for exchanging data, arranged into layers called protocol suite/ stack.

15. WAN faces max heterogeneity
Needs protocols
ISO/OSI

16. ISO/OSI Architecture
Network built in seven layers
Interfaces for passing information b/w layers

17. Protocols between corresponding layers at different sites
Lower three layers form Comm. subnet

19. TCP/IP Architecture
Another popular Architecture
Five layers
IEEE Committee 802

20. Distributed DBMS Architecture

21. Architecture of a systems defines its structure

22. Sheth, A. P., Larson, J. A., ‘
Federated Database Systems for Managing Distributed Heterogeneous, and Autonomous Databases’, ACM Computing Surveys, 22, No. 3, p( ), Sep., 90

23. Three major (idealized) architectures of DDBMS discussed
Peer to peer
Client/Server
Multidatabase

24. DBMS Standardization A conceptual framework to divide standardization
work into manageable
pieces

25. Component-based
Function-based
Data-based

26. Practically Every aspect has to be considered
These Classification schemes are Orthogonal
A committee for the task established in 1972 by ANSI under SPARC
Published standard in 1977

27. Reference Model External Conceptual Internal View Users
Internal Schema
Conceptual Schema
External Schema
Users