2. Database Architectures and the Web Session 5
Course Name : Database System
Year : 2012
Database Architectures and the Web Session 5

3. Database Architectures and the Web
Chapter 3
Database Architectures
and the Web
Pearson Education © 2009

4. Chapter 3 - Objectives
The meaning of the client–server architecture and the advantages of this type of architecture for a DBMS
The difference between two-tier, three-tier and n-tier client–server architectures
The function of an application server
The meaning of middleware and the different types of middleware that exist
The function and uses of Transaction Processing (TP) Monitors
Pearson Education © 2009

5. Chapter 3 - Objectives
The purpose of a Web service and the technological standards used
The meaning of service-oriented architecture (SOA)
The difference between distributed DBMSs, and distributed processing
The architecture of a data warehouse
The software components of a DBMS
About Oracle’s logical and physical structure

6. Multi-user DBMS Architectures
Teleprocessing
Traditional architecture for multi-user systems
One computer with a single central processing unit (CPU) and a number of terminals
Put a huge burden on the central computer
Downsizing
Replacing expensive mainframe computers with more cost-effective networks of personal computers

7. Multi-user DBMS Architectures
File-server architecture
Processing is distributed about the network
Three main disadvantages
Large amount of network traffic
Full copy of DBMS required on each workstation
Concurrency, recovery, and integrity control are complex
Multiple DBMSs can access the same files

8. File-Server Architecture

9. Multi-user DBMS Architectures
Traditional two-tier client–server architecture
Client process requires some resource
Server provides the resource
Basic separation of four main components of business application
Typical interaction between client and server

10. Traditional Two-Tier Client-Server
Client (tier 1) manages user interface and runs applications.
Server (tier 2) holds database and DBMS.
Advantages include:
wider access to existing databases;
increased performance;
possible reduction in hardware costs;
reduction in communication costs;
increased consistency.

11. Traditional Two-Tier Client-Server

12. Traditional Two-Tier Client-Server

13. Multi-user DBMS Architectures
Three-tier client–server architecture
User interface layer
Business logic and data processing layer
DBMS
Many advantages over traditional two-tier or single-tier designs

14. Three-Tier Client-Server
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.
By 1995, three layers proposed, each potentially running on a different platform.

15. Three-Tier Client-Server
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.

16. Three-Tier Client-Server

17. Multi-user DBMS Architectures
N-tier architectures
Three-tier architecture can be expanded to n tiers
Application servers
Hosts an application programming interface (API) to expose business logic and business processes for use by other applications

18. Summary of client–server functions

19. Multi-user DBMS Architectures
Middleware
Software that mediates with other software
Communication among disparate applications
Six main types
Asynchronous Remote Procedure Call (RPC)
Synchronous RPC
Publish/Subscribe
Message-Oriented middleware (MOM)
Object-request broker (ORB)
SQL-oriented data access

20. Multi-user DBMS Architectures
Transaction processing monitor
Controls data transfer between clients/servers
Provides a consistent environment, particularly for online transaction processing (OLTP)
Significant advantages
Transaction routing
Managing distributed transactions
Load balancing
Funneling
Increased reliability

21. Transaction Processing Monitors
Program that controls data transfer between clients and servers in order to provide a consistent environment, particularly for Online Transaction Processing (OLTP).

22. Multi-user DBMS Architectures
Transaction processing monitor

23. Web Services and Service-Oriented Architectures
Software system that supports interoperable machine-to-machine interaction over a network
No user interface
Examples of Web services
Uses widely accepted technologies and standards

24. Relationship between WSDL, UDDI, and SOAP

25. Web Services and Service-Oriented Architectures
Service-Oriented Architectures (SOA)
Architecture for building applications that implement business processes as sets of services
Published at a granularity relevant to the service consumer
Loosely coupled and autonomous services
Web services designed for SOA different from other Web services

26. Traditional vs. SOA Architecture

27. Distributed DBMSs Distributed database
Logically interrelated collection of shared data physically distributed over a computer network
Distributed DBMS
Software system that permits the management of the distributed database
Makes the distribution transparent to users

28. Distributed DBMSs Characteristics of DDBMS
Collection of logically related shared data
Data split into fragments
Fragments may be replicated
Fragments/replicas are allocated to sites
Sites are linked by a communications network
Data at each site is controlled by DBMS
DMBS handles local apps autonomously
Each DBMS in one or more global app

29. Distributed DBMSs Distributed processing
Centralized database that can be accessed over a computer network
System consists of data that is physically distributed across a number of sites in the network

30. Data Warehousing Data warehouse
Consolidated/integrated view of corporate data
Drawn from disparate operational data sources
Range of end-user access tools capable of supporting simple to highly complex queries to support decision making
Subject-oriented, integrated, time-variant, and nonvolatile

31. Typical Architecture of a Data Warehouse

32. Oracle Architecture Oracle’s logical database structure Tablespaces
Schemas
Data blocks
Extents/segments

33. Relationship between an Oracle Database, Tablespaces, and Datafiles

34. Oracle Architecture Oracle’s physical database structure Datafiles
Redo log files
Control files
The Oracle instance
Oracle processes and shared memory required to access information in the database